Philodendron Subgenus Pteromischum (Araceae) from Saiil,
French Guiana
Thomas B. Croat and Michael H. Grayum
Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166, U.S.A.
ABSTRACT. This paper treats the six species of
Philodendron subg. Pteromischum from Saiil, a
region of mostly virgin humid forest located in cen-
tral French Guiana. Descriptions, dichotomous keys,
discussion, and exsiccatae are provided. Three spe-
cies, P. cremersii, P. duckei, and P. guianense,
are new.
Work toward the completion of the Araceae treat-
ment for the Flora of Saiil has resulted in the res-
olution of several unidentified species of Philoden-
dron subg. Pteromischum from the Guianas. This
treatment is to appear in a work currently in prep-
aration by Scott Mori et al. entitled Flora of the
Central French Guiana: A Manual of the Vascular
Plant Families of Lowland Moist Forest in North-
eastern South America, to be published by the New
York Botanical Garden. The publication schedule of
that treatment demands the publication of several
novelties at this time. Because subgenus Pterom-
ischum is very rich and confusing in the Guiana
region, and the Flora of Saill treatment does not
allow detailed descriptions, the publication of de-
tailed descriptions for all the species in the Sail
region is warranted.
KEY TO SPECIES OF SAULIAN PHILODENDRON SUBG. PTEROMISCHUM
la. Leaf blades lacking any obvious primary lateral veins; entire spathe abscissing immediately after anthesis
..... ...... ......................................... ........ . P. surinam ense (M iquel) Engler
lb. Leaf blades with obvious primary lateral veins (at least near the base); spathe persisting after anthesis (at
least until maturity of fruits).
2a. Leaf blades more than 30 cm long and usually more than 13 cm wide (more than 6.5 cm wide in
juveniles); spathe 14-17 cm long ................................. P. cremersii Croat & Grayum
2b. Leaf blades less than 23 cm long and usually less than 12 cm wide; spathe 6-12.5 cm long.
3a. Petiole sheath ending somewhat below the base of the blade ....... P. guianense Croat & Grayum
3b. Petiole sheath ending at base of blade.
4a. Petioles so narrowly winged as to almost appear unwinged, the wing erect or involute, 3-4
mm wide when flattened; blades dark green and velvety above; stems distinctly scaly-puberulent
or scaberulous ........................... ............ P. duckei Croat & Grayum
4b. Petioles conspicuously winged, the wing spreading, 9-10 mm wide; blades medium green and
semiglossy to glossy above; stems smooth or at most minutely granular-puberulent at 30 x
magnification.
5a. Blades glossy on lower surface; plants nearly always growing up tree trunks in a spiral
fashion, usually producing 2 3 spirals before branching and flowering; spadix slender
.............................................................. P . p lacidum Schott
5b. Blades matte on lower surface; plants usually growing straight up the side of tree trunks
before branching and flowering; spadix stout ..................... P. rudgeanum Schott
Philodendron cremersii Croat & Grayum, sp.
nov. TYPE: French Guiana. Montagnes de Kaw,
along road to Montagne Favard, in vicinity of
junction to Fourgrassie, 04�38'N, 52�17'W,
200 m, Croat 74336 (holotype, M0-4343662;
isotypes, B, CAY, F, K, MG, NY, P, US, VEN).
Figures 1, 2.
Planta hemiepiphytica; internodia 1-9(17) cm longa;
petiolus (6)13-27 cm longus, vaginatus usque 1.2-1.7
cm infra laminam; vagina erecta; lamina plus minusve
elliptica, 30-50.5 cm longa, 9-20 cm lata, nervis pri-
mariis lateralibus ca. 20 utroque; pedunculus usque 3 cm
longus; spatha 14-17 cm longa; spadix 11-16.5 cm
longus; parte pistillata usque 5 cm longa.
Hemiepiphyte, on tree trunks near the ground.
Stems sometimes trailing when preadult, appressed-
climbing when adult. Internodes 1-9(17) cm long,
(0.5)1-1.5 cm diam., dark green to bluish green,
matte to weakly glossy, flattened on one side, drying
light yellow-brown to medium reddish brown, drying
NOVON 4: 211-219. 1994.


Novon
1 I
Figures 1, 2. Philodendron cremersii Croat & Grayum,
erect-incurled sheath and short-pedunculate inflorescence.
narrowly ridged (sometimes irregularly so on juve-
niles). Petioles to 27 cm long, sheathed to within
1.2-1.7 cm of the base of the blade on adult plants
(to beyond the base of the blade on juveniles); sheath
narrow (the sides ca. 5 mm high), to 10 mm or
more wide when flattened, erect-incurled, overlap-
ping at base, erect and incurled toward apex, emar-
ginate and free-ending at apex, dark green and
matte, the surface drying finely striate. Blades some-
what inequilateral, one side 0.5-4.3 cm narrower,
+ elliptic, rarely narrowly oblanceolate, 6.5-21 cm
long, 6.5-13 cm wide when young, usually narrowly
oblanceolate, 30-50.5 cm long, 9 20 cm wide, ca.
3 times longer than wide (rarely as little as 1.8 times
longer than wide), acuminate at apex, equilateral or
only slightly inequilateral and acute to narrowly
rounded at base, subcoriaceous, dark green and
subvelvety matte when young, becoming weakly
glossy when mature, moderately paler and semi-
glossy below (matte when juvenile), becoming semi-
glossy, usually drying dark brown above, lighter
brown below; margins broadly undulate; midrib ob-
tusely sunken and concolorous to slightly paler above,
narrowly raised below (sometimes convex on juve-
niles) and paler below. Primary lateral veins to ca.
20 per side on adults (5-9 on juveniles), arising at
Croat 74336. --1. Habit. -2. Flowering plant showing
55-80� angle (45-55� on juveniles), weakly arcuate,
weakly quilted-sunken above, weakly raised to con-
vex and paler below, sometimes weakly pleated,
drying darker than surface below. Minor veins sparse,
moderately distinct below, drying weakly raised and
somewhat undulate with rather prominent oblique
cross veins. Inflorescences 1-2 per axil. Peduncle
to 3 cm long, largely hidden by the spathe. Spathe
14-17 cm long, slightly constricted above the tube.
Spathe tube medium green outside, blade pale green
to whitish, the entire inner surface greenish white.
Spadix 11-16.5 cm long; female portion of spadix
pale green, to 5 cm long in front, 4.7 cm long in
back, to 2 cm diam. midway, 1.8 cm diam. at apex,
1.7 cm diam. at base.
Philodendron cremersii is apparently endemic to
French Guiana, known principally from the Mon-
tagnes de Kaw at 100-250 m. It is common along
the road to Montagne Tresor east of Cayenne. It is
also known from a single collection along the road
between Cayenne and Regina.
The species is recognized by its very large, dark
brown-drying leaf blades, erect petiole sheath ex-
tending nearly to the apex, yellowish brown-drying
stem, and the semiglossy upper blade surfaces. It is
212


Volume 4, Number 3
1994
Croat & Grayum
Philodendron subg. Pteromischum
named in honor of Georges Cremers, a long-time
researcher at ORSTOM in French Guiana. He has
made many excellent collections of Araceae, in-
cluding the first collection of this species.
Plants believed to represent P. cremersii are also
relatively common around Eaux Claires near Sail
in central French Guiana, but were seen only in
sterile and probably juvenile condition on the lower
trunks of trees in the forest understory. The Saiil
material (Croat 74165 and 74234) differs in having
blades that are subvelvety above and matte below
(drying gray-green above, slightly yellow-green be-
low, with the epidermal cells sunken on both sur-
faces), in contrast to weakly glossy for the fertile
collections seen in the Montagnes de Kaw. It is likely
that these differences are merely due to age.
Philodendron cremersii is similar to P. macro-
podum K. Krause described from Brazil (Roraima:
Serra de Mairary at 1,000 m). That species also
has a petiole sheath that ends somewhat below the
blade, but it has smaller leaves which are more
nearly elliptic and dry gray-brown above and reddish
brown below. In addition, they are broadly rounded
at the base (vs. narrowly rounded to acute for P.
cremersii).
Philodendron cremersii is easily confused with
another incompletely known but apparently new spe-
cies from French Guiana and Surinam. That species
has blades that are typically more ovate, averaging
about twice as long as broad (vs. an average of 2.5
times longer than broad in P. cremersii). It also
differs in having blades that are matte when fresh
(also expressed in larger epidermal cells on the upper
surface of the blade), which dry yellowish brown
rather than dark brown and lack the oblique cross
veins common to P. cremersii. The species is rep-
resented by material from Ile de Cayenne (Oldeman
1117), Montagnes de Kaw (Billiet & Jadin 1986,
Cremers & Feuillet 1970, Croat 74254), and along
the St. Elie track (Croat 53849). It is probably also
represented in Surinam at Brownsberg Park (Croat
53902).
Paratypes. FRENCH GUIANA. Montagnes de Kaw,
100 m, Cremers 9828 (B, CAY, K, NY, P, U, US);
Montagnes de Kaw, caves of Kaw, along road to Montagne
Tresor, ca. 10 km E of Camp Caimans, 4�34'N, 52010'W,
100 m, Croat 74270 (CAY, MO); along road to Montagne
Tresor, caves of Kaw, ca. 10 km E of Camp Caiman, 5
km N of road, 100 m, 4�34'5"N, 52�10'00"W, Croat
74254 (CAY, MO); Montagnes de Kaw, N slope, 2-3
km N of Camp Caiman, 100 m, de Granville 6700 (CAY);
Montagnes de Kaw, along road to Montagne Favard, vic.
jet. to Fourgrassie, 4�38'N, 52�17'W, 200 m, Croat
74336 (B, CAY, F, K, MG, MO, NY, P, US, VEN);
Cayenne-Regina, km 93, 100-150 m, Croat 74322
(MO).
Philodendron duckei Croat & Grayum, sp. nov.
TYPE: French Guiana. Mt. Galbao, south sec-
tor, 570 m, 3�35'N, 53�18'W, de Granville
et al. 8894 (holotype, US; isotypes, CAY, K,
NY, P). Figures 3, 4.
Planta hemiepiphytica; internodia 1-5(8) cm longa,
3.5 mm diam.; petiolus 3-7 cm longus, omnino vaginatus;
lamina oblongo-elliptica, 6.5-21 cm longa, supra hebe-
tata, subvelutinave; nervis primariis lateralibus 9-13 ut-
roque; inflorescentia solitaria; pedunculus 1.5-2 cm lon-
gus; spatha 7-8 cm longa; spadix 6.5-8 cm longus, parte
feminina 2.2 cm longa.
Terrestrial or hemiepiphytic near the ground. In-
ternodes purplish to brownish, semiglossy, terete, 1-
5(8) cm long, 3-5 mm diam., drying dark brown,
sharply ribbed, densely and minutely scaly-scaber-
ulous (sometimes smooth in age; merely scaberulous
in material from Sail). Petioles 3-7 cm long, sheathed
throughout, the sheath matte, erect and incurled,
3-4 mm wide when flattened, closely striate, the
striae and lower part of lower midrib often densely
scaberulous, sheath apex rounded and slightly over-
lapping base of blade. Blades slightly inequilateral,
one side 7-11 mm narrower, oblong-elliptic, 6.5-
21 cm long, 2.5-7 cm wide, gradually acuminate
at apex, acute to narrowly rounded or weakly cor-
dulate at base, thin, dark green, matte and subvel-
vety above, slightly paler and matte below, drying
grayish to olive-green above, yellowish gray-green
to yellowish brown below. Major veins sunken above,
slightly paler and matte below; major veins raised
below. Midrib and primary lateral veins sunken above;
midrib prominently raised and slightly paler below,
drying brownish; primary lateral veins 9-13 pairs,
arising at 50-60� angle, weakly arcuate to margin,
� pleated-raised below, drying slightly paler than
the surface. Minor veins fine, distinct. Inflorescence
1 per axil. Peduncle 1.5-2 cm long, less than 3
mm diam. when dried. Spathe 7-8 cm long, 7-15
mm diam., weakly constricted just above the tube,
the tube 1.5-1.7 cm diam. Spadix 6.5-8 cm long,
the pistillate part 2.2 cm long, 6 mm diam.; sta-
minate portion to 3.2 cm long, < 3 mm diam. on
drying throughout. Infructescence 2.5-3.5 cm long,
drying 10-15 cm diam.
The species ranges from French Guiana to north-
eastern Brazil (Amapa and Para) to as far south as
4�11'S, at elevations of 60 to 580 m. It is char-
acterized by its thin, subelliptic, dark green blades
subvelvety on the upper surface and the slender,
fully winged petiole. It was first collected in French
Guiana by Joseph Martin. It is named in honor of
Adolfo Ducke, who made important collections in
the Amazon basin between 1912 and 1947. He was
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Volume 4, Number 3
1994
Croat & Grayum
Philodendron subg. Pteromischum
the first to have collected this species in Brazil (19
November 1910).
Paratypes. BRAZIL. Amapa: Municipio Oiapoque,
121 km SSE of Oiapoque on BR 156, near edge of
Reserva Indigena Uaca, ca. 3�00'N, 51�30'W, Daly &
Souza 3830 (NY). Para: BR 422, 70 km SSW of Tuc-
urui, 4�11'S, 49�44'W, Daly et al. 1494 (MG, MO); Rio
Tocantins, Igarape Cameta6, entrance Itupiranga, 4�09'S,
49�17'W, Daly et al. 1562 (MG); Santarem, km 61
along road to the Palhao waterfalls, on Rio Curua, Rio
Gumini-Mirim, Castenhal das Piedras, Ducke 11471(MG).
FRENCH GUIANA. Locality unknown: Martin s.n. (K,
mistakenly labeled type of P. guttiferum var. rudgean-
um); Approuague river basin-Arataye, 403'N, 52�42'W,
90 m, Larpin 803 (CAY, MO); Camopi River (tributary
of Oyapock), 2 km from Crique Tamouri, Oldeman 143
(CAY, P); Camopi River, Saut Ouasseye, Oldeman 2603
(CAY, P); Gobaya Soula-Maroni River basin-trail to Ata-
chi-Bacca, l'Itany River, de Granville 10392 (CAY);
Mont Galbao, 570 m, 3�35'N, 53�18'W, de Granville
et al. 8894 (CAY, US); lie de Cayenne, Mont Grand
Matoury, 50 m, Cremers 1993 (CAY, MO); Oyapock
River, 2 km from Camopi, Oldeman 2732 (CAY, P),
2737 (CAY,P); Montagne Bellevue de l'Inini, 700 m, de
Granville 7981 (CAY); Region de Paul Isnard, Massif
du Decou, 580 m, Feuillet 389 (CAY, K); Saut Parare,
Arataye River, affluent of Approuague River, 7 km SW
of Regina, Villiers 2720 (CAY); Saiil, Riera 947 (CAY);
Saiil, ORSTOM trail, Boef Mort trail, p.k. 1,200, de
Granville 894 (CAY, P, US); Sail, vic. Eaux Claires,
Croat 74142 (CAY, MO), 74185 (CAY, MO); Yaroupi
River, Saut Polissoirs, Oldeman 3062 (CAY); Yaroupi
River, 6 km from Saut Tainoua, de Granville 395 (CAY).
SURINAM. Massau Mts., Marowijne River, 400-520 m,
Cowan & Lindeman 39024 (NY).
Philodendron guianense Croat & Grayum, sp.
nov. TYPE: Surinam. Emmaketen Mountains,
south track, ca. 1 km S of division point, cloud
forest, 825 m, Daniels & Jonker 1061 (ho-
lotype, NY; isotypes, K, U). Figures 5, 6.
Planta hemiepiphytica; internodia 2-6 cm longa, 3-5
mm diam.; petiolus 6.5-10.5 cm longus; vagina terminans
6-15 cm infra laminam; lamina oblonga-elliptica vel an-
guste obovata, 9-21 cm longa, 3-7.5 cm lata; nervis
primariis lateralibus 3-5(7) utroque; pedunculus 2.5-3
cm longus; spatha 6-8 cm longa, non constricta supra
tubum, viridis vel flavum omnino; spadix 5-7.5 cm longus,
parte pistillata 2-3.7 cm longa.
Hemiepiphytic vine. Internodes 2-6 cm long, 3-
5 mm diam., dark green to olive-green or grayish,
turning light brown, semiglossy, weakly flattened on
one side, drying light yellow-brown to dark brown.
Petioles 6.5-10.5 cm long, medium green and weak-
ly glossy, darker along the margins, sheathed from
% its length to nearly throughout but ending 6-15
mm below the blade, sometimes to the base of the
geniculum, narrow, erect and incurled, the margins
touching toward the base, typically less than 5 mm
high, to ca. 8 mm wide when flattened (to 1 cm
wide when subtending inflorescence), narrowly
rounded at the apex, the free portion of the petiole
and the geniculum sharply sulcate. Blades thinly
coriaceous, slightly to moderately inequilateral, ob-
long-elliptic to narrowly obovate, 9-21 cm long, 3-
7.5 cm wide, gradually to abruptly acuminate at
apex, slightly inequilateral and acute at base, sub-
coriaceous, dark green and weakly subvelvety matte
to weakly glossy above, slightly to moderately paler
and matte below, drying gray-green above, yellow-
green below. Midrib deeply sunken and concolorous
above, narrowly convex and slightly paler below.
Primary lateral veins 3-5(7), weakly visible and
weakly sunken above, flat and weakly pleated-raised
below, scarcely more visible than minor veins (only
slightly wider at times), arising at 45-50� angle,
drying paler than surface, sometimes weakly un-
dulate, gradually arcuate to margins. Minor veins
visible but usually weak and thin. Inflorescence sol-
itary. Peduncle slender, mostly exposed, 2.5-3 cm
long, drying less than 3 mm diam., reddish brown.
Spathe 6-8 cm long, 1-2 cm diam., not at all
constricted above the tube, solid green to yellowish,
slightly paler within, drying reddish brown. Spadix
5-7.5 cm long. Pistillate portion 2-3.7 cm long,
8-10 mm diam. Staminate portion weakly protruded
forward, slender, with a small portion remaining
exposed on drying.
Philodendron guianense ranges from Guyana
(doubtless Venezuela as well since it has been col-
lected very near the Venezuelan border (Stergios
et al. 3371)) to Surinam, French Guiana, and Brazil
(Amapa at 2�12'N), 100-900 m elevation.
Steyermark 87586 from Venezuela (Delta Ama-
curo, Rio Cuyubini, Cerro La Paloma in the Sierra
Imataca at 100-200 m) is perhaps also this species.
However, it differs in having the petioles sheathed
all the way to the geniculum.
The species is characterized by its usually oblong-
elliptic, frequently subvelvety matte blades, petiole
sheath ending somewhat below the leaf blade, and
inflorescence with a small apical portion remaining
exposed after drying. The name of the species re-
flects its primarily Guianan distribution.
215
4-
Figures 3-6. 3, 4 Philodendron durkei Croat & Grayum, Croat 74142. -3. Habit. -4. Showing narrowly
sheathed petiole and matte blade. 5, 6. P. guianense Croat & Grayum, Croat 74235. -5. Habit, growing over
large rock. -6. Habit, growing over ground.


Novon
Some collections (Grenand 1626 (CAY) collected
at Oyapock: Anse Bruyere and Daniels 48 (CAY)
collected at Grand Santi) were collected on opposite
sides of French Guiana. They are tentatively placed
here but perhaps represent another species. They
differ in having narrower blades that dry dark brown
and have primary lateral veins departing the midrib
at ca. 25� angle.
Paratypes. BRAZIL. Amapa: Rio Oiapoque, near
Cachoeira Tres Saltos, 2�12'N, 52�53'W, Irwin, Pires
& Westra 48137 (NY). FRENCH GUIANA. Without
locality, Moricand s.n. (G); Maroni-Camp Charveiu, Le-
m&e s.n. (P); road to St. Elie, CD-21, km 15.7, 5000'N,
53�10'W, Hahn 3696 (US); road to Kaw, km 34, 340
m, Billiet & Jadin 4593 (BR); Regina-St. Georges D.Z.
5-km 43-Ba River basin, Cremers 1991 (CAY); Rte.
RN 2, p.k. 53, Crique Boulanger, Billiet & Jadin 4464
(BR); Saiil, vic. Eaux Claires, 230 m, Croat 74174,
74195, 74235 (CAY, K, MO); 2 km S of Saiil, track
Limonade, 3�32'N, 53�12'W, 180-210 m, Ek & Mont-
foort 4 (CAY). SURINAM. Emmaketen, E slope of Gong-
grijptop, 900 m, Daniels & Jonker 932 (U); Emmaketen,
south track, 825 m, Jonker-Verhoef& Jonker 1061 (K,
NY, U); road to Petit Saut, Sauvain 654 (CAY). GUY-
ANA. Bartica-Potaro Road, 14-15 km, Sandwith 1154
(K); Akarabisi, a few meters from the Venezuelan border,
6"57'N, 60�22'W (MO, PORT); Upper Rupununi River,
near Dadanawa, 2�45'N, La Cruz 1521 (NY).
Philodendron placidum Schott, Bonplandia 7:
164. 1859. Philodendron guttiferum Kunth
var. placidum (Schott) Engler in Martius, Fl.
Bras. 3(2): 149. 1878. TYPE: French Guiana.
Cayenne: Martin s.n. (holotype, G-DC). Fig-
ures 7, 8.
Hemiepiphytic appressed climber spiraling around
the tree trunk several times below ca. 5 m, where
it branches and spreads before flowering. Internodes
3-5 cm long (to 16 cm on younger stems), 4-6
mm diam., matte, dark green, becoming gray, sharp-
ly flattened on one side, drying pale yellow-brown
with close, slender ridges, smooth but obscurely and
densely granular-puberulent at 30 x. Petioles 6.5-
11 cm long, sheathed throughout, the sheath 9-15
mm wide, glossy, spreading, truncate to emarginate
at apex, drying reddish brown. Blades 12-31 cm
long, 5-12.7 cm wide, oblong-elliptic or rarely el-
liptic, markedly inequilateral (one side 1.5-2.7 cm
narrower), abruptly acuminate at apex, narrowly
and inequilaterally rounded at base, subcoriaceous,
glossy on both surfaces, moderately bicolorous, dry-
ing grayish above, yellowish brown beneath. Midrib
weakly sunken above, convex below, often drying
undulate. Primary lateral veins 7-10, weakly sunk-
en above, weakly raised below, drying paler than
surface, arising at ca. 30� angle on the narrow side,
at ca. 45� on the broader side, weakly arcuate to
the margin. Minor veins drying moderately distinct
below. Inflorescence 1 per axil. Peduncle 1-2 cm
long, drying 4-6 mm diam. Spathe 9.5-12.5 cm
long, barely constricted above the tube, the tube
pale green, the blade white, caudate-acuminate at
apex (the acumen to 2 cm long), with reddish brown
resin droplets on inner surface, becoming greenish
throughout after anthesis, with the upper 3 cm of
the spadix remaining open after anthesis and with
the post-anthesis spadix remaining exserted 1-2.5
cm, the entire spathe drying reddish brown after
anthesis. Spadix 9.5-11.5 cm long, the staminate
portion narrowly long-tapered, to 6 mm diam.
Philodendron placidum is apparently wide-
spread in French Guiana, has been collected near
the Surinam border at Crique Gregoire, and is to be
expected in Surinam. This species is abundant ev-
erywhere in the vicinity of Eaux Claires near Sail
in south-central French Guiana.
The species is recognized by its spirally climbing
growth habit, its fully sheathed petioles, blades glossy
on both surfaces, and by its stubby inflorescence
with the spadix remaining slightly exserted after
anthesis. It is very easily confused with P. rud-
geanum Schott, which differs in climbing directly
up the side of the tree, and in having blades that
are matte rather than glossy on the lower blade
surfaces, a slender spadix, and in generally flowering
ahead of P. placidum. It was rarely at anthesis
during mid-February, whereas many plants of P.
placidum were in flower.
Though there are a number of older collections
of this species from the Guianas, the name has long
been applied only to a Schott drawing (2413) and
the holotype in Geneva, which may not be borrowed.
However, careful studies of the drawings as well as
photographs of the type specimen strongly suggest
that it represents the material here described. Schott's
drawing of the spathe shows it to be subelliptic and
open at anthesis with the male portion of the spadix
somewhat protruding forward. While the inflores-
cence at anthesis has not been seen at Saiil, the
proportions of the respective spadix portions agree
with the Schott drawings.
Specimens seen. FRENCH GUIANA. Without locality:
without collector (G); Crique Gregoire, ORSTOM Hydro-
logical Station, Deward 15 (CAY); Saul, 3�37'N, 53�12'W,
200-400 m, Mori & Pipoly 15599 (CAY); Saiil, trail
between Mont Galbao trail and Crique Limonade Trail,
200 m, 3�37'N, 53012'W, Mori et al. 20827 (CAY);
Saiil, vic. Eaux Claires, 240 m, Croat 74136 (B, CAY,
F, K, MG, MO, NY, P, US, VEN), 74192 (CM, MO);
Saiil, Monts la Fumee, 3�37'N, 53�12'W, Mori & Boom
15331 (CAY); Saut Mapaou-Approuague River basin,
4�12'N, 52�18'W, Cremers 13026 (CAY, MO); Trois
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Volume 4, Number 3
1994
217
Croat & Grayum
Philodendron subg. Pteromischum
Figures 7-10. 7, 8. Philodendron placidum Schott, Croat 74136. -7. Habit, showing spiral growth up a tree.
-8. Close-up showing post-anthesis inflorescence with a portion of the spadix remaining exserted. 9, 10. Philodendron
rudgeanum Schott, Croat 74130. -9. Habit, showing plant growing straight up the side of the tree. -10. Close-
up showing short-pedunculate inflorescence at anthesis.


Novon
Figures 11, 12. Philodendron surinamense (Miquel) Engler, Croat 74189. -11. Habit. -12. Leaf blade showing
lack of prominent primary lateral veins.
Sauts-road between Zidok and Capitaine Roger, Lescure
554 (CAY); Saut Koumaou Soula, S of Tampoc, Cremers
4458 (CAY).
Philodendron rudgeanum Schott, Syn. Aroid.
78. 1856. Philodendron guttiferum Kunth var.
rudgeanum (Schott) A. Jonker & Jonker in
Pulle & Lanjouw, Fl. Suriname 1(2): 73. 1953.
TYPE: t. 33 in Rudge, P1. Guian. 1(4). 1805
(holotype). Figures 9, 10.
Pothos cannifolius Rudge [as "cannaefolia"], P1. Guian.
1(4): 23, t. 33. 1805., nom. illeg., non Dryander
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Volume 4, Number 3
1994
Croat & Grayum
Philodendron subg. Pteromischum
ex Sims (1802). Monstera cannifolia ["cannaefol-
ia"] Schott, Wiener Z. Kunst 127(4): 1028. 1830.
Philodendron cannifolium (Schott) Engler, Bot.
Jahrb. 26: 512. 1899, nom. illeg., nec (Dryander
ex Sims) G. Don (1839) non Martius ex Kunth
(1841). TYPE: t. 33 in Rudge, P1. Guian. 1(4),
1805 (holotype).
Loosely climbing hemiepiphyte, usually climbing
straight up the side of the trunk to ca. 4 m before
branching and flowering. Internodes 5-20 mm long,
5-7 mm diam., weakly glossy, olive-green, drying
yellow-brown to dark brown, irregularly and acutely
striate, smooth. Petioles 5-10 cm long, sheathed
throughout, the sheath spreading, to 1 cm wide,
semiglossy except + matte on the abaxial surface,
drying finely striate on abaxial surface. Blades mod-
erately inequilateral (one side ca. 1 cm narrower),
narrowly elliptic to oblong-elliptic, broadest at the
middle or slightly above the middle, 11-23 cm long,
4.3-9.7 cm wide, obtuse to rounded and abruptly
acuminate at apex, acute to cuneate and abruptly
ending at base, thinly coriaceous, moderately glossy
above, moderately paler and matte below. Midrib
narrowly sunken above, thicker than broad below,
drying weakly and obtusely raised below. Primary
lateral veins 8-12 pairs, arising at 55-650 angle,
obtusely sunken above, weakly pleated-raised below,
drying flat and obscure above, weakly raised below.
Minor veins moderately distinct below, sometimes
weakly undulate. Inflorescences one per axil. Pe-
duncle 1-2.2 cm long, 3 mm diam., mostly obscured
by the sheath. Spathe 8.5-10.5 cm long, barely
constricted above the tube, narrowly cuspidate-acu-
minate at apex, pale green and semiglossy on both
surfaces at anthesis, paler within, the tube 1.3-2
cm diam. Spadix 8.7-11 cm long, weakly exserted
forward at anthesis, with 1-3 cm of the male spadix
remaining exserted beyond the end of the spadix
after anthesis. Pistillate portion 3.7-4.3 cm long,
8-9 mm diam., slightly narrower than the sterile
staminate portion at anthesis, becoming broader soon
after anthesis. Staminate portion moderately stubby,
5.3 cm long, ca. 1 cm diam., obtuse at apex. Sterile
staminate portion barely discernible from the fertile
portion. Abundant in most areas of the forest on the
lower trunks of moderately large trees.
Philodendron rudgeanum ranges from Trinidad
and northeastern Venezuela through the Guianas to
northeastern Brazil (Amapi and Belem), then dis-
junctly to Bahia.
This species is distinguished from Philodendron
placidum by having the blades matte on the lower
surface and by its growth habit, which consists of a
non-spiralling stem. It is most easily confused with
P. placidum, which differs in having blades glossy
on the lower surfaces and by climbing spirally up
trees. In addition, Philodendron placidum flowers
later than P. rudgeanum, which was only rarely in
flower in mid-February when P. placidum was in
full flower.
Philodendron surinamense (Miquel) Engler in
Martius, Fl. Bras. 3(2): 133. 1878. Elopium
surinamense (Miquel) Schott, Oesterr. Bot. Zeit.
15: 35. 1865. Anthurium surinamense Mi-
quel, Natuurk. Verh. Holl. Maatsch. Haarlem,
ser. 2, 7: 211. 1851. TYPE: Suriname. Host-
mann & Kappler 683a (holotype, U; isotype,
S). Figures 11, 12.
Philodendron riedelianum Schott, Oesterr. Bot. Zeit. 9:
98. 1859. TYPE: Brazil. Bahia: Ilheus, Riedel 752
(holotype, LE 2 sheets).
Hemiepiphytic vine. Internodes terete to subte-
tragonous, 1.5-11 cm long, 5-7 mm diam., green,
soon turning light brown. Petioles 2.5-12 cm long,
sheathed throughout, the sheath erect-incurled, me-
dium green, weakly glossy, free-rounded and nar-
rowly rounded at apex, to 1.2 cm wide when ex-
panded. Blades oblong-elliptic, 12-34 cm long, 3-
10 cm wide, acuminate or sometimes cuspidate at
apex, acute to rounded at base, subcoriaceous, semi-
glossy, slightly bicolorous, drying gray-green above,
yellow-green below. Midrib deeply sunken above,
convex below. Primary lateral veins flat and barely
apparent above, flat and darker than surface below,
little or not at all more apparent than the minor
veins below. Inflorescence 1 per axil. Peduncle 3.5
cm long. Spathe green, 11-15 cm long, narrowly
acuminate at apex, deciduous promptly after an-
thesis. Spadix 7-9.5 cm long. Pistillate portion 3-
4.3 cm long, 8-10 mm diam.
Philodendron surinamense ranges from southern
Venezuela (Bolivar and Amazonas) and the Guianas
to Ecuador (Pastaza), Peru (Loreto), and Brazil
(Amapa, Roraima, Amazonas, Maranhao, and Ba-
hia).
The species is recognized by its lack of primary
lateral veins on the blade and its prompt loss of the
spathe after anthesis. It is not easily confused with
any other member of subgenus Pteromischum.
Acknowledgments. Synonymy of Philodendron
rudgeanum was based on an unpublished manu-
script by Michael II. Grayum, "A taxonomic revision
of Philodendron subgenus Pteromischum (Araceae)
for Pacific and Caribbean Tropical America." We
thank Scott Mori and Dan Nicolson for reviewing
the manuscript.
219