3d24 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM, 
BEGONIACEAE. 
A PECULIAR BEGONIA FROM SOUTHERN MEXICO. 
Begonia unifolia Rose, Rep. Mo. Bot. Gard. 15: 80. 1904. 
Prater LN X and Fievrr 15, 
Tubcrons-rooted; leaf single, lying elose upon the ground, sessile, nearly orbicular, 
10 to 80.em. broad, with mostly 10 to 12 radiate once or twice forked principal veins, 
deeply cordate with overlapping lobes, deltoidly dentate with unequal teeth and 
frequently shallowly and broadly crenate, like the scape loosely white-villous with 
soft collapsible hairs that are mostly confined to the veins beneath but are scattered 
over the upper surface, and turn brown in drying: scape 40 to 60 cm. high, emerging 
through the base of the sinus, usually solitary, at first simple and staminate, later 
Fig. 15.—Begonia wnifolia and its surroundings, 
with one or more pistillate branches above the middle which are subtended by sub- 
orbicular, deeply dentate often cuneate bracts sometimes 4 to 6 cm. in diameter: 
bractlets small, persistent, deeply cleft and lacerate: flowers nearly white, glabrous, 
few at the end of the scape and its branch or branches, on slender glabrous or some- 
what villous pedicels of about their own length; staminate flowers about 25 miami. in 
diameter with 2 suborbicular often fimbriate sepals and 2 elliptical or spatulate nar 
rower petals; stamens many, crowded, with globose-cuneate small anthers much 
shorter than the distinet filaments; pistillate flowers longer-stalked, with 5 eaducous 
rather narrow perianth segments searcely half as long as those of the staminate 
flowers; fruit 10 to 25mm. lone, 3-celled, with 3 wings, of which one is much broader 
than the others, truneate above, cuneate or on the shorter capsules rounded at) base; 
placentce 2-cleft, bearing seeds on both surfaces: styles 3, short, forked, with con- 
tintious loosely spiral papillate stigmas. 
