MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



[VOL. 11 



Underleaves never deeply 4-lobed; ventral auricles of the leaves 

 large or small. 



Underleaves usually large, more or less quadrate, the margin 

 often angled and incised, the auricles more or less toothed; 

 cells 18 the cavities stellate ; trigones very large, knot- 

 like; leaflets of the flagelliform branches large. 42. B. falcata. 

 Underleaves large, usually entire, the apex undulate or with an 

 occasional tooth ; cell cavities angular-rounded ; trigones 

 large to medium size. 

 Leaves not conspicuously narrowed to the apex; ventral ap- 

 pendages rare or absent ; teeth broad, the cells mostly 

 20 n, with conspicuous trigones. 43. B. hookeri. 



Leaves narrowed to the apex; teeth sharp, pointed. 



Leaves spreading, the cells 18-20 n; leaflets of the flagelli- 

 form branches scalelike. 46. B. liebmanniana. 

 Leaves more or less falcate, the cells large, 24—36/*; leaf- 

 lets of the flagelliform branches large. 44. B. robusta. 

 E. Auricles of the leaves, if conspicuous, never appendiculate ; underleaves at- 

 tached in a straight or rarely a curved line; line of the leaf insertion 

 curved to hook-form. (sect. 1, Grandistipulae) . 

 Underleaves in part of hyaline cells which often form a conspicuous border. 



Leaf margins serrate throughout; leaves mostly 3-toothed. 10. B. serrata. 



Leaf margins not serrate. 



Leaf cells thin-walled; trigones absent or minute; underleaves hyaline 



except for a small internal area at the base. 7. B. affinis. 



Leaf cells thin- walled; trigones small to conspicuous, often with bulging 

 sides, the cell lumina angular-rounded. 

 Underleaves longer than broad, one-third to three-fourths hyaline, the 

 apex variously incised or spinose, the lateral margins scarcely 

 bulging; leaves elongate, the teeth usually coarse, the cells mostly 

 36 ju. f forms of] 8. B. pallide-virens. 



Underleaves subquadrate-rounded, the hyaline border continuous to the 

 base. 



Hyaline cells thin-walled, without trigones; ehlorophyllose cells of 



the interior with conspicuous trigones. 9. B. stolonifera. 



Cell walls and trigones of the hyaline and ehlorophyllose areas 

 similar. 



Hyaline border narrow, of one to four rows of cells; teeth of the 

 leaves usually ending in a 1-celled point; cuticle coarsely 

 verruculose. 11. B. chilensis. 



Hyaline border variable, narrow or including half the underleaf, 

 or absent; teeth of the leaves usually ending in a 2-celled 

 point; cuticle faintly verruculose. 12. B. taleana. 



Underleaves ehlorophyllose throughout (rarely with a few scattered hyaline 

 cells on the margin). 

 Underleaves variously toothed or deeply lobed to incised, spinose or dentate 

 in the apical portion and often on the lateral margins. 

 Underleaves spinose-dentate and ciliate to the base. 13. B. denticulate. 



Underleaves coarsely toothed, broad-lobed, or irregularly incised, nevef 

 ciliate. 



Underleaves conspicuously 4-lobed or variously incised and with a few 

 spinose teeth in the upper part. 

 Underleaves twice as long as broad, with four long, rounded lobes. 



27. B. elongata. 



Underleaves approximately as broad as long. 



Plants very robust, green or brown; leaves with large teeth; 

 underleaves very large, subquadrate and strongly cordate. 

 Plants olive-green to brown; leaf cells with very large triradiate 

 trigones; margins of the underleaves never hyaline. 



28. B. crassidentata. 



