COMMENTARY ON THE MISTLETOES OF PANAMA'
JOB KUIJLr
ABSTRACT
An updated listing is provided for Panamanian genera and species of Loranthaceae
(Cladocolea, Gaiadendron, Oryctanthus, Phthirusa, Psittacanthus, Struthanthus, and possibly
Ixocactus), Viscaceae (Dendrophthora, Phoradendron), and Eremolepidaceae (Antidaphne).
Aside from certain nomenclatural changes, new records from Panama are: Clado-
colea oligantha (Standley & Steyermark) Kuijt, possibly Ixocactus hutchisonii Kuijt, Phora-
dendron annulatum Oliver, P. crassifolium (Pohl) Eichler, P. dichotomum (Bertero) Krug
& Urban, P. dipterum Eichler, P. quadrangulare (H.B.K.) Krug & Urban, P. robustissimum
Eichler, Psittacanthus nodosus (Desr.) G. Don, Struthanthus quercicola (Cham. & Schlecht.)
Blume, and S. aff. dichotrianthus Eichler. In addition, the following new species are described:
Dendrophthora panamensis Kuijt, Psittacanthus hamulifer Kuijt, and P. pusillus Kiijt. Six
further species are recognized but remain unnamed because of difficulties inherent in Phora-
dendron, raising the total numnber of Panamanian mistletoes to at least 45 species.
In the years since Rizzini's (1960) treatment of the mistletoes of Panama
appeared, various new points of view have arisen with regard to some of his
interpretations, and numerous new relevant facts have emerged. The following
is offered as a series of emendations.
Perhaps the most important broader change which has occurred in the in-
tervening years is the acceptance of two or even three separate mistletoe families
(Barlow, 1964; Kuijt, 1968). Ail three of these families are represented in
Panama, Eremolepidaceae (Antidaphne), Viscaceae (Dendrophthora, Phora-
dendron), and Loranthaceae, s.s. (Cladocolea, Gaiadendron, Oryctanthus,
Phthirusa, Psittacanthus, Struthanthus (incl. "Phrygilanthus" panamensis) and
possibly Ixocactus. My present comments, however, are organized in an alpha-
betical fashion. In all cases, this commentary applies to a Panamanian context, its
usefulness to adjacent geographic areas being untested. For species merely
listcd below, the reader is referred to the critical literature cited under each
genus.
KEY TO THE GENERA OF PANAMANIAN MISTLETOES
a. Phyllotaxy alternate throughout.
b. Flowers with conspicuous, aborted organs of the opposite sex; spikes lacking
distal leafy organs; petals conspicuous, 4; style at least 4 mm long .-- 2. Cladocolea
bb. Flowers lacking aborted organs; pistillate spikes normally with small, distal
leaves which may expand into full size after flowering; petals 2(3), lacking
in stalninate flowers, less than 0.5 mni in the pistillate flowers; style less than
1 mm long - --- - ... - .......... .......1. Antidaphne
aa. Phyllotaxy decussate or whorled.
c. Flowers single (not in diads, triads, or longitudinal series), individually in axil-
lary positions on the main stem, on spikes, or on racemes.
1Acknowledgements are due to the National Research Council of Canada for financial
support; to Dr. Karel U. Kramer for the Latin diagnoses; and to curators of several herbaria for
assistance rendered.
2 Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta,
Canada T1K 3M4.
ANN. MISSOURI BOT. GARD. 65: 736-763. 1978.
0026-6493/78/0736-0763/$02.95/0


KUIJT-PANAMANIAN MISTLETOES
d. Inflorescence lacking, the flowers 1-several per leaf axil; plants squamate,
the young stems obviously compressed --- 5. Ixocactus (included tentatively only)
dd. Inflorescence a raceme or spike; plants leafy, the stems terete or slightly
compressed.
e. Inflorescence a spike, the flowers or fruits sessile, often in depressions,
always flanked by 2 minute, separate bracteoles; flowers less than 5
mm long ...---------------..---------------.. 6. Oryctanthus
ee. Inflorescence a raceme, the individual flowers pedicellate, the pedicel
supporting a bract and 2 fused bracteoles; flowers more than 8 mm
long ...- .-------- 10-5. Struthanthus panamensis (Rizz.) Barlow & Wiens
cc. Flowers sessile above bracts, usually in longitudinal series, or in diads or triads.
f. Flowers sessile in depressions above the inflorescence bracts, always lacking
individual bracteoles, and never in diads or triads; plants squamate or leafy.
g. Anthers unilocular; plants squamate or leafy; flowers in single or
multiple series above the bracts .. -- --- - 3. Dendrophthora
gg. Anthers bilocular; plants leafy; flowers always in multiple series above
the bracts --....-...-...---- -.----------------------------- 7. Phoradendron
ff. Flowers and/or triads (diads) stalked, not in depressions, the flowers al-
ways with individual bracts or bracteoles; plants leafy.
h. Plants dioecious, the flowers with aborted stamens or style.
i. Filaments thin; inflorescence a simple raceme - 10. Struthanthus
ii. Filaments stout, the upper ones with lateral depressions; inflores-
cence a panicle .......--------- 8-1. Phthirusa adunca (Meyer) Maguire
hh. Plants with the flowers hermaphroditic.
j. Flowers golden yellow, subtended by green leafy bracts; parasites
or seemingly epiphytes on tree branches, or terrestrial _ 4. Gaiadendron
jj. Flowers at least partly red or orange, not subtended by leafy bracts;
parasites on tree branches.
k. Flowers less than 4 mm long; epicortical roots from base of
plant; fruit with endosperm ...------.---
8-2. Phthirusa pyrifolia (H.B.K.) Eichler
kk. Flowers more than 10 mm long; epicortical roots lacking; fruit
without endosperm ... .. .--------....... 9. Psittacanthus
1. ANTIDAPHNE Poepp. & Endl., Nov. Gen. & Sp. Pl. 2: 70, tab. 199. 1838.
The genus and two others not occurring in Central America (Eremolepis
and Eubrachion) have been placed in a separate family, Eremolepidaceae. The
species below, the only one in Central America, ranges from Mexico and Guate-
mala into South America.
Critical literature: Rizzini, 1956; Kuijt, 1964, 1968.
1. Antidaphne viscoidea Poepp. & Endl., Nov. Gen. & Sp. Pl. 2: 70, tab. 199.
1838.
This is the only species of the genus in Panama. The following are recent
collections.
CHIRIQUi: Slopes on Cerro Horqueta, 1650 m, Croat 26950 (MO). Lava fields near
Volcan, 4600 ft, Duke 9178 (MO). 1 mi from El Volcan, Ebinger 774 (MO). 3 km NW of
Boquete, 1320 m, Nee 10627 (MO). Roadsides S of Boquete, 1050-1100 m, Nee 10647
(MO). 1 km NE of El Hato del Volcan, 1440 m, Nee 14128 (MO). S side of El Hato del
Volcan, 1390 m, Nee 14147 (MO). DARI�N: Summit of Pico Tacarcuna, 1850 m, Gentry
et al. 16904 (MO). PANAMA: Road from El Llano to Carti-Tupile, 12 km above Pan-Am.
Highway, 200-250 m, Croat 22906 (MO).
2. CLADOCOLEA Van Tieghem, Bull. Soc. Bot. France 42: 166. 1895.
1978]
737


ANNALS OF THE MISSOURI BOTANICAL GARDEN
Erect or scandent parasitic shrubs, glabrous or short-pubescent; lateral
branches (including inflorescences) often emerging in a pseudo-endogenous
fashion; epicortical roots on stems or at the base of the plant or absent. Leaves
decussate, alternate, or irregularly arranged, simple, with pinnate venation, some-
times reduced to scales. Plants dioecious or with flowers hermaphroditic; in the
former case aborted organs of the opposite sex usually present. Inflorescence
normally a determinate spike, capitulum, dichasium, or raceme, in some species
having undergone loss of the terminal flower or having been reduced to a single
flower with 1 pair of bracts; lateral flowers ebracteolate, single in the axils of
squamate (sometimes caducous) or foliaceous bracts. Flowers pale green to
pale yellow, sessile or pedicellate, 4-, 5-, or 6-partite; stamens fused with the
perianth members, dimorphic or monomorphic, with 4 thecae; pollen rounded
triangular, sometimes with a triradiate groove and included triangular prom-
inence, otherwise smooth; style often contorted or geniculate, especially in the
upper portion. Fruit a 1-seeded berry with endosperm; embryo dicotyledonous,
elongate, or globular, the haustorial disc weakly developed.
This generic name has lain dormant since 1895 and has recently been revived
to accommodate various species assigned to Struthanthus, Phthirusa, and Oryc-
tanthus, plus a number of previously undescribed species, making a total of 23
species. Most of these species are found in Mexico but a few are South American.
Cladocolea oligantha, however, is Guatemalan except for the remarkable dis-
junct population represented by the two collections below. Most members of the
genus are characterized by a determinate spike of sessile, ebracteolate flowers.
In the case of the Panamanian species the spike is reduced to three flowers, but
the spikes occur in two slightly different forms, depending upon the age of the
branch supporting them. The type of C. oligantha is from Guatemala.
Critical literature: Kuijt, 1975.
1. Cladocolea oligantha (Standley & Steyermark) Kuijt, J. Arnold Arbor.
56: 317. 1975.
Struthanthus oliganthus Standley & Steyermark, Publ. Field Mus. Nat. Hist., Bot. Ser. 23: 154.
1944.
Plants dioecious, sparsely branched, completely glabrous, with sympodial
growth; stems rather stout and straight, terete, first light colored, later dark
brown and often with a sprinkling of rather large, transverse lenticels; 1-year-old
wood (bearing secondary inflorescences) with shrunken bark, as if cortex very
fleshy; no basal or stem roots seen. Leaves alternate, 20-30(-45) mm long, 8-10
(-16) mm wide, lanceolate to oblanceolate, acute to rounded at the apex,
long-tapering at the base into a petiole 2-4 mm long and 0.5-2 mm thick; mid-
vein running into the apex, other veins often obscure, pinnate except for 2 large,
basal lateral veins running halfway down the length of the blade. Inflorescences
of 2 types: (1) primary, on current year's growth, mostly single (rarely with
a superposed inflorescence), axillary, simple dichasia on peduncles 4-5(-10)
mm long and 1 mm thick, the bracts of 2 lateral flowers caducous, the 3 flowers
738
[VOL. 65


KUIJT-PANAMANIAN MISTLETOES
in one plane; and (2) secondary, developing on year-old growth, bearing 1 or
2 small but normal foliage leaves at the very base, deceptively like primary
leaves, the flowers 4-6, one of which is terminal, the others crowded nearby,
spirally arranged. Flowers said to be reddish, ca. 5 mm long and 2 mm wide
when in (clavate) bud, tetramerous; anthers 1.5 mm long, inserted in the middle
of the petals, with projecting connective and 4 pollen sacs; stamens and petals
monomorphic; style straight or nearly so, at least 4 mm long, the stigma in-
conspicuous. Fruit red, becoming black, 7 mm long, 5 mm wide, ovoid, smooth;
embryo dicotyledonous, nearly 4 mm long, clavate.
PANAMA: Vicinity of Las Lajas bridge, Panama National Highway, Bartlett & Lasser
16645 (MO). Near beach at Nueva Gorgina, on Bursera tomentosa, Duke 4504 (GH, MO,
US).
3. DENDROPHTHORA Eichler, Fl. Bras. 5(2): 102. 1868.
The genus is distinguished from Phoradendron by its unilocular anthers
(Phoradendron has bilocular ones). This distinction is inconvenient but ap-
parently consistent. It should be mentioned that the statement "cataphylls
poorly developed" in the earlier Panamanian treatment is unreliable by way
of a generic feature, as many Dendrophthora species have cataphylls (for ex-
ample, all Panamanian species but D. squamigera). A fifth species, D. ambigua
Kuijt (Kuijt, 1961b) may be expected in Panama, as it occurs both in Costa
Rica and in Colombia-Ecuador. As in the case of others, it may easily be
confused with Phoradendron spp.; however, it has a uniquely variable inflores-
cence type (Kuijt, 1961b, 1964).
Critical literature: Kuijt, 1961b, 1963b, 1964.
a. Plants leafy; flowers in 3 series above each fertile bract (except sometimes the small,
terminal intemodes); inflorescence with 2-3 fertile internodes.
b. Plants monoecious; leaves broadly obovate; flowers more than 6 per bract -----
----- ------. -----.............. ........ .. - .. 1. D. costaricensis Urban
bb. Plants dioecious; leaves lanceolate to rhombic or spatulate; flowers fewer than
6 per bract in female plants only.
c. Lateral branches usually with 2 pairs of widely spaced basal cataphylls
at least 7 mm from each other or above the axil; young stems compressed,
with ridges -- ----- --------.................... 4. D. sp.
ce. Lateral branches with 1 (rarely 2) pairs of basal cataphylls less than 5
mm from each other or above the axil; young stems more or less terete,
lacking ridges ....-------........--.....------.---.-------. 2. D. panamensis Kuijt
aa. Plants squamate, olive green to brown; flowers in a single series above each fertile
bract; inflorescence usually with a single fertile intemode -----------....... .........--...
.--------------....-----................ . ................._. 3. D. squamigera (Benth.) Kuntze
1. Dendrophthora costaricensis Urban, Ber. Deutsch. Bot. Ges. 14: 285. 1896.
Phoradendron allenii Trelease, Ann. Missouri Bot. Gard. 27: 307. 1940.
P. crispum Trelease, Gen. Phor. 17. 1916.
2. Dendrophthora panamensis Kuijt, sp. nov.-FIG. 1.
Frutex glaber, ramosissimus, dioecus; intemodia novella superne pauce applanata, inferne
quadrangularia; rami laterales cataphyllis basalibus uni-(raro bi-)jugis, 2 ad 3 mm supra axillam
1978]
739


740
ANNALS OF THE MISSOURI BOTANICAL GARDEN
2L
FI;URES 1-2.-1. Dendrophthora panaiuensis Kuijt, the (pistillate) type at left (Liesner
1305), a stamninate spike at right (Mori, Kallunki & Gentry 4703).-2. Dendrophthora sp. No.
4 (Croat 26949).
positis. Folia rhomboidea ad lanceolata, usque ad 4 X 1.5 cm. Spica pistillata 1-1.5 cm
longa, internodio sterili singulo, fertilibus tribus, floribus ternis pro bractea. Fructus baccatus,
paulum compressus, cire. 2 mm diam. Spica staminata similis sed floribus pro bractea fertili
usque ad 14.
Glabrous, much branched (percurrent) and brownish green mistletoes, the
young internodes somewhat flattened above and slightly quadrangular below,
soon becoming terete; lateral branches with one pair of inconspicuous, very basal
cataphylls, sometimes followed by a second several mm higher. Leaves thin,
to 4 cm long and 1.5 cm wide, thin, rhombic to lanceolate, with clearly defined
[VOL. 65


KUIJT-PANAMANIAN MISTLETOES
callused margin, the apex acute to rounded, the base cuneately tapered into a peti-
ole about 3 mm long. Dioecious. Pistillate spike 1-1.5 cm long, slender, with 1
sterile internode and 3 fertile ones, the latter with ca. 3 flowers per bract (1 flower
per bract on the terminal internode) on the distal portion of the internode. Fruit
a compressed berry 2 mm in diameter. Staminate spike of similar size and com-
position, but with up to 14 orange yellow flowers per fertile bract in lb arrange-
ment (cf. Kuijt, 1963b), and sometimes a second sterile internode; anther bean
shaped, unilocular, less than 0.5 mm long.
This is an inconspicuous species easily mistaken for a Phoradendron, but
with clearly unilocular (though extremely small) anthers. Dendrophthora pan-
amensis is a member of the D. costaricensis group of subgenus Paradendroph-
thora, as also indicated by the flattened berries which occur only in that subgenus
(Kuijt, 1961b, 1964).
TYPE: PANAMA. SAN BLAS: Primary forest along newly cut road from El
Llano to Carti-Tupile, continental divide to 1 mi from divide, 300-500 m,
Liesner 1305 (MO, holotype; LEA, isotype).
Other material examined: PANAMA: El Llano-Carti Road, 12.7 km from Inter-American
Highway, wet forest, 350 m, Mori, Kallunki & Gentry 4703 (MO, LEA).
3. Dendrophthora squamigera (Benth.) Kuntze, Rev. Gen. 2: 505. 1891.
D. biserrula Eichler, FI. Bras. 5(2): 104. 1868.
4. Dendrophthora sp.-FIG. 2.
Much branched, stiffly erect shrub with internodes to 4 cm long, compressed,
with 2 sharp ridges, becoming terete in age; percurrent branches without cata-
phylls; lateral branches with 2 (rarely 1) pairs of cataphylls widely spaced, the
lowest 7-20 mm above axil, the second pair somewhat more above the first pair.
Leaves narrowly spatulate, to 6 cm long and 1.5 cm wide, with long-tapering bases
and obtuse apices. Spikes 1 per axil, or 2 flanking each lateral branch, to 2.5 cm
long with 3-4 fertile internodes, basal cataphylls lacking (rarely with 1 pair),
3-4 flowers per bract in 3 series in the middle of fertile internodes, the terminal
internode very blunt.
The absence of anthers deprives us of proof that this indeed is a Dendroph-
thora rather than a Phoradendron; the plant is pistillate with nearly mature
spikes. However, its general appearance, especially the widely spaced, usually
double set of basal cataphylls, suggests a Dendrophthora. Even if it is, it may
easily already have received a name under Phoradendron, and it seems better
simply to draw attention to it.
CHIRIQUI: In and along wooded slopes on Cerro Horqueta, 1650 m, Croat 26949 (MO).
4. GAIADENDRON G. Don, Gen. Syst. 3: 431. 1834.
1. Gaiadendron punctatum (Ruiz & Pav6n) G. Don., Gen. Syst. 3: 431. 1834.
G. poasense Donnell Smith, Bot. Gaz. (Crawfordsville) 56: 61. 1913.
1978]
741


ANNALS OF THE MISSOURI BOTANICAL GARDEN
Rizzini's suggestion that Gaiadendron must probably be returned to Phry-
gilanthus sensu Eichler has not been supported by subsequent work. Barlow
& Weins (1973) have shown Phrygilanthus to be a very heterogenous group
which cannot be retained as such. Gaiadendron according to Barlow & Wiens
is best treated as a monotypic genus with a single polymorphic species, G.
punctatum. Whether or not this is a defensible view, ail Central American ma-
terial is clearly referable to G. punctatum. It is of some interest that in this
area the species occurs both at the diploid and tetraploid levels (Barlow &
Wiens, 1971). The genus has hermaphroditic flowers, my previous description
of G. punctatum as a monoecious species (Kuijt, 1964) being in error.
Critical literature: Barlow & Wiens, 1971, 1973; Kuijt, 1963a, 1964.
5. IxOCACTUS Rizz., Arch. Jard. Bot. Rio de Janeiro 12: 118. 1952.
1. Ixocactus hutchisonii Kuijt, Brittonia 19: 62. 1967.
A small, olive green, squamate shrub with decussating, minute scale leaves, the
internodes to 7 cm long, much compressed, oblong to somewhat rhombic; lateral
branches (or flowers) at most 5 per axil. Flowers perfect, 2 mm long and 1 mm
thick in bud; petals 4 (3), broadly oval, each with a sessile anther provided
with 2 minute pollen sacs dehiscing longitudinally, the pollen sacs with no more
than 30 grains each, the anthers (sometimes pollen sacs of a single anther) often
at different heights, at least in tetramerous flowers, the pollen commonly quad-
ricolpate with a dense covering of stout spines and four conspicuous, longitudinal
colps; style bluntly conical, persistent, the stigma capitate. Fruit an oval berry,
at least 3.5 mm long and 2 mm thick.
This striking monotypic genus has so far been known only from two collec-
tions from Venezuela and Colombia. In the Stockholm Herbarium, however, there
exists an early collection of I. hutchisonii apparently from Panama. The ac-
companying data are, unfortunately, very scanty: N. J. Andersson, Panama,
April 1852. There are two separate sheets. Dr. Benkt Sparre, Curator of the
Regnellian Herbarium, confirms that Andersson was indeed in Panama in April,
1852, but that Andersson was a rather careless collector. The possibility that
material from the previous collecting area (Isla Puna outside Guayaquil in
Ecuador) was invadvertently labelled "Panama" can be neither excluded nor
confirmed. It is also known that Andersson visited the Pearl Islands (Panama) at
about this time, but his diary provides no further information on the matter. I
feel there is no alternative but to add Ixocactus to the Flora of Panama, even
though on a tentative basis only. The brief description is taken from Kuijt
(1967) where illustrations may also be found.
6. ORYCTANTHUS Eichler, Fl. Bras. 5: 87. 1868.
This genus has recently been monographed, resulting in a number of nomen-
clatural and taxonomic changes from both Rizzini's (1960) treatment of Panama
and mine (Kuijt, 1964) for Costa Rica, as indicated below.
742
[VOL. 65


KUIJT-PANAMANIAN MISTLETOES
Critical literature: Kuijt, 1961a, 1976a.
a. Flowers and fruits perpendicular to the inflorescence axis.
b. Stems terete even when young _--.. . 3. O. occidentalis (L.) Eichler
bb. Stems strongly compressed or angular when young ------------------........... ----
---- - . .--- ..-- ... ..... ... - .... 2. O. cordifolius (Presl) Urban
aa. Flowers and fruits inclined forward.
c. Plants small; leaves petiolate, rather thin, the midrib running into the leaf
apex; stems angular and with furfuraceous lines when young; spikes slender,
always with a distinct peduncle, never in terminal compound groups --_----
-------------.-......-...... . ..._ .._...... . 4. O. spicatus (Jacq.) Eichler'
ce. Plants coarse; leaves short-petiolate or clasping, leathery, the midrib (if visible)
not running into the apex; stems terete, with a general (not lined) furfuraceous
covering when young; spikes stout, with a thick peduncle or nearly sessile,
axillary, in some also in terminal compound groups ----------------------------
.....------... ---_____-------........._ . ..-. -....... 1. O. alveolatus (H.B.K.) Kuijt
1. Oryctanthus alveolatus4 (H.B.K.) Kuijt, Bot. Jahrb. Syst. 95: 504. 1976.
Loranthus alveolatus H.B.K., Nov. Gen. Sp. Pl., Quarto text, 3: 444. 1820.
Oryctanthus amplexicaulis (H.B.K.) Eichler, FI. Bras. 5(2): 88. 1868.
O. botryostachys Eichler, Fl. Bras. 5(2): 89. 1868.
This is a widespread and taxonomically difficult complex which in past works
has been referred to as O. amplexicaulis and O. botryostachys in Central America
and parts of South America. It may well be that two such variants (one
amplexicaul and with terminal compound inflorescences, the other petioled and
with only axillary spikes) warrant some subspecific status in the area, but at
present such a delimitation is impossible in South America. It should be noted
that Rizzini (1960) used the name O. spicatus with reference to the second
variant, known elsewhere as O. botryostachys.
2. Oryctanthus cordifolius (Presl) Urban, Bot. Jahrb. Syst. 24: 30. 1898.
This is an easily recognized species by its combination of large, clasping leaves
and sharp-angled stems.
3. Oryctanthus occidentalis (L.) Eichler, Fl. Bras. 5(2): 89. 1868.
Frequently confused with some plants of O. alveolatus, and more rarely O.
cordifolius, O. occidentalis nevertheless does not intergrade with these spe-
cies, and can always be identified when using the keys consistently. The species
has a parallel geographie range and taxonomic complexity as compared to O.
alveolatus, but also occurs on Jamaica.
4. Oryctanthus spicatus (Jacq.) Eichler, Fl. Bras. 5(2): 89. 1868.
Notwithstanding inclusion of this name in Rizzini's (1960) treatment (see
above under O. alveolatus), authentic O. spicatus material does not seem to
have been collected yet from Panama. This is surprising since its total geo-
graphic range stretches from Guatemala to Peru, the species being especially
a See note under O. spicatus.
' For further synonymy, see Kuijt (1976a).
1978]
743


ANNALS OF THE MISSOURI BOTANICAL GARDEN
common in both Costa Rica and Colombia. As it seems reasonable to expect this
inconspicuous mistletoe at least in the mountainous northerly portions of Pan-
ama, it is here tentatively included.
7. PHORADENDRON Nuttall, J. Acad. Nat. Sci. Philadelphia, ser. 2, 1: 185. 1847.
I am disappointed to find that I can no more construct a key to Panamanian
Phoradendron than I can identify several unnamed species-and for very sim-
ilar reasons. The distinctions between P. quadrangulare and the almost exclu-
sively Caribbean P. trinervium, for example, need first to be clarified, and I
am presently not in a position to do this.
Critical literature: Kuijt, 1959; Trelease, 1916, 1940.
1. Phoradendron acinacifolium Eichler, Fl. Bras. 5(2): 117. 1868.
Phoradendron robaloense Woods. ex Rizz., Ann. Missouri Bot. Gard. 47: 282. 1960.
Although the two collections below correspond to Costa Rican plants (Kuijt,
1964), the specific epithet here used belongs to Brazilian material, and is possibly
inappropriate.
CHiR1QUi: Bajo Mona, Robalo Trail, 1500-2100 m, Allen 4838 (MO, holotype of P.
robaloense). COLON: East ridge, Duke 15274 (MO).
2. Phoradendron angustifolium (H.B.K.) Nuttall, J. Acad. Nat. Sci. Phila-
delphia, ser. 2, 1: 185. 1847.
Viscum stenophyllum Spreng., Syst. Veg. 1: 487. 1825, non Phoradendron stenophyllum
Trelease, Gen. Phor. 81. 1916.
Loranthus angustifolius H.B.K., Nov. Gen. Sp. Pl. 3: 442. 1820.
Viscum angustifolium (H.B.K.) DC., Prodr. 4: 281. 1830.
V. ensifolium Pohl in DC., Prodr. 4: 281. 1830.
Phoradendron ensifolium (Pohl) Nuttall, J. Acad. Nat. Sci. Philadelphia, ser. 2, 1: 185. 1847.
P. corynarthron Eichler, Fl. Bras. 5: 115. 1868.
P. cooperi Trelease, Gen. Phor. 67. 1916.
?P pringlei Trelease, Gen. Phor. 60. 1916.
P. tonduzii Trelease, Gen. Phor. 67. 1916.
P. dodgei Trelease, Publ. Field Mus. Nat. Hist., Bot. Ser. 18: 405. 1937.
P davidsoniae Standley, Publ. Field Mus. Nat. Hist., Bot Ser. 22: 17. 1940.
P. novae-helveticae Trelease, Ann. Missouri Bot. Gard. 27: 307. 1940.
As visualized here, we are concerned with a not exceptionally polymorphic
species ranging from Costa Rica into Peru, Bolivia, and Brazil. The variability in
leaf width and length, but also in flower seriation, has brought about the exces-
sive synonymy above.
3. Phoradendron annulatum Oliver, Vidensk. Meddel. Dansk Naturhist. Foren.
Kj0benhavn 1864: 176. 1865.
See comments under No. 19.
CHImQUi: Boqiete District, Volcain de Chiriqui, 10,000 ft. Davidson 996 (F).
744
[VOL. 65


KUIJT-PANAMANIAN MISTLETOES
4. Phoradendron crassifolium (Pohl) Eichler, Fl. Bras. 5(2): 125. 1868.
The species is unmistakable because of the production of spikes in the axils
of intercalary cataphylls (Kuijt, 1959), a feature not found in any other Central
American mistletoe. Superficially, the species resembles P. woodsonii and
species No. 18 where intercalary cataphylls are always sterile.
CANAL ZONE: 5 mi N of Gamboa, Lazor & Blum 5333 (DUKE, MO). CHIRIQUi: Volcan,
Croat 10425 (DUKE, MO). Cerro Hornitos, 40 km NW of Gualaca, 2238 m, Mori & Bolten
7512 (MO). COLON: Santa Rita Ridge, Foster 1720 (DUKE). DARI�N: El Real, Burch et al.
1060 (DUKE, MO). Forest near Pidiaque Peak, 800-1000 ft, Duke 8070 (MO). PANAMA:
Camino a Chepo, Correa et al. 996 (DUKE, MO). Cerro Jefe, 2100-2200 ft, Duke 15222
(MO). Cerro Azul, Dwyer 1382, 2068 (both MO). Cerro Jefe, 800-1000 m, Gentry 2888
(MO). Punta de Cerro Jefe, Gdmez-Pompa et al. 3081 (MO). 16-20 km above Pan-Am.
Highway on road from El Llano to Carti-Tupile, 400 m, Kennedy 2702 (MO). Road past
Cerro Azul 20 km from junction with road through Tocumen, Mori & Kallunki 2210 (MO).
VERAGUAS: Isla de Coiba, Dwyer 2337 (MO).
5. Phoradendron dichotomum (Bertero) Krug & Urban, Bot. Jahrb. Syst. 24:
48. 1897.
Assignment of the two specimens cited below to P. dichotomum is tentative.
They are both unusually stout as compared with Costa Rican material, the leaf
pairs of the second collection 20 cm apart, and the leaves rather leathery. The
same specimen is clearly staminate, while Costa Rican material was thought to
be monoecious (Kuijt, 1964). In ail other respects, especially the terminal spikes
which as a regular feature are not known from other Central American species,
the plants correspond to P. dichotomum. See the discussion in Kuijt (1964) of
the geographical range of this mistletoe.
PANAMA: El Llano-Carti road, 12.7 km from Inter-American Highway, on melastome,
350 m, Mori et al. 4678 (MO). VERAGUAS: 5 mi W of Santa F�, 800-1200 m, Croat 23055
(MO).
6. Phoradendron dipterum Eichler, Fl. Bras. 5(2): 109. 1868.
This is an interesting species, here reported from Panama for the first time,
thus linking South American collections with those from Costa Rica and further
north (Kuijt, 1964). Panamanian material is similar to that from Costa Rica
in having stems quadrangular rather than winged, but it differs somewhat in
that the leaves are not clasping, and the spikes are rather small.
LOS SANTOS: Pocri, Dwyer 2518 (MO).
7. Phoradendron flavens (Swartz) Griseb., Fl. Brit. W. I. 33. 1864.
P. quinquenervium Krause, Notizbl. Konigl. Bot. Gart. Berlin 5: 264. 1912.
P. supravenulosum Trelease, Gen. Phor. 154. 1916.
See the discussion under P. flavens in Kuijt (1964).
8. Phoradendron mucronatum (DC.) Krug & Urban, Bot. Jahrb. Syst. 24:
352. 1897.
745
1978]


ANNALS OF THE MISSOURI BOTANICAL GARDEN
9. Phoradendron obliquum (Presl) Eichler, FI. Bras. 5(2): 134. 1868.
Having studied the type material at Prague (Haenke s.n., from Peru), I no
longer doubt that Central American plants are conspecific with it. In particular,
the type appears to have flowers of both sexes on the same spike, rendering it
monoecious as the plants in Costa Rica (Kuijt, 1964) and Panama.
CANAL ZONE: 12 mi N of Gamboa, on Xanthoxylum belizensis Lundell, Tyson 6653 (MO).
4 km NW of Gamboa, 50 m, Nee 7540 (MO). DAR�N: Vicinity of El Real along road to air-
port, on Xanthoxylum, Croat 15443 (MO). PANAMA: Vicinity of El Llano, on Vitex, Duke
5796 (MO). Cerro Jefe, 2700-3000 ft, Tyson et al. 3282 (MO).
10. Phoradendron piperoides (H.B.K.) Trelease, Gen. Phor. 145. 1916.
11. Phoradendron quadrangulare (H.B.K.) Krug & Urban, Bot. Jahrb. Syst.
24: 35. 1897.
P. ceibanum Trelease, Gen. Phor. 110. 1916.
P. rensonii Trelease, Gen. Phor. 105. 1916.
P. venezuelense Trelease, Gen. Phor. 111. 1916.
P. paquitanum Trelease, Publ. Field Mus. Nat. Hist., Bot. Ser. 18: 405. 1937.
P. corynarthron Eichler var. seibertii Trelease, Ann. Missouri Bot. Gard. 24: 187. 1937.
P. seihertii Rizz., Ann. Missouri Bot. Gard. 47: 285. 1960.
Consistent application of the concept of P. quadrangulare as employed by
Standley & Steyermark (1946) in the Flora of Guatemala results in at least the
above synonyms from Costa Rica and Panama. Undoubtedly, more synonyms
will accrue when this difficult species can be surveyed as a whole, as indicated
in the further synonyms in Standley & Steyermark (1946) and Rizzini (1960).
Only a few representative collections from Panama are listed below; the species
may be expected at lower elevations throughout Panama.
BOCAS IDEL TORO: Hill above RR station at Milla 7.5, an Cassia reticulata, Croat & Porter
16364 (MO). CANAL ZONE: Diablo Heights, 10 m, Nee 11151 (MO). 1.5 km SE of Pedro
Miguel, 15 m, Nec 10192 (MO). Just inland from Playa Kobbe, Wilbur & Teeri 12993
(DUKE). PANAMA: Cerro Jefe, 2900 ft, Dwyer & Hayden 8080 (MO, LEA). VERAGUAS:
Road between San Francisco and Santa F�, Stern et al. 1929 (MO).
12. Phoradendron robustissimum Eichler, FI. Bras. 5(2): 122. 1868.
P. pergranulatum Trelease, Ann. Missouri Bot. Gard. 27: 308. 1940.
This species has previously been reported from Venezuela, from Costa Rica
to southern Mexico (Kuijt, 1964), and (as P. pergranulatum Trelease, based
on a single specimen) from Panama. The latter specimen is clearly dichotomous
as Costa Rican plants, but the others here cited also (or only) show percurrent
branching.
CHIIUQUi: 1; km NW of Boquete on road to El Salto, 1280 m, Nee 10655 (MO, LEA).
COCL�: El Valle, 800-1000 m, Allen 777 (ILL, type of P. pergranulatum Trelease). El Valle
de Ant6n, 1000-2000 ft, Lewis et al. 2571 (MO, LEA). LOS SANTOS: 7 mi S of Las Tablas,
D'Arcy & Crout 4204 (MO). PANAMA: 7 mi S of Campana, 3-30 m, McDaniel 8335 (DUKE).
13. Phoradendron trinervium Griseb., F1. Brit. W. I. 314. 1860.
746
[VOL. 65


KUIJT-PANAMANIAN MISTLETOES
14. Phoradendron undulatum Eichler, Fl. Bras. 5(2):122. 1868.
P. gracilispicum Trelease, Gen. Phor. 130. 1916.
Trelease (1916) mentions two further specimens from Chiriqui (Pittier 2932,
3312) which I have not seen.
CHmRQUi: Lava fields 2.2 mi E of Hato del Volcan, Luteyn 810 (DUKE, MO).
15. Phoradendron woodsonii Trelease, Ann. Missouri Bot. Gard. 27: 308. 1940.
A rather small species; stems terete, the percurrent internodes with 2-4 pairs
of sterile intercalary cataphylls. Leaves to 5.5 cm long and 2.5 cm wide, ovate
to lanceolate, the margin callused, the base tapering into a short stout petiole.
Spikes clustered at leafy nodes, ca. 5 cm long, consisting of 5 or 6 fertile and
2 or 3 sterile, short internodes. Flowers in 3 series above each bract, ca. 9 per
bract, and near the middle of the internode, the terminal internode reduced and
sharply pointed. Fruit short-ovate, ca. 2 mm thick, the petals closed.
This species is closely related to the unnamed species No. 18, but differs as
there specified. Other near relatives are P. crassifolium and P. piperoides. Pre-
viously it was known from the type collection only.
CHIRIQUi: Cerro Hornitos, 40 km NW of Gualaca, 2238 m, Mori & Bolten 7512 (MO).
3 km N of El Volcan, 5000 ft, Tyson 5727 (MO). COCL�: Between Las Margaritas and El Valle,
Woodson et al. 1302 (ILL, type). PANAMA: La Campana, Cerro Campana, Duke 10743
(MO, OS); Ebinger 343 (MO). Road from Cerro Azul to Cerro Jefe, 2300-2700 ft, Tyson
4312 (MO).
16. Phoradendron sp.-FIG. 3.
Light green plants; stems straight, terete, forking through formation of
terminal spikes; lateral stems with 3 or 4 pairs of basal cataphylls mostly crowded
at the base. Leaves to 8 cm long and 3.5 cm wide, palmate venation apparent
on both surfaces, obovate to spatulate, the apex obtuse to emarginate, the base
cuneately tapering to a short, stout petiole about 3 mm long. Dioecious; only
pistillate plants seen. Pistillate spikes terminal and axillary, with very short
sterile internodes and 3-4 fertile ones, each spike up to 2 cm long. Flowers
mostly one above each bract but sometimes 2-5 in lb (cf. Kuijt, 1963b) arrange-
ment, or with 2 flowers very nearly above each other; petals and berres orange,
ovate, at least 2 mm wide and 4 mm long when dry with closed petals, the base
sunken in a conspicuous floral cup.
This species does not seem to be included in Trelease's (1916) monograph
but may have been published subsequently. It is distinctive in its terminal
spikes and forking habit, and in the flower position which sometimes mimics
the 2a type (cf. Kuijt, 1963b) which is restricted to Dendrophthora. In the
present species the two flowers which follow the apical one above each bract
apparently are often reduced to a single one, and this one very nearly occupies a
median position (Fig. 3, lower left). Although technically it cannot be established
that the species is correctly assigned to Phoradendron (the collections are pistil-
late, and the generic distinction from Dendrophthora relies mostly on anther struc-
19781
747


ANNALS OF THE MISSOURI BOTANICAL GARDEN
3
FrGcIRE 3.-Phoradendron sp. No. 16, habit (Nee 10880) and inflorescence details (Nee
7420).
ture), it is here placed in the former genus because of its forking habit and
multiple cataphylls, neither of which feature is known from continental Dendroph-
thora.
CANAL ZONE: Summit Garden, 80 m, Nee 7420 (MO, LEA). Along Chagres River, 2
km S of Fort San Lorenzo, sea level, Nee 10880 (MO, LEA). DAmI�N: Puerto Saint Dorotea,
on beach, Dwyer 2260 (MO).
17. Phoradendron aff. racemosum (Aubl.) Krug & Urban, Bot. Jahrb. Syst.
24: 46. 1897.
Large plants, the internodes up to 7 cm long, distally compressed when
young, soon becoming terete; cataphylls on lateral branches 1 pair, rarely 2 or
3, about 5 mm above base, none on percurrent internodes. Leaves to 15 cm
748
[VOL. 65


KUIJT-PANAMANIAN MISTLETOES
long and 6 cm wide, rather thin, ovate, the venation pinnate, the midvein very
prominent below, the petiole ca. 15 mm long, gradually tapering into the base
of the blade, the apex rounded. Spikes lax or even sinuous, lacking basal cata-
phylls, the peduncle 5-7 mm long, the internodes to 3 cm long, the bracts with
ca. 15 flowers mostly in 2 series, the mature spike up to 9 cm long. Berries more
or less spherical, 4-5 mm in diameter, the perianth inflexed.
The specimen cited below is undoubtedly related to P. racemosum but may
not be conspecific with it.
True P. racemosum is known from the northerly Caribbean islands and from
the French Guyana-Venezuela area (Trelease, 1916). Our Panamanian material
differs in having compressed young stems, large berries (4-5 mm, about twice
the size of those of true P. racemosum), spikes up to 9 cm long, and the fertile
internodes longer and with more flowers, mostly in two series. Ail flowers on the
plant seem to be pistillate, while Trelease implies a monoecious condition for
P. racemosum.
cIRIQUi: Cerro Colorado, along road between San Felix and Cerro Colorado, 2.3 km
from turn-off to Escopeta, 1000 m, Croat 37069 (MO).
18. Phoradendron sp.-FIG. 4.
Rather sparsely and teretely branched plants; both percurrent and lateral
branches with 3-4 pairs of sterile cataphylls, the branch tips sometimes aborting?
Leaves rather thick, pinnately but obscurely veined except for the prominent
midrib, broadly lanceolate, the apex attenuate, the petiole 10-15 mm long, the
blade to 12 cm long and 5 cm wide. Probably monoecious. Spike ca. 45 mm long,
with several short, sterile internodes and 4-5 fertile ones. Flowers in la and lb
(cf. Kuijt, 1936b) arrangement, the apical ones on many internodes apparently
staminate, the others pistillate. Fruit ovate, 4 mm long, 3 mm wide, the petals
closed.
This species seems to be almost exactly intermediate between P. crassifolium
and P. piperoides. It shares the several intercalary cataphylls and proportions
of leaves and spikes with the former, but these cataphylls bear no spikes, and
leaf venation is not palmate as in P. crassifolium. Phoradendron piperoides, on
the other hand, has only one pair of intercalary cataphylls, is smaller in leaf,
petiole, and fruit, and its spikes bear more, but more spherical bernes. The
only other species with several sterile intercalary cataphylls is P. woodsonii. It
differs in having leaves no more than half as long as the above, and in having
correspondingly shorter internodes; more importantly, leaf venation is clearly
palmate, and fruits are more spherical than elliptical. Our material does not seem
to be represented in Trelease (1916).
PANAMA: Along El Llano Carti-Tupile road, 12 mi above Pan-Am. Highway, primary
forest, 200-500 m, Liesner 1217 (MO, LEA).
19. Phoradendron sp.-FIG. 5.
A much branched, glabrous mistletoe with terete stems, some percurrent,
1978]
749


750
ANNALS OF THE MISSOURI BOTANICAL GARDEN
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[VOL. 65
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KUIJT-PANAMANIAN MISTLETOES
others forking through apical abortion; percurrent branches lacking cataphylls;
lateral branches with a single pair of white-margined cataphylls at the very base.
Leaves elliptical, to 5 cm long and 2 cm wide, the apex obtuse, the base tapered
into a short, flat petiole. Presumably dioecious; staminate plant or flowers not
seen. Pistillate spike ca. 2 cm long, with a single, short sterile internode and
4-5 fertile ones; fertile bracts usually with 3 flowers in la arrangement. Fruit
yellow, round, 2.5 mm wide, the petals closed, the floral cup conspicuous, the
apex of the spike blunt.
The pistillate spike provisionally placed in P. annulatum in my Costa Rican
revision (Kuijt, 1964) is more likely to belong with the present species, as
it has fewer flowers per internode than the type. The Panamanian specimen
cited below is clearly not related to P. annulatum. A peculiarity of this other-
wise undistinguished mistletoe seems to be that spikes never develop in the
axils of leaves, but only on older wood below. This feature and the terete
stems immediately differentiate this species from P. quadrangulare with which
it otherwise may be confused. The species is probably not included in Trelease's
treatment (1916).
PANAMA: Road to Campana, near Pan-American Highway, roadside field, Dwyer et al.
4340 (MO, LEA).
20. Phoradendron sp.--Fr. 6.
A glabrous, very stout and coarse plant, often forking through apical abor-
tion; branches terete, to 1.5 cm thick below, the leaf-bearing ones 4-5 mm thick
but to 10 mm thick at the leafy nodes; innovations of 2-5 internodes, ail but the
terminal node bearing pairs of large cataphylls, these more crowded toward the
base; percurrent branches similar. Terminal node with extremely leathery el-
liptical leaves, the blade to 10 cm long and 13.5 cm wide, with a thick, callused
margin and rounded apex, the base abruptly tapered into a massive petiole 3-5
mm wide, the venation palmate but usually obscure. Dioecious. Pistillate spikes
to 5 cm long, consisting of several sterile, basal internodes and ca. 5 fertile ones
with up to 18 flowers per internode in 3 series above each bract. Staminate
plants not seen.
This very distinctive species has not been previously reported from Central
America. It is related to P. obliquum, differing in having consistently more
cataphylls on both innovations and inflorescences, in having symmetrical rather
than falcate leaves, and in being apparently dioecious. The original description
of P. fendlerianum Eichler (Eichler, 1868) appears to match our material; the
type specimen was destroyed at Berlin-Dahlem, but its photograph survives in
Trelease's monograph (1916: pl. 211b).
PANAMA: Cerro Jefe, 1000 m, Mor et al. 3766 (MO, LEA); 2700-3000 ft, Tyson et al.
3193 (MO), 3282 (MO), 4340 (MO, LEA). VERAGUAS: 3-4 km by road W of Santa F�,
2500 ft, Nee 11316 (MO, LEA).
8. PHTHIRUSA Eichler, FI. Bras. 5(2): 52. 1868, non Mart. in Schult. & Schult.,
Syst. Veg. 7: 96. 1829.
1978]
751


752 ANNALS OF THE MISSOURI BOTANICAL GARDEN [VOL. 65
FIGURE 6.-Phoradendron sp. No. 20 (Mori & Kallunki 3766).


KUIJT-PANAMANIAN MISTLETOES
A rather large genus of uncertain distinction from Struthanthus, with two
species in Panama. One of these is the type species, P. pyrifolia, the only
Phthirusa north of Panama, reaching southern Mexico. In Rizzini's (1960) treat-
ment no mention is made of the fact that many (if not most) species of Phthirusa,
including the type species, have hermaphroditic flowers. However, there are
some close relatives of P. pyrifolia which are dioecious, so that sex distribution
alone cannot be used as a generic distinction. The other Panamanian species, P.
adunca, is such a dioecious one. A third species mentioned by Rizzini (1960),
P. pittieri, becomes a synonym of Struthanthus leptostachyus.
Critical literature: Rizzini, 1952; Kuijt, 1976b, Kuijt & Weberling, 1972.
a. Plants dioecious; flowers at least 4 mm long, pale yellow; inflorescence usually
branched .--- ....-- ...------- --- --.......... . ------1. P. adunca (Meyer) Maguire
aa. Plants with the flowers hermaphroditic; flowers less than 3 mm long, dark wine red;
inflorescence an unbranched spike or raceme ..------... . P. pyrifolia (H.B.K.) Eichler
1. Phthirusa adunca (Meyer) Maguire, Bull. Torrey Bot. Club 75: 301. 1948.
This species reaches its northern limits in Panama, being very common in
tropical South America.
2. Phthirusa pyrifolia (H.B.K.) Eichler, Fl. Bras. 5(2): 36. 1868.
While P. adunca develops roots on some branches, P. pyrifolia never does
so. Both species, however, produce long roots with secondary haustoria from the
base of the plant. The ovary of this species is solid, i.e., no ovarian cavity exists,
the embryo sacs developing in the central parenchymatous tissues. Other anatom-
ical peculiarities and a case for habitual autogamy in this mistletoe are pre-
sented by Kuijt & Weberling (1972). It is entirely possible that some of these
unusual features are shared by related species or even the genera Dendropomon
and Oryctanthus. Barlow & Wiens (1971) have found only tetraploids in Costa
Rica, but only diploids in Ecuador, so that both chromosome races could con-
ceivably occur in Panama.
9. PSITTACANTHUS Mart., Flora 13: 106. 1830.
This is the only large-flowered genus in Central America with flowers which
are at least partly red; the only other large, brightly colored mistletoe flowers
in the area are the golden yellow ones of Gaiadendron. The genus is distributed
from northern Mexico far into South America, with species on Jamaica, Marti-
nique, and Dominica.
Critical literature: Eichler, 1868.
a. Leaves lacking petioles, the base clasping the stem; lower inside petals with vermi-
form marginal appendages .-------.- -------------------.---- 3. P. hamulifer Kuijt
aa. Leaves petiolate; petals without vermiform marginal appendages.
b. Inflorescence axillary or on older wood, the smallest unit a pair of flowers
(diad); leaves mostly symmetrical.
c. Leaves usually in whorls of 4 (sometimes paired); anthers nearly sessile,
monomorphic, backed by a tuft of long, red hairs -----..... ---------.....
----.----------------------- ----. 4. P. nodosus (Desr.) G. Don
1978]
753


ANNALS OF THE MISSOURI BOTANICAL GARDEN
cc. Leaves 2 or 3 per node, or irregularly spaced, rarely in whorls of 4; anthers
on long filaments, dimorphic, hairless.
d. Flowers dilated at the base; leaves 7 cm long or more; petals not
plicate .------............... - . 1. P. allenii Woods. & Schery
dd. Flowers scarcely dilated at the base; leaves 6 cm long or less; petals
plicate at the tip ---. - ----.-.-.._.- _........ ...................... 5. P. pusillus Kuijt
bb. Inflorescence terminal, the smallest unit a triad; leaves falcate or at least tending
to be asymmetrical.
e. Mature buds 8-9 cm long, straight; leaves usually more than 6 cm wide
--------- -------................. ... .. __ _ 6. P. schiedeanus (Cham. & Schlecht.) Blume
ee. Mature buds about 4 cm long, slightly curved; leaves usually less than 5
cm wide -.-----.--.--..-....................... 2. P. calyculatus (DC.) G. Don
1. Psittacanthus allenii Woods. & Schery, Ann. Missouri Bot. Gard. 27: 309.
1940.
P. lateriflorus Woods. & Schery, Ann. Missouri Bot. Gard. 27: 309. 1940.
P. scheryi Woods., Ann. Missouri Bot. Gard. 28: 426. 1941.
The ligular differences to separate the above are not thought to warrant any
taxonomic recognition. Psittacanthus allenii is also extremely variable in its
leaf shape and size. It has been collected in southern Mexico, Nicaragua, Costa
Rica, and Panama. The closest relative of P. allenii seems to be P. dilatatus A. C.
Smith, the latter having much thicker buds and 1-1.5 mm long, erect, strap-
shaped ligules. Additionally, the stigma is situated below the anthers in P.
dilatatus, but above the anthers in P. allenii. Another closely related species is
P. dichrous (Mart.) Mart., of which authentic material has not been seen; the
excellent illustration in the Flora Brasiliensis 5(2), pl. 8. 1868 shows a crenulate
calyculus which P. allenii lacks. I have elsewhere remarked on the unusual
fact that seedlings of P. allenii in some areas are dicotyledonous, in others poly-
cotyledonous (Kuijt, 1970).
2. Psittacanthus calyculatus (DC.) G. Don, Gen. Syst. 3: 415. 1834.
P. chrismarii Urban, Bot. Jahrb. Syst. 24: 311. 1897.
Like P. schiedeanus, which it resembles somewhat, P. calyculatus ranges
north to southern Mexico but, unlike the former species, it also occurs in
Colombia and Venezuela. In the Costa Rica-Panama area, ail known collections
are from the Pacific slopes. While the two species are somewhat similar, the
leaf and bud characters used in the key provide a clear separation.
3. Psittacanthus hamulifer Kuijt, sp. nov.-FIG. 7.
Planta sat robusta; caules paulus applanati nec costati; intemodia usque ad 10 cm longa.
Folia coriacea, usque ad 15 X 7 cm, pinnatinervia, ovata ad late lanceolata, basi cordata,
amplexicaulia, apice acuta. Flores ut videtur in diadis; pedunculo pedicelloque cire. 5 mm
longis, gracillimis; calyculus margine crenatus; petala 5 cm longa, alabastro anguste acutato,
recta, laete aurantiaca, apice lutea; facies interior inferne (3 cm) seriebus marginalibus
appendicum vermiformium duabus, supra eas stamina 1.5 cm longa inserta; antherae 4.5 mm
longa, acumine aciformi 1 mm longo auctae, versatiles; stylus petala fere aequans; stigma
breviter clavatum, papillosum.
Stems only very slightly flattened, the internodes to 10 cm long. Leaves
coriaceous, to 15 cm long and 7 cm wide, pinnately veined with a very prominent
754
[VOL. 65


KUIJT-PANAMANIAN MISTLETOES
PI _ G C:E
e,
f::
1978]
755


ANNALS OF THE MISSOURI BOTANICAL GARDEN
midvein, ovate to broadly lanceolate, the base cordate and clasping, the apex
acute. Flowers (? only) in axillary positions, emerging from a "cushion" as in
Cladocolea (cf. Kuijt, 1975), apparently in diads; peduncle about 5 mm; pedicel
slightly longer, very slender, terminating in an oblique cup; petals 5 cm long, very
narrowly pointed in the straight bud, bright orange with a yellow tip, with 2
rows of fleshy, hook-shaped, marginal, frequently paired appendages up to 0.5
mm long inside for the lowest 3 cm, at which point filaments attached; stamens
1.5 cm long, the anthers 4.5 mm, narrow, versatile, with a needlelike tip about
1 mm long, and of 2 different lengths; ovary 4 mm long, 3 mm wide at the ir-
regularly scalloped calyculus; the style more or less straight, nearly the length
of the flower, the stigma papillate, clavate. Fruit not seen.
This is an exceedingly interesting species because of its flower structure. The
hooklike or vermiform appendages in what appears to be the tubular portion
of the corolla may either function in holding the nectar (see the com-
parable internal corolla modifications in the African Plicosepalus and Tapino-
stemma as illustrated in Engler & Krause, 1935: figs. 70-71); or possibly, as
their marginal position suggests, in linking the petals together. One other spe-
cies (Psittacanthus peronopetalus Eichl.) has been reported with similar ap-
pendages (Eichler, 1868), but that species differs in having petioled leaves, a
prominent ligule, apically diverging petals, and anthers lacking the needlelike
tip.
TYPE: PANAMA. DARI�N: On tree trunk in elfin forest, Cerro Pirre, cloud
forest and/or mossy forest, 2500-4500 ft, Duke & Elias 13681 (MO, holotype;
DUKE, SCZ, isotypes).
4. Psittacanthus nodosus (Desr.) G. Don, Gen. Syst. 3: 417. 1834.-FIc. 8.
Loranthus nodosus Desr. in Lam., Encycl. 3: 601. 1809.
Desrousseauxia nodosa (Desr.) Van Tieghem, Bull. Soc. Bot. France 42: 358. 1895.
Aethanthus nodosus (Desr.) Engler, in Engler & Prantl, Nat. Pflanzenfam., Nachtr. 1: 136.
1897.
Stems terete, the nodes swollen, the internodes up to 12 cm long. Leaves in
regular whorls of 4 (sometimes paired), to 8 cm long and 4 cm wide, rarely to
three times this size (Mori 8005), ovate or obovate to broadly lanceolate, with
a rough texture when dry. Inflorescences axillary, apparently consisting of
several diads on a common, red peduncle. Flowers bright red or orange below,
yellow above, 4-6 cm long in bud, the buds rounded at the apex, straight; calyx
scarcely or not at all dilated at the base; anthers all inserted at the same height,
5 mm below the petal tips, nearly sessile and backed by a crescent of long
reddish hairs; ovary 4 mm long, the style straight, with a small clavate stigma
just beyond anthers. Fruit dark purple, ca. 9 mm long and 5 mm wide, with an
inconspicuous calyculus.
The Central American material corresponds rather closely both to the original
description and to the Jussieu type at Geneva, collected in Ecuador, notwithstand-
ing the latter's more broadly ovate leaves. It should be noted, however, that
there is no mention in the original description of hairs associated with the anthers.
756
[VOL. 65


KUIJT-PANAMANIAN MISTLETOES
r
:4
k
*"'.'
cm
FI(GUR 8.-Psittacanthus nodosus (Desr.) G. Don (Luteyn & Foster 1122). From left to
right: flower; anther as seen from the back; tip of style; petal tip with anther removed
(broken line); and anther and petal tip from the side.
The species is also known from Costa Rica where it was treated as an unidenti-
fied species (No. 29) of Psittacanthus (Kuijt, 1964).
A specimen of uncertain identity is Gentry & Mori 14140 [Dari�n, central
ridge of Cerro Tacarcuna massif, 1700-1800 m (MO)]. It resembles the present
species except that the buds are slightly curved and unusually stout.
CHIRQUi: Nubes, 5.5 km NW of Rio Chiriqui Viejo, 2200 m, Busey 661 (MO). Las
Nubes, 5 km NW of Cerro Punta, 6000-6500 ft, Mori & Bolten 7233 (DUKE); Croat 26473
(MO, LEA). Rio Chiriqui Viejo, 2 km NE of Guadelupe which is 2 km N of Cerro Punta,
Wilbur et al. 15368 (DUKE, MO). COCL�: El Valle de Ant�n: Allen 2233 (US). El Valle
de Ant6n, La Mesa, Croat 14381 (MO). El Valle de Ant6n, Cerro Pilon, 2000 ft, Dwyer &
Correa 7995 (MO). COLON: La zona de Santa Rita, Correa & Dressler 1816 (MO). DARI�N:
Colombia (Choc6)-Panama (Dari�n) border, slopes of Serrania del Dari�n E of Ungia,
300-1300 m, Gentry et al. 16774 (MO). PANAMA: 8 km above Goofy Lake on road to
Cerro Jefe, Correa & Dressler 477 (MO). 1 mi beyond La Eneida, Cerro Jefe, Correa &
Dressler 971 (MO). Cerro Jefe, D'Arcy & D'Arcy 6248 (MO); Dwyer & Gauger 7334 (MO);
Dwyer & Hayden 8088 (MO); Gentry 6166 (MO); Gentry & Dwyer 5538 (MO). Near La
Eneida, 100 m, Luteyn & Foster 1122 (DUKE, MO). Cerro Jefe, 1000 m, Mori 8005 (MO);
Mori & Kallunki 3631 (MO). Above Goofy Lake on road to Cerro Jefe, Weaver & Foster
1496 (DUKE). VERAGUAS: 7 km NW on road to Santa F�, D'Arcy 10285 (MO). 3-5 mi N
of Santa F�, 500-1000 m, Gentry 2956 (MO). N of Santa F�, Mori & Kallunki 2599 (MO).
3-4 km W of Santa F�, 2500 ft, Nee 11318, 11320 (both MO).
1978]
757
�:
2i
::


ANNALS OF THE MISSOURI BOTANICAL GARDEN
5. Psittacanthus pusillus Kuijt, sp. nov.-FIG. 9.
Frutex parvus, gracilis; caules teretes; flores bini axillares, innovationibus ex internodiis
1-4 constantibus insidentes. Folia bina vel fere, elliptica ad late lanceolata, usque ad 6 X
2.5 cm, petiolis 1-3 mm longis. Diadae singulae in axillis; pedicelli 8-10 mm longi, cupula
ampliata terminati. Flos 30-40 mm longus; corolla 27-30 mm longa, recta vel paulum
curvata, aurantiaca, apice luteo vel viridescente; petala apice conspicue plicata, ligula minuta;
stamina dimorpha, ante anthesim haud imbricata.
A small and slender species, the stems terete and smooth with fine longi-
tudinal cracks in age, ca. 2 mm thick when flower bearing. Leaves paired but
sometimes irregularly spaced, elliptical to broadly lanceolate, to 6 cm long and
2.5 cm wide, the petiole 1 mm thick and 1-3 mm long, the apex rounded, the
base tapering into the petiole, only the midvein visible when dry. Flowers
axillary only, only on innovations 1-4 internodes long, in diads (rarely a triad),
these 1 per leaf axil, 3-4 cm long; peduncles 3-7 mm long, ca. 1 mm thick, often
consisting of 2 internodes lacking leaves, emerging from a craterlike axillary
rim of brown tissue; pedicels 8-10 mm long, ca. 1 mm thick, terminating in a
flaring cuplike structure 4 mm wide; corolla 27-30 mm long; the corolla tube
straight or slightly curved, 3-4 mm wide at the rounded tip, scarcely dilated be-
low, said to be orange with yellow or with a greenish apex, the petals con-
spicuously plicate at the tip, 6, the ligule very small; stamens dimorphic, slightly
shorter than the petals, the anthers versatile, 3 mm long, not overlapping in bud,
the filaments 12-15 mm long; ovary globose, ca. 3 mm in diameter, the calyculus
smooth, the style slender, 25 mm long, the stigma small, elliptical, with finely
papillate surface. Fruit unknown.
The closest relative of this species may be the Ecuadorian P. obovatus
(Benth.) Eichler which is similarly small leaved but has terminal inflores-
cences. I know of no other Psittacanthus flowering by means of such leafy in-
novations.
TYPE: PANAMA. PANAMA: In forest, about 1 mi upstream from Frizzel's
Finca Indio, on slopes of Cerro Jefe, Foster & Kennedy 1863 (DUKE).
Other material seen: PANAMA: Cerro Jefe, 2.5 mi beyond Finca Indio, Gentry 2108 (MO).
Road past Cerro Azul, 20 km from junction with road through Tocumen, Mori & Kallunki
2192 (MO). 8 km above Goofy Lake on road to Cerro Jefe, Weaver & Foster 1499 (DUKE).
6. Psittacanthus schiedeanus (Cham. & Schlecht.) Blume in Schult. & Schult.,
Syst. Veg. 7: 1730. 1830.
10. STRUTHANTHUS Mart., Flora 13: 102. 1830.
This is perhaps the most difficult genus in neotropical Loranthaceae, at least in
part because it seems to be polyphyletic (Kuijt, 1975). Especially the plants in
the marginatus-quercicola complex are often difficult to identify. In this regard,
the present treatment is little more than an extrapolation of my Costa Rican
treatment (1964).
Critical literature: Eichler, 1868; Kuijt, 1964.
758
[VOL. 65


KUIJT-PANAMANIAN MISTLETOES
b a
'ib cm
I/"
FIGURE 9.-Psittacanthus pusillus Kuijt, type (Foster & Kennedy 1863).-a. Habit and
floral details.-b. Axillary cushion at base of diad.
a. Each flower supported by 1 bract and 2 bracteoles, these monads paired along the
raceme axis ------- --- 5. S. panamensis (Rizz.) Barlow & Wiens
aa. Flowers in triads, these with 1 bract and 2 bracteoles and paired along the raceme
axis.
b. Stem (often also inflorescence axis) dotted with large lenticels; inflorescence
subtended by persistent papery bracts ..---- - 2. S. leptostachyus (H.B.K.) G. Don
bb. Stems lacking obvious lenticels; inflorescence without persistent papery bracts.
c. Bracteoles of female flowers stout and persistent.
d. Mature fruit dark blue, more than 7 mm long; some young leaves
prehensile ---- ----------------- --------- 7. S. rotundatus Rizz.
dd. Mature fruit reddish orange, less than 7 mm long; leaves never pre-
hensile -_.. ....------------ 6. S. quercicola (Cham. & Schlecht.) Blume
1978]
759


ANNALS OF THE MISSOURI BOTANICAL GARDEN
,c. Bracteoles of female flowers delicate and deciduous.
e. Young leaves prehensile, on somewhat quadrangular stems; fruit blue
when mature, at least 1 cm long, on swollen pedicel with lenticels
-..Y..--..v..e. s n... .. . ... --------.. . ... .........- - . 4. S. orbicularis (H.B.K.) Blume
ee. Young leaves not prehensile, on terete stems; fruit reddish to yellow,
less than 1 cm long, the pedicel not conspicuously swollen.
f. Inflorescence axis very delicate, sometimes with no more than 4
triads; triad peduncle 2-3 mm long; fruit 5 mm long, 3 mm wide;
leaves commonly 3 or more times as long as wide, with a very
attenuate apex . ....-------. ---------..----. 1. S. aff. dichotrianthus Eichler
ff. Inflorescence axis not particularly delicate, always with more than
6 triads; triad peduncle 2 mm long or less; fruit 7 mm long, 5 mm
wide; leaves usually less than 3 times as long as broad, the apex
not or scarcely attenuate ......._-------- 3. S. marginatus (Desr.) Blume
1. Struthanthus aff. dichotrianthus Eichler, Fl. Bras. 5(2): 75. 1868.
Scandent shrub with terete stems and stem-roots. Leaves paired, thin, 7-11
cm long, 1.5-4.5 cm wide, including a 2-5 mm, tapering petiole, the blade ovate
to lanceolate, with a slender, attenuate tip. Inflorescence very slender, 1 or 2
per axil; peduncle up to 1 cm long, with 2 or 4(-10) triads each on peduncle of
similar length. Flowers not seen. Fruit oblong to spherical, to 4 mm long and
5 mm wide, yellow to bright orange, the median one sessile, the lateral ones on
pedicels nearly 2 mm long.
It is possible that this material corresponds to what has been referred to as
Struthanthus No. 37 (Kuijt, 1964); certainly Fig. 37 in that article illustrates the
habit of the Panamanian material. The D'Arcy collection is very narrow-leaved,
and its inflorescences are also more elongate than the Cocl� material. Finally
the Luteyn collection has up to 10 triad pairs per inflorescence. Whether all
this material [plus the von Wedel 1287 (GH) mentioned in Kuijt (1964: 301)]
constitutes a single variable species, or whether ail are variants of S. marginatus
remains an open question.
BOCAS DEL TORO: Between Buena Vista coffee finca and Cerro Pilon, Kirkbride & Duke
709 (LEA, MO). cocai: Foothills of Cerro Pilon, near El Valle, 900 m, Duke & Correa
14673 (MO). Cerro Caracoral, 900 m, Duke & Dwyer 15131 (MO). La Mesa, above El
Valle, Dwyer 11862 (LEA, MO). Foot of Cerro Pilon, above El Valle de Anton, 2000 ft,
Porter et al. 4409 (LEA, MO). VERAGUAS: 7 km NW on road to Santa F�, D'Arcy 10280
(MO). ? NE slopes of Cerro Delgadito, just NW of Cerro Tut�, S of town of Santa F�,
1000 m, Luteyn 4024 (DUKE).
2. Struthanthus leptostachyus (H.B.K.) G. Don, Gen. Syst. 3: 411. 1834.
Loranthus leptostachyus H.B.K., Nov. Gen. Sp. PI. 3:440. 1818.
L. pyrifolius Willd. in Schult & Schult., Syst. Veg. 7: 1647. 1830, non H.B.K.
Peristethium leptostachyum (H.B.K.) Van Tieghem, Bull. Soc. Bot. France 42: 175. 1895.
Phthirusa pittieri Krause, Repert. Spec. Nov. Regni Veg. 15: 441. 1919.
This species is not to be confused with: Viscum leptostachyum Spreng. in DC., Prodr.
4: 280. 1830 = Dendrophthora leptostachya (Spreng.) Eichler, Fl. Bras. 5(2): 104. 1868 =
Phoradendron leptostachyum (Spreng.) Index Kew. 3: 502. 1894 = Dendrophthora flagelli-
formis (Lam.) Krug & Urban.
This common species has frequently been referred to as S. polystachyus (Ruiz
& Pav6n) Blume, as in Rizzini's (1960) and my own (Kuijt, 1964) treatments.
760
[VOL. 65


KUIJT-PANAMANIAN MISTLETOES
The type of Loranthus polystachyus Ruiz & Pav6n, however, has leaves which
are consistently different in shape from Central American material, which almost
certainly is specifically distinct. In Central America this mistletoe is unique in
having a cluster of persistent, papery scale leaves which invests the base of each
inflorescence, and in the fact that the tip of the inflorescence, instead of the
usual triads of flowers, has single flowers, and even terminates in a single flower
(Kuijt, 1964). On the basis of the scale leaves (and supposed hermaphroditic
flowers: the flowers are in reality unisexual, the plants dioecious as elsewhere
in Struthanthus), Van Tieghem (1895) erected the monotypic genus Peristethium.
Struthanthus leptostachyus appears to be closely related to Cladocolea archeri
(A. C. Smith) Kuijt, confronting us with a nettly taxonomic problem at the
generic level (Kuijt, 1975). In the limited sense, this species ranges from Costa
Rica as far as Ecuador.
The collection Tyson et al. 3233 [Panama, Cerro Jefe in Clusia forest, 2700-
3000 ft (MO)] is a very small-leaved specimen. Its relationship to S. lepto-
stachyus is clear, but it may represent an undescribed species.
3. Struthanthus marginatus (Desr.) Blume in Schult. & Schult., Syst. Veg.
7: 1731. 1830.
Equivalence of Central American S. marginatus to the type material from
eastern Brazil is by no means certain, but cannot be ascertained at this time.
4. Struthanthus orbicularis (H.B.K.) Blume in Schult. & Schult., Syst. Veg.
7: 1731. 1830.
This is one of several species of Struthanthus which uses its young leaves in
a prehensile fashion. It is not synonymous with S. rotundatus as previously
indicated (Kuijt, 1964). This species ranges from southern Mexico into Brazil
and Peru. See comments under S. rotundatus.
5. Struthanthus panamensis (Rizz.) Barlow & Wiens, Brittonia 25: 39. 1973.
Phrygilanthus panamensis Rizz., Ann. Missouri Bot. Gard. 47: 270. 1960.
This enigmatic species had earlier been thought to be related to Phrygi-
lanthus palmeri Watson which, however, was relegated to Psittacanthus by Bar-
low & Wiens (1973). The indicated affinity is out of the question, but the
generic status of the species remains uncertain. It might be added that the
genus Phrygilanthus has been totally dissolved for nomenclatural and other
taxonomic reasons (Barlow & Wiens, 1973). The present species may be out of
place in Struthanthus because of its apparently hermaphroditic flowers and
the one-flowered inflorescence unit rather than the triads of other species of
Struthanthus.
CHnIQUi: Bajo Chorro, Boquete District, 1800 m, Davidson 431 (US, holotype; A, F,
isotypes); Davidson 392 (US). NE ridge leading to Cerro Horqueta, 1800-1900 m, Luteyn
3786 (DUKE). Cerro Colorado, 50 km N of San Felix, 1200-1500 m, Mori & Dressler 7825
(MO). Chiriqui Viejo ca. 2 mi NE of Cerro Punta, 7000 ft, Wilbur & Teeri 13109 (DUKE).
1978]
761


ANNALS OF THE MISSOURI BOTANICAL GARDEN
6. Struthanthus quercicola (Cham. & Schlecht.) Blume in Schult. & Schult.,
Syst. Veg. 7: 1731. 1830.
Scandent green shrub with epicortical roots, the stems smooth but often some-
what ridged when young, grey. Leaves petiolate, ca. 10 cm long and 4 cm wide,
ovate, usually thin, the apex attenuate. Inflorescences 1-6 per axil, to 50 cm long,
then with about 36 flowers in triads with 2-3 mm long stalks; median flower
sessile, the lateral ones nearly so; bracts persistent in pistillate flowers, becoming
somewhat fleshy in fruit, deciduous at least in some staminate flowers. Flowers
light green or yellowish, 4 mm across when expanded; petals 2 mm long; stamens
shorter, dimorphic, the anthers brownish yellow; style 2 mm long. Fruit an
orange berry, elliptical to ovoid, 4 mm long, 6 mm wide, supported by somewhat
swollen, short pedicels (lateral flowers) or sessile (median flower).
The species is based on a type from Mexico (Jalapa) and is especially com-
mon in Costa Rica (Kuijt, 1964). Some of the collections cited earlier (Rizzini,
1960) under S. marginatus in reality belong here. Only some representative
specimens are cited below.
BOCAS DEL TORO: Along RR near station at Milla 10, Croat 16339 (LEA, MO). CHnuQUi:
Along Rio Chiriqui Viejo just above Guadelupe, Croat 16036 (LEA, MO). E slope of Volcan
de Chiriqui (Baru), 2200-2300 m, Davidse et al. 10185 (LEA, MO). Cerro Respinga, E of
town of Cerro Punta, 2000-2500 m, Gentry 5944 (LEA, MO). W side of Cerro Horqueta,
1700-1800 m, Luteyn 3759 (DUKE). 2 km W of La Garita about 3 km WNW of Cerro
Punta, 2000 m, Wilbur et al. 15286 (DUKE). Ca. 6 mi NW of Boquete, 1450 m, Wilbur
et al. 11970 (DUKE). DAMI�N: S slope of westernmost peak of Cerro Tacarcuna massif,
1100-1300 m, Gentry et al. 16874 (MO). LOS SANTOS: 4 mi S of Limon, Correa et al. 68
(MO). VERAGUAS: N of Santa F�, on property of Escuela Agricola Alto de Piedra, Mori &
Kallunki 2606 (LEA, MO).
7. Struthanthus rotundatus Rizz., Revista Brasil. Biol. 10: 401. 1950.
This is a clearly distinct species which I erroneously referred to S. orbicularis
(Kuijt, 1964), to which it is nevertheless closely related. The young leaves are pre-
hensile as in S. orbicularis. The two species may be separated in that S. ro-
tundatus is generally larger in habit and inflorescences; this species has con-
spicuous floral bracts and bracteoles which persist in fruit, while those of S.
orbicularis are small and caducous; the fruiting peduncles of S. orbicularis are
greatly swollen and show large lenticels, those of S. rotundatus are not so swollen
and lack lenticels. Finally, the mature fruits of S. rotundatus are said to be
orange while those of S. orbicularis, even though passing through a brick red
phase, are dark blue when ripe. The present species was originally described
from Brazil.
LITERATURE CITED
BARLOW, B. A. 1964. Classification of the Loranthaceae and Viscaceae. Proc. Linn. Soc.
New South Wales 89: 268-272.
- & D. WIENS. 1971. The cytogeography of the Loranthaceous mistletoes. Taxon
20: 291-312.
- & . 1973. The classification of the generic segregates of Phrygilanthus
(= Notanthera) of the Loranthaceae. Brittonia 25: 26-39.
EICHLER, A. W. 1868. Loranthaceae. In C. F. P. Martius, Flora Brasiliensis 5(2): 1-135.
[VOL. 65
762


1978] KUIJT-PANAMANIAN MISTLETOES 763
ENGLER, A. & K. KRAUSE. 1935. Loranthaceae. In A. Engler & K. Prantl, Die Natirlichen
Pflanzenfamilien. Ed. 2, 16b: 98-203.
KUIJT, J. 1959. A study of heterophylly and inflorescence structure in Dendrophthora and
Phoradendron (Loranthaceae). Acta Bot. Neerl. 8: 506-546.
. 1961a. Notes on the anatomy of the genus Oryctanthus (Loranthaceae). Canad.
J. Bot. 39: 1809-1816.
1961b. A revision of Dendrophthora (Loranthaceae). Wentia 6: 1-145.
1963a. On the ecology and parasitism of the Costa Rican tree mistletoe, Gaia-
dendron punctatum (Ruiz & Pav�n) G. Don. Canad. J. Bot. 41: 927-938.
1963b. Dendrophthora: additions and changes. Acta Bot. Neerl. 12: 521-524.
1964. A revision of the Loranthaceae of Costa Rica. Bot. Jahrb. Syst. 83: 250-326.
1967. The genus Ixocactus (Loranthaceae, s.s.): description of its first species.
Brittonia 19: 61-66.
1968. Mutual affinities of Santalalean families. Brittonia 20: 136-147.
1970. Seedling establishment in Psittacanthus (Loranthaceae). Canad. J. Bot.
48: 705-711.
.1975. The genus Cladocolea (Loranthaceae). J. Arnold Arbor. 56: 265-335.
1976a. Revision of the genus Oryctanthus (Loranthaceae). Bot. Jahrb. Syst. 95:
478-534.
.1976b. Proposal for the conservation of the genus name Phthirusa Eichler (1868)
over Phthirusa Martius (1830) and Passowia Karsten (1852). Taxon 25: 196-197.
& F. WEBERLING. 1972. The flower of Phthirusa pyrifolia (Loranthaceae). Ber.
Deutsch. Bot. Ges. 85: 467-480.
RrZZINI, C. T. 1952. Phthirusae Brasiliae terrarumque adiacentium. Dusenia 3: 451-462.
.1956. Pars specialis prodromi monographiae Loranthacearum Brasiliae terrarumque
finitimarum. Rodrigu�sia 28-29: 87-264.
.1960. Loranthaceae. In R. E. Woodson, Jr. & R. W. Schery, Flora of Panama.
Ann. Missouri Bot. Gard. 47: 263-290.
STANDLEY, P. C. & J. A. STEYERMARK. 1946. Loranthaceae. In Flora of Guatemala. Fieldiana,
Bot. 24(4): 62-86.
TRELEASE, W. 1916. The Genus Phoradendron. Univ. of Illinois, Urbana.
1940. Phoradendron. In R. E. Woodson, Jr. & R. W. Schery, Contributions towards
a flora of Panama. Ann. Missouri Bot. Gard. 27: 307-309.
VAN TIEGHEM, P. 1895. Sur le groupement des esp�ces en genres dans les Loranth�es �
calyce dialys�pale et anth�res oscillantes ou Struthanth�es. Bull. Soc. Bot. France 42:
161-180.