MORPHOLOGY OF THE FLORAL ORGANS 115 



Fournier described the genus Jouvea from pistillate specimens. 

 Staminate plants of the same species (/. straminca Fourn.) he re- 

 ferred to Brizopyrum. The staminate specimens of Jouvea pilosa 

 (Presl) Scribn. were first described under Brizopyrum. The stam- 

 inate plants of Bulbilis dactyloides were first described under Sesleria. 



145. Monoecious genera, in which the staminate and 

 pistillate flowers are borne in distinct and dissimilar por- 

 tions of the inflorescence, are not common. These include 

 Tripsacum, Olyra, Zizania, and a few related genera. In 

 Tripsacum the staminate flowers occupy the terminal 

 portion of the spikes. In Olyra and Zizania (Fig. 31) the 

 staminate flowers are in the lower part of a panicle. In a 

 very few genera, the staminate and pistillate inflores- 

 cences occupy different parts of the same plant. Zea and 

 Euchlsena belong to this group. The tassel of the corn is 

 the staminate inflorescence; the ear is the pistillate 

 inflorescence. Not a few grasses, as many Andropogonese, 

 produce unisexual spikelets that are interspersed with 

 perfect spikelets, usually in some definite relation, but all 

 in the same inflorescence (Fig. 16). 



146. The axis of inflorescence. — The usual form is 

 slender and cylindrical, but it may take on a variety of 

 other shapes. In the spike of Hordese, the axis is somewhat 

 zig-zag by the alternate insertion of the large spikelets at 

 the nodes. The internodes or joints are flattened or con- 

 cave toward the spikelet and convex on the opposite side. 

 In many Hordese the axis disarticulates at the nodes at 

 maturity. Such disarticulation often occurs also in other 

 groups, especially among the Andropogonese. The axis is 

 sometimes greatly thickened and the surface hollowed 

 out, the spikelets fitting into the cavities. Such is the 

 case in Tripsacum, Manisuris and several other genera of 

 these tribes, and also in Stenotaphrum (Fig. 28). In the 



