268 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Rachilla joint and first glume forming a swollen ringlike callus 
at the base of the spikelet ; inflorescence paniculate, 
31. Eriochloa (p. 298). 
Rachilla joint and first glume not forming a callus at the base 
of the spikelet; inflorescence racemose. 
Racemes racemose along the main axis; first glume present. 
32. Brachiaria (p. 299). 
Racemes aggregated at the summit of the culm; first glume 
wanting___--_____.---- 33. Axonopus (p. 299). 
Spikelets in 2’s or 3’s or solitary, placed with the back of the fruit 
turned toward the rachis or pedicellate in panicles, 
Fruit long-acuminate, scarcely indurate, both glumes wanting; 
spikelet sessile, solitary, the stiff racemes horizontal or 
reflexed at maturity_...-.-_____ 34. Reimarochloa (p. 302). 
Fruit not long-acuminate, indurate (if but slightly indurate both 
glumes present). 
First glume typically wanting; spikelets plano-convex, sub- 
sessile in spikelike racemes______ 35. Paspalum (p. 302). 
First glume present; spikelets usually in panicles, biconvex to 
globose. 
Glumes or lemmas or both awned or, if short-pointed only, 
the summit of the fertile palea not inclosed and the 
spikelets crowded in short racemes. 
Inflorescence of 1-sided racemes along a common axis; 
glumes 2-lobed (rarely entire), awned from between 
the lobes; fruit indurate, the palea inclosed at the 
summit___-------_----_- | 43. Oplismenus (p. 343). 
Inflorescence paniculate. 
Spikelets long-silky ; first glume minute, remote. 
46. Tricholaena (p. 346). 
Spikelets not silky, often scabrous or hispid. 
Spikelets with a long-pointed callus at the base. 
® 45. Chaetium (p. 346). 
Spikelet without a callus___.44. Echinochloa (p. 345). 
, Glumes and lemmas awnless (fruit pointed in Scutachne). 
Lower floret of the spikelet perfect, usually fruitful ; spike- 
lets small, turgid, obtuse___.____ 42. Isachne (p. 341). 
Lower floret staminate or neuter. 
Second glume and sterile lemma leathery-indurate; fruit 
mucronate _________-__- 41. Scutachne (p. 341). 
Second glume and sterile lemma membranaceous; fruit 
not mucronate. 
Inflorescence a cylindric or interrupted spikelike pani- 
cle; fruit either scarcely indurate, the palea not 
inclosed at the summit, or stipitate and the spike- 
lets with a saccate second glume; aquatics or sub- 
aquatics. 
Second glume inflated-saccate ; fruit stipitate. 
39. Sacciolepis (p. 839). 
Second glume not inflated-saccate; fruit scarcely 
indurate, open at the summit, not stipitate. 
40. Hymenachne (p. 340). 
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