52 MISSOURI BOTANICAL GARDEN 



Group II. — Secondaries partly irregular. 



6. S. nigra, Marsh. — Primaries distant, straight, or 

 curved-ascending, forming acute loops in lower portion, 

 united at the border by a marginal line in upper ; prominent 

 as compared with the rest of the veining. Intervening 

 costals one to several, often extending; to marginal line. 

 Secondaries not readily distinguished from the tertiaries, 

 not close, nor generally regular. Tertiaries delicate, form- 

 ing very minute angular, irregular, definite reticulation. 

 Within each mesh a single very slightly branching stem 

 is seen. 



The venation of this leaf is uniformly even, smooth, 

 brilliant, clear, and surpasses all others in the minuteness 



of its reticulation. 



meshes become 



vacant, retaining, occasionally, simply a stellate point. 

 Plate 1, fig. 6. 



Illustration from specimen of vicinity. 



7. S, AMVGDALOIDES. Anders. — 



amvgdaloides, Anders. — The veining of this leaf 

 is best described by comparison with S. nigra, to which it 

 bears a very close resemblance. The primaries are closer, 

 having but one or two intervening costals. In the lower 

 half they extend quite to the margin, not forming loops. In 

 the upper half looping is present, gradually merging at the 

 tip into a marginal line. Secondaries stronger, standing 

 out clearly from the tertiaries, mostly regular, closer, 

 straight. Tertiaries, of equal caliber as in nigra, usually 

 form a very regular net-work, resulting in larger, squarish, 

 blocky meshes. At maturity there are visible 



man) 



points in the centers of meshes, — an almost exclusive 

 characteristic pertaining to this leaf. The veining, as in 

 nigra, is even, smooth, whitish, brilliant. — Plate 1, fig. 

 7. Stipule on PI. 2, fig. 25. 



Illustrations from specimen of vicinity. 

 8. S. adenophylla, Hook. — Primaries strong, some- 

 what distant, simple, or dividing, forming towards the apex 



7 



