JOURNAL OF THE ARNOLD ARBORETUM THE GENERA OF MYRTACEAE IN THE SOUTHEASTERN UINITED STATES1 KENNETH A. WILSON MYRTACEAE Jussieu (MYRTLE FAMILY) Shrubs or trees with simple, opposite or alternate, coriaceous, glandular-punctate, exstipulate leaves, often with a continuous intramarginal vein.Inflorescence cymose, racemose, or paniculate or the flowers solitary.Flowers complete, regular. 4-or 5-merous. Calyx 4-or 5-lobed, distinct, orundivided in the bud and splitting irregularly in anthesis, or falling off asa calyptra. Petals 4 or 5 (attached at the apex of the hypanthium) orwanting. Stamens numerous, free or united into 5 bundles, the versatileanthers with gland-tipped connectives. Style and stigma 1, the ovaryinferior, (1)2-5-locular, each locule with 2-many ovules. Fruit a 1-many-seeded berry or a many-seeded capsule. Embryo variously shaped. A family of about 80 genera and 3000 species, primarily of the tropics ofboth hemispheres. The glandular-punctate leaves, inferior ovary, andnumerous stamens usually are distinctive. Two subfamilies based primarilyon the nature of the fruit generally are recognized: the Leptospermoideae,centered in Australia, are characterized by dry, dehiscent fruits: theMyrtoideae (with the single tribe, Myrteae) have fleshy, indehiscentfruits and occur in the tropics of both Old and New Worlds. The latteris divided into three subtribes based on the structure of the embryo.Subtribe Myrciinae Berg (cotyledons foliaceous, twisted and folded; theradicle elongate) is represented in our area by (alyptranthes. SubtribeEugeniiae Berg (cotyledons fleshy, distinct, partly or completely fused, orconferruminate (closely adherent); the radicle very short) includes Eugeniaand Myrcianthes, as well as the large Old World genus Syzygium. Sub-tribe Pimentinae Berg (cotyledons very short: embryo spiral or curved:radicle elongate) is represented in our flora by Myrtus. Psidium, andRhodom rtus. 'Prepared for a biologically oriented generic flora of the southeastern United States,a joint project of the Arnold Arboretum and the Gray Herbarium made possiblethrough the support of George R. Cooley and the National Science Foundation, andunder the direction of Reed C. Rollins and Carroll E. Wood, Jr. The scheme followsthat outlined at the beginning of the series (Jour. Arnold Arb. 39: 296-346. 1958).Other published portions of these studies will be found in Jour. Arnold Arb. 40, 41.1959, 1960. I am grateful to Rogers McVaugh who generously offered many com-ments and suggestions in connection with this family. I am also indebted to LeonardJ. Brass, George R. Cooley, and Richard A. Howard for their aid in obtaining speci-mens and their hell) in various other ways.[ VOL. XLI270
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