GRASS FAMILY 



119 



4. Chaetochloa geniculata (Lam.) 



Millsp. & Chase. 



Perennial Foxtail. Fig. 249. 



Pauicuiii geniciilatum Lam. Encvcl. 4: 727. 1798. 

 Setaria gracilis H. B. K. Nov. Gen. & Sp. 1 : 109. 1816. 

 Panicum imberbe Poir. in Lam. Encycl. Suppl. 4: 272. 1816 

 Chaetochloa imbcrbis Scribn. U. S. Dept. Agr. Div. Agrost. Bull. 



4: i9. 1897. 

 Chaetochloa gracilis Scribn. & Merr. U. S. Dept. Agr. Div. 



Agrost. Bull. 21: 15. /. 4. 1900. 

 Chaetochloa geniculata Millsp. & Chase, Field Mus. Bot. 3: 37. 



1903. 



Perennial; culms erect, 60-150 cm. tall; blades 

 elongate, narrow, 2-4 mm. wide, flat or folded ; panicle 

 slender, linear, 8-10 cm. long, 4-8 mm. thick ; bristles 

 5-8, twice as long as spikelet, pale or tawny ; spike- 

 lets 2-2.5 mm. long; fruit undulate-rugose. The blades 

 are usually without hairs. 



Open ground, dry or moist soil, southern United States to 

 Argentina. June-Sept. Type locality: West Indies. 



Chaetochloa nigrirostris (Nees) Skeels, an African species 

 resembling C . lutcsccus but with brown bristles and dark tips to 

 the fruit, has been found on ballast near Portland, Oregon 

 (Albina and Linnton, Suksdorf) . 



Pennisetum villosum R. Br. is cultivated for ornament and has occasionally escaped from gardens. It is 



a perennial with culms 30-60 cm. tall, villous below the panicle, and dense soft feathery terminal spikes 



2-7 cm. long; spikelets surrounded by an involucre of several slender plumose bristles 2-3 cm. long, the 



cluster falling from the a.xis entire. Santa Barbara County {Eastwood, Chase), Ventura (Parish). 



11. CENCHRUS L. Sp. PI. 1049. 1753. 



Spikelets few in a cluster, surrounded and enclosed by a spiny bur made up of several 

 coalescing bristles (sterile branchlets), the bur globular, the peduncle short and thick, 

 articulate at base, the spines retrorsely barbed. Annual or sometimes perennial, low branch- 

 ing grasses, with flat blades and racemes of burs terminating the culms and branches, the 

 burs readily deciduous. [Ancient Greek name for some grass.] 



Species about 25 in the warmer parts of both hemispheres, but chiefly in America. Type species, Cenchrus 

 ccliiiiatits L. 



1. Cenchrus pauciflorus Benth. 

 Sand-bur, Btir-grass. Fig. 250. 



Cenchrus pauciflorus Benth. Bot. Voy. Sulph. 56. 1840. 



Cenchrus tribuloides of authors, not L., and Cenchrus caro- 

 linianus of authors, not Walt. 



Annual ; culms much branched at base, ascending or 

 spreading, flattened ; sheaths loose ; blades firm, flat or 

 folded ; burs about 8 mm. tliick, 6-12 in short exserted 

 racemes. 



Sandy soil and desiccated pools, rare; California (San Ber- 

 nardino, Gilroy, Stanford University), Oregon (The Willows, 

 Linnton). Common eastward and south to Central America. 

 luly-Sept. Type locality: Lower California. 



12. HOMALOCENCHRUS ^lieg. Act. Helv. Phys. Alath. 4: 307. 1760. 



[Leersi.^ Swartz, Prodr. Yeg. Ind. Occ. 21. 1788, not Hedw. 1782.] 

 Spikelets 1-flowered, strongly compressed laterally, articulate with the pedicel; glumes 

 wantmg, lemma chartaceous, broad, oblong, boat-shaped, usually 5-nerved, the lateral pair 

 of nerves close to the margins, these and the keel often hispid-ciliate, the intermediate 

 nerves sometimes faint ; palea as long as the lemma, much narrower, usuallv 3-nerved, the 

 keel usually hispid-ciliate, the lateral nerves close to the. margins, the marg'ins firmlv held 

 by the margins of the lemma; stamens 6 or fewer. Perennial grasses, usually with creeping 

 rhizomes, flat scabrous blades, and open panicles, the spikelets nearlv sessile along one 

 side of the branchlets. [Greek, like-Cenchrus.] 



Species 10, tropical America and temperate North America, one species also in Europe and Asia. Type 

 species, Phalans orysoides L. 



