108 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



LVOE. 11 



Stems not filiform, larger, the leaves spreading. 



Plants with leaves narrow-elongate to elongate-ovate. 



Margins of the teeth entire; underleaves subquadrate, distant to imbricate, the 



apical margins only faintly 2— 4-lobed. 1. B. bidens. 



Margins of the teeth more or less crenulate; underleaves with variously and 

 deeply incised, toothed, and lobed margins, mostly broader than the stem. 



2. B. phyllobola. 



Plants with leaves asymmetrically ovate. 

 Leaves with a vitta. 



Underleaves mostly broader than the stem, with variously and deeply incised, 



toothed, and lobed margins. 2. B. phi/Uobola. 



Underleaves not broader than the stem, the lateral margins undivided. 



Ventral margin of the leaf strongly convex, arcuate, the teeth broad, the 

 acroscopic tooth usually the larger; cells of the apical portion with 

 conspicuous trigones, often coalesced. 3. B. herminieri. 



Ventral margin of the leaf scarcely convex, the teeth equal or nearly so; 



trigones small, rarely conspicuous. 6. B. gracilis. 



Leaves without a vitta ; teeth short, the sinus broad, lunulate. 



Cells of the apical portion of the leaf (18)24-36 m, the trigones very large and 



rounded. 5. B. roraimensis. 



Cells of the apical portion of the leaf 18-24 fi, the trigones small, conspicuous, 



often coalesced. 4. B. cuneistipula. 



. Leaves predominantly 3-toothed, occasionally only faintly so, or rarely entire, (subg. 

 Tridentatae) 



B. Leaves with a conspicuous vitta (sect. 5, Vittatae). 



Plants with underleaves chlorophyllose throughout, subquadrate to ovate in outline, 

 the lateral and apical margins variously lobed, toothed, and incised. 



52. B. spruccana. 



Plants with underleaves hyaline at least in the upper part, more or less regularly 

 4-toothed, the lateral margins undivided, entire. 

 Cuticle of the leaves and underleaves abundantly minutely punctate ; teeth of the 

 leaves well developed, four to six cells long; underleaves hyaline throughout, 

 often 2-4-lobed above. 53. B. tayloriana. 



Cuticle of the leaves and underleaves smooth to verruculose ; teeth of the leaves 

 one or two cells long, often recurved, sometimes absent ; underleaves chloro- 

 phyllose in the lower part. 

 Underleaves distant, one-third to one-half divided into four slender, acute, 



often spreading teeth. 54. B. nitida. 



Underleaves often approximate to imbricate, broader than the stem, undivided, 

 emarginate or with two to four obtuse lobes or teeth (some underleaves 

 of a stem may have four acute teeth). 55. B. heterostipa. 



B. Leaves without a vitta (in rare instances there is a suggestion of one). 



C. Underleaves connate at the base with one or both leaves ; leaf -margins entire, 

 inconspicuously serrulate to strongly dentate (sect. 2, Cownatae). 

 Underleaves connate by a few cells (often one or two) with one leaf only (always 

 on the same side of the stem). 

 Underleaves chlorophyllose throughout. 



Underleaves entire or nearly so. . . 32. B. fendleri. 



Underleaves variously 3-toothed, the margins strongly serrate and spinose 



37. B. cubensis. 



Underleaves with a border of hyaline cells. 



Leaves conspicuously 3-toothed, the margins strongly serrate and spinose. 



36. B. armatistipula. 



Leaves conspicuously 3-toothed, the margins obscurely serrate 35. B. eggersiana. 

 Leaves inconspicuously 3-toothed to truncate- undulate, the margins serrate 



and spinose. 34. B. pycnophylla. 



Leaves mostly rounded-entire, the apical margins only serrate. 



33. B. schwaneclciana. 



Underleaves connate with a pair of leaves. 



Plants of medium size to large, 2-3.5 mm broad, usually long, green becoming 

 brownish, smaller plants light green to greenish-brown; leaves usually 



