14 POACEAE. 



racemes 2-5 cm. long, nearly 1 cm. in diameter, exclusive of the bristles, the 

 rachis pubescent: bristles 5-10 mm. long: spikelets ovoid, acute, 2-2.5 mm. 

 long, the flowering scale acute, striate, finely transverse-rugose. Low ham- 

 mocks, L. keys. [E. K.] (Ber., Bah., Cuba, Ant.) 



2. C. gracilis (H.B.K.) Scribn. & Merr. Stems erect, 3-7 dm. tall, slender: 

 blades involute-setaceous, 2 dm. long or less, 1-3 mm. wide: racemes 2-6 cm. 

 long, 3-5 mm. in diameter: bristles 5-8, very short, equalling or twice as long 

 as the spikelet: spikelets 2 mm. long, ovoid, acute, the flowering scale acute, 

 abruptly apiculate, transversely rugose. Hammocks and cultivated grounds, 

 L. keys. 



3. O. magna (Griseb.) Scribn. Stems stout, 1-4 m. tall, branching at the 

 base: leaf -sheaths glabrous, compressed; blades 3-6 dm. long, 1-3 cm. wide, 

 rough: panicle usually interrupted below, 1-3.5 dm. long, 2-5 cm. in diameter; 

 bristles 1-3, green, 8-11 mm. long: spikelets elliptic, acute, 2 mm. long. 

 Hammocks and sand-dunes, U. keys. [E. K.] (Ant.) 



4. C. macrospenna Scribn. & Merr. Stems 6-12 dm. tall: leaf -blades linear- 

 lanceolate, 1-3 dm. long: panicle 1-2.5 dm. long, 2-4 cm. in diameter, exclusive 

 of the bristles: bristles single, 1.5-3 cm. long, green: spikelets narrowly ovoid, 

 acute, 3 mm. long, the flowering scale acute, narrowly ovoid, finely transverse- 

 rugose. Hammocks and sand-dunes, U. keys. [E. K.] (Bah.) 



5. C. caudata (Lam.) Scribn. Stems 3-6 dm. tall: leaf -sheaths pubescent: 

 blades linear, 1-3 dm. long, 3-5 mm. wide, pubescent, filiform-attenuate at the 

 apex: panicle 5-15 cm. long, the rachis slender and flexuous, pilose: bristles 

 single, flexuous, 4-10 mm. long : spikelets ovoid, acute, the flowering scale ovoid, 

 acute, short-apiculate, transversely undulate-rugose below. Low hammocks and 

 cultivated grounds, Key West. (Cuba, Ant.) 



14. CENCHROPSIS Nash. Erect plants with long rootstocks and terminal 

 spicate inflorescence. Spikelets single, the involucre of 1 or 2 outer rows of 

 barbed bristles and 1 or 2 inner rows of barbed spines which are 2-4 times as 

 long as the bristles and about equalling the spikelet. Scales 4. 



1. C. myosuroides (H.B.K.) Nash. Stems 6-14 dm. tall: leaf -blades 1-3 dm. 

 long, 3-8 mm. wide: spikes 5-20 cm. long: involucres numerous: spikelets 

 about 5 mm. long. Pinelands and edges of hammocks, U. keys, L. keys. 

 [E. ~K.](Bah., Cuba, Ant.) 



15. CENCKRUS L. Diffuse plants with terminal spikes. Spikelets 2-6, 

 in an involucre of two thick hard valves. Scales 4, awnless. SAND-BUB. 

 SAND-SPUR. BUR-GRASS. COCKSPUR. 



Involucre awned at the base. 



Involucre with short, generally reflexed, spines at the glabrous base : spikelets 2 

 in an involucre. 1. c. carolinianus. 



Involucre with erect barbed bristles at the villous base : spike- 

 lets 3 or 4 in an involucre. 



Spikelets 4 in an involucre : spines on the involucre not 

 Dasal - 2. C. echinatus. 



bpikelets 3 in an involucre : spines on the involucre basal. 3. C. virldis. 

 Involucre naked at the base. 4. c. incertus. 



1. C. carolinianus L. Stems 2-6 dm. long, branching: leaf -blades 6-12 cm. 

 long, 4-8 mm. wide: spikes 3-6 cm. long: involucres 6-20, the spines 3-4 mm. 

 long: spikelets 6-7 mm. long, usually not exserted beyond the involucre. 

 Hammocks and pinelands, U. keys, L. keys, L. S. keys. [E. K.] (Bah., Cuba, 

 Ant.) 



2. C. echinatus L. Stems branched: blades l^t dm. long, 5-15 mm. wide: 

 spikes 4-12 cm. long: involucres 20-50, densely crowded, green to purplish, 

 villous at the base, the spines 3-4 mm. long: spikelets 6-7 mm. long, exserted 



