BY K. BREAK WELL, 389 



There are three primary bundles in tlie midrib. The middle 

 primary bundle has sclerenchyma well developed, on both the 

 superior and inferior surfaces. The middle primary bundle is 

 not larger than the other two primary bundles of the midrib. 

 Each lateral primary bundle has sclerenchyma better developed 

 than in most of the other species. A characteristic feature of 

 this grass is the extreme development of the sclerenchyma on 

 the superior surface of the midrib, extending the greater part of 

 the distance between the primary bundles. Generally speaking, 

 the secondary and intermediate bundles of this species are more 

 crowded and more numerous than those of the other species. 



The epidermal cells on the inferior surface are very irregular 

 in size, some being exceptionally large. The cuticle is much 

 thicker than in A. ajfiiiis, A. sericeus, and A. intermedhis, and is 

 more developed under the midrib and at the leaf-edges. The 

 cells on the superior surface are mostly bulliform in character. 

 They differ, however, from the bulliform cells of the species pre- 

 viously cited, in being much wider, not fan-shaped, and protected 

 by a well developed cuticle. Stomata are very numerous on the 

 inferior surface, but are not as plentiful on the superior surface 

 as in A. ajjinis, A. intertnedius, and A. sericeus. Trichomes are 

 numerous. 



Andropogon refractus R.Br. (Plate xxxii.). 



In a transverse section of the widest portion of the leaf, there 

 may be seen nine primary bundles. The secondary bundles are 

 not so numerous as those cited in the other species, being only 

 twenty in number. The intermediate bundles are very numerous, 

 there being twenty-one of these. 



The midrib is very wide, embracing bodily three primary 

 bundles, and extending so that two other primary bundles border 

 it at the edges. The middle primary bundle has well developed 

 sclerenchyma on the inferior surface, somewhat wedge-shaped in 

 character, and projecting well beyond the level of the epidermis. 

 It also encircles the greater part of the phloem-tissue. On the 

 superior surface, it extends from the epidermis to the xylem- 

 tissue, and surrounds the latter throughout the greater part of 



