MORPHOLOGY OF THE FLORAL ORGANS 115 
Fournier described the genus Jouvea from pistillate specimens. 
Staminate plants of the same species (J. straminea Fourn.) he re- 
ferred to Brizopyrum. The staminate specimens of Jowvea pilosa 
(Presl) Scribn. were first described under Brizopyrum. The stam- 
inate plants of Bulbilis dactyloides were first described under Sesleria. 
145. Moneecious 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 
Euchlena 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 Andropogonee, 
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 Horde, 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 Hordeze the axis disarticulates at the nodes at 
maturity. Such disarticulation often occurs also in other 
groups, especially among the Andropogonex. 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 
