54 MISSOURI BOTANICAL GARDEN. 



mostly regular, strong, usually close, sometimes having the 

 Y fork. Tertiaries strong, regular when subtending regu- 

 lar secondaries, otherwise very irregular, forming meshes 

 of medium size, definite, inclosing distinct, moderately 

 branching terminals, except in young leaves where curling, 

 vanishing terminals may be observed, as in glaucophylla * 



The meshes, therefore, sometimes irregular, angular, but 

 generally oblong, blocky. 



As a whole, the venation is zigzag, or broken, thickened 

 at junctions, uneven, exceptionally strong, and no part 

 early obliterated* A character noticeable in several other 

 species, notably in adenophylla and petiolaris, but specially 

 marked in this, is, secondaries arching upwards in parallel 

 lines, — Plate 2, fig. 10. 



8. cordata is a central, typical form, around which cluster 

 petiolaris, sericea, discolor, adenophylla, and more distantly, 

 Candida. 



11. S. sericea, Marsh. — Primaries strong, distant, 

 curved-ascending, forming often very regular roundish loops 

 throughout. Secondaries sometimes regular, otherwise 

 much broken, weak. Tertiaries not much developed; 

 when present, forming angular, polygonal, medium or 

 small meshes, within which the very delicate flowing 

 terminals are to be observed. Along midrib narrow, deep- 

 green lines, and just outside of these, comb-terminals are 

 to be seen, more or less developed. 



With the exception of primaries, the veining is weak. 

 In some forms it is not easy to distinguish from 8. cor- 

 data. Generally, however, the veining has less strength, 

 especially the tertiaries ; terminals are more delicate, more 

 profuse, straightening on the borders of large ribs, which 

 is not the case in cordata; looping is more regular. While 

 the veining is more irregular, it is in gentler or more grace- 

 ful lines. — Plate 2, fig. 11. 



Illustration from specimens furnished by Prof. L. H. 

 Bailey, of Ithaca, N. Y. Examined specimens also from 



vicinity of St. Louis. 



9 



