space-consuming prophylls of some grass inflorescences 
seem to have been reduced to small pulvini; these struc- 
tures were later specialized for use in spreading the pan- 
icle branches at maturation. Compression during early 
development may also cause the rachis-segments to arch 
away from the attachment points of the spikelets. This 
bending of the rachis-segment is especially apparent in 
the most primitive subtribe of the Andropogoneae, the 
Saccharinae. Here (Hrianthus coarctatus) the inflores- 
cence is a spreading panicle with hairy filiform rachis- 
segments bending away from paired spikelets (Plate 
LVI, fig. 1). Further compression and reduction is ap- 
parent in the subtribe Rottboellineae, where one can trace 
a graded series of types leading toward formation of the 
cupulate fruit case (Plate LVI, figs. 2, 8, 4), as was 
pointed out by Weatherwax (1935). In Hlyonurus trip- 
sacoides we find contraction to a spike, and proceeding 
to Manisurus spp. there is reduction to solitary spikelets. 
At this stage the rachis-segment becomes slightly thick- 
ened and depressed, and there is a tendency for pedicels 
to become adnate to it. For example, in Hackelochloa 
a shallow rachis-segment is made functionally deeper by 
the adnation of the pedicel from a staminate spikelet 
along the inner lateral edge of the rachis-segment. The 
spikelet is then appressed into the resulting cavity by its 
outer glume. In the specimens examined, Manisuris 
tuberculosa represented the closest approach to the struc- 
ture of T’ripsacum. M. tuberculosa has a more conspic- 
uous pulvinus in the axil of each pedicel and a thicker 
rachis-segment than does M. cylindrica, Although Man- 
isuris, of all the Andropogoneae, most closely resembles 
the American Maydeae, it differs from T'ripsacum by 
having: (1) Perfect flowered spikelets, rather than uni- 
sexual ones; (2) Sterile pedicels which are remnants of 
the pedicellate spikelets of a pair, instead of the complete 
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