•6 TRIANDIMA. DIGYNIA. 



valves coriaceous, broatl, with many awns; 

 awns rigid and divergent. Corolla 2 valved, 

 outer valve terminated by 2 or 3 awns. — Flow- 

 ers spiked, intermediate masculine; lateral, her- 

 maphrodite, sessile. 



Small grasses, allied to FJymuSy valves of the calix re- 

 markably rigid and truncate, deeply divided inio many 

 flat and long scabrous awns; valves of the corolla also si- 

 milarly divided and awned. 



Species. 1. ^£. *Hystnx. Spike squarrose, with very 

 long recurved and divergent awns: calix smooth, gene- 

 rally 4-parted to the base: segments mostly bifid, un- 

 equally i2-awned; spikelet about 4 flowered, the 2 mascu- 

 line or neuter pedicellate, and intermediate; dorsal valve 

 of the corolla terminated by about 2 or 3 unequal awns. 



Considerably allied to Elymiis. Culm 4 to 6 inches 

 high. Leaves scabrous, str ate, pungently acute, about 

 2 mches long. Spike 1 or 2 mches, sheathed at the base. 

 Rachis flexuose, compressed, narrow, articulations dis- 

 tinct. Spikelets alternate, about 4-flowered, lateral her- 

 maphrodite flowers 2, sessile; intermediate, pedicellate, 

 the lower masculine, the uppermost smaller, abortive. 

 CaliX as in ElymxiSy mostly 4-cleft to the base; segments 

 usually bifid, striate, divergent, terminating in very long" 

 unequal awns, exterior awn more than 2 inches, subulate, 

 and i ecurved at an obtuse angle, interior awn shorter and 

 more slender. Corolla, dorsal valve terminated by a long 

 awn arising from betwixt two slender and unequal setae; 

 inner valve somewhat ciUate, terminated also by 2 short 

 cap diary awns. 



On the arid plains of the Missouri. 



Of tliis genus there are 2 species in the South of Eu- 

 X'ope, one of them also conrimon to Barbary, and the other 

 to Candia, there are likewise 2 other species peculiar 

 to those two places. 



118. ELYMUS. L. (Lyme-grass. Wild Rye.) 

 Calices lateral, 2-valved, many-flowered, ag- 

 gregated by pairs, in the manner of a 4-leaved 

 invol>JCi*mn. Corolla 2-valved. 



Flowers in simple spikes, alternately imbricated around 

 a common axis; spikelets 2, 4, oi 6.flowered, by pans, or 

 more rarely by thi'ees in eucii mdeiuure of the axis; valves 

 of the calix or common inrolucrum, very narrow and ri- 



