Fam. 94. Melastomataceae Juss. Melastoma Family 



Trees, shrubs, herbs or rarely vines with simple opposite 3- to 7- or rarely 

 1 -nerved leaves and commonly showy cymose flowers; flowers perfect, regular, 

 mostly 4- or 5-merous; hypanthium variously shaped; sepals valvate and petals 

 convolute in bud; stamens twice as many as petals, often dimorphic; anthers open- 

 ing by pores at the apex, commonly with an appendage; ovary superior; fruit a 

 capsule; seeds usually numerous, variously shaped and adorned. 



A large tropical family of about 240 genera and 3,000 species. 



1. Rhexia L. Meadow Beauty. Deer-grass 



Erect herbaceous or suffrutescent perennials, with one to several simple or 

 branched stems arising from the bases of previous shoots, from a woody crown, 

 from horizontal-spreading roots or from tuberous roots, essentially glabrous to 

 densely glandular-pubescent throughout; stems becoming woody or spongy below 

 (when growing in water), subterete about the middle with 4 well-defined faces 

 (sides) whose edges are inconspicuously to prominently winged; faces of stem flat 

 to convex and essentially equal or with one pair of opposing faces flat to concave 

 and much narrower than the other pair of convex or rounded faces; leaves opposite, 

 sessile to petiolate, suborbicular-ovate to linear-lanceolate or narrowly elliptic- 

 linear, with one to several palmate veins and with the margins ciliate to serrulate 

 or serrate; flowers usually showy, solitary or borne in cymes; petals 4, distinct, 

 oblique, cuneate to suborbicular, fugacious, mostly rose-color to purple, sometimes 

 white or yellow; hypanthium more or less urceolate, glabrous to variously glandular- 

 pubescent, the lower portion somewhat ventricose and enclosing all or most of the 

 capsule, constricted or narrowed above to usually form a neck, sometimes expanded 

 above the neck; calyx lobes 4, erect to spreading or strongly recurved, deltoid to 

 lanceolate, obtuse to acuminate or rarely aristate; stamens 8, isomorphic; anthers 

 1 -celled at anthesis, basifixed, commonly with an appendage at base, yellow, smooth 

 to papillose, more or less lanceolate in outline, straight or curved to sigmoid, dehisc- 

 ing by a pore; ovary 4-celled; fruit a capsule; seeds strongly curved to cochleate, 

 variously adorned. 



A small genus of about a dozen species that are centered in southeastern United 

 States. 



1. Anthers straight, 1-3 mm. long, the pore nearly equaling the diameter of 

 the anther tip; neck of the hypanthium conspicuously constricted 

 at the base, abruptly expanded above (2) 



1 . Anthers curved, 4 mm. long or more, the pore only about one third the 



diameter of the anther tip; neck of the hypanthium not constricted 

 at the base, gradually (if at all) expanded above (3) 



2(1). Petals rose-color; stem glabrous; leaves ovate to oval or elliptic, less than 

 3 times as long as wide 1. R- petiolata. 



2. Petals yellow; stem hirsute; leaves typically linear-elliptic, more than 3 times 



as long as wide 2. R. lutea. 



3(1). Stems glabrous throughout; hypanthium typically densely short glandular- 

 hairy; seeds wedge-shaped 5. R. alifanus. 



3. Stems always more or less hairy especially at nodes; hypanthium not as above; 



seeds cochleate (4) 



4(3). One pair of opposing faces of the stem flat to concave and much narrower 

 than the other pair of convex or rounded faces; stem neither con- 

 spicuously winged nor spongy-thickened below; leaves usually petio- 

 late; petals or mature hypanthium (or both) glabrous; flowers 

 white, rose or purple 3. R. mariana var. mariana. 



1169 



