100 GKAMINEAE (gKASS FAMILY) 



10. AXONOPUS Beauv. 



Spikeiets 1-flowered, compressed bi-convex, sessile, solitary in two rows on one 

 side of a flattened rhachis (which is naked in ours), placed with the back of the 

 fertile lemma turned from the rhachis, forming simple spikes ; first glume obso- 

 lete ; lemma and palea indurated but less so than usual in JPaspalum, margins 

 of the lemma inroUed. — Perennials with 2-several slender spikes digitate or 

 sub-digitate at the summit of the culm. (Name from A^uv, axis; and ttoiJs, 

 foot:) Anastrophus Schlecht. 



1. A. furciltus (Flugge) Hitchc, Tufted, soft, 3-10 dm. high, with long 

 creeping leafy stolons ; leaves obtuse ; racemes a pair at the summit of the culm^ 

 7-10 cm. long ; spikeiets acute, nearly glabrous, about 4 mm. long. (Paspalus 

 Flugge J P. EllioUii Wats.) — Low moist ground, Ya. to Fla. and Tex. 



11. PANICUM L. Panic Grass 



Spikeiets 1-flowered or rarely with a staminate flower below the terminal 

 perfect one, in panicles, rarely in racemes ; glumes very unequal, the first often 

 minute, the second subequal to the sterile lemma which often incloses a hyaline 

 palea and rarely a staminate flower ; fertile lemma and palea chartaceous-in- 

 durated, nerves obsolete, the margins of the lemma inroUed ; grain free within 

 the rigid firmly closed lemma and palea. — Annuals or perennials of various 

 habit. (An ancient Latin name of the Italian millet, Setaria italica, of uncer- 

 tain origin and meaning.) 



a. Annuals h. 



b. Spikeiets tuberculate 2. /*. verrucosuTn. 



&. Spikeiets smooth c. 



c. Plants glabrous 8. P. dichotomiftorum. 



c. Plants more or less hispid d. — Capillaria. 

 d. Panicle erect, spikeiets not over 8.5 mm. long e 

 6. Panicle more than half the length of the entire plant. 



Panicle diffuse ; spikeiets 2-2.5 mm. long- . . . . 8. P. capillars. 

 Panicle narrow ; spikeiets 3-3.5 mm. long . . . .5. P.Jlexile. 

 e. Panicle not over one third the length of the entire plant. 



Culms stout; blades about 1 cm. wide . ... 4. P. Oaitinfferi. 



Culms delicate ; blades not over 6 ram. wide . . . . 6. P. philadelpMcttm . 

 d. Panicle drooping ; spikeiets 5 mm. long . . 7. P. miliaceum. 



a. Perennials /. 



/. Spikeiets short- pediceled along one side of a rhachis forming spike- 

 like racemes ... 1. P^ hemitomum. 



f. Spikeiets in panicles g. 

 fir. Basal leaves similar to culm-leaves, not forming a winter ro- 

 sette J culms simple or sometimes producing panicles from the 

 ■upper nodes h. 

 h, Spikeiets long-pediceled. — VirgIta. 



Branches of panicle spreading . .... . . 11. P. virgatwm. 



Branches of panicle ascending. 

 Spikeiets 4.5 ram. long ; leaves crowded at base of culm . 9. P. amarum. 

 Spikeiets 6 mm. long ; leaves not crowded at base of culm 10. P. amaroidee. 

 h. Spikeiets short-pediceled along the main branches of the pan- 

 icle i. — Agrostoidia. 



i. Rootstocks present 16. P. anceps. 



i. Eootstocks absent ; plants compressed at the leafy base. 



Fruit stipitate ; spikeiets conspicuously secund . .14. P. stipiicdum. 



Fruit not stipitate ; spikeiets not conspicuously secund. 

 Spikeiets 2 mm. long, crowded ; a few long hairs on the 



pedicels IS. P. agroetoides. 



Spikeiets 2.5-3 mm. long ; no hairs on the pedicels. 

 Panicles few-flowered, branches spreading . 12, P. longifoUum, 



Panicles densely flowered, branches erect . . 15. P. condensitm, 



g. Basal leaves usually dlstinctlv different from the culm-leaves, 

 forming a winter rosette ; cuini.s simple In spring but usually 

 much branched later in the season ; secondary panicles smaller, 

 less exserted than the primary ^, — Dioh^toma. 

 J. Spikeiets 3 mm. or more long k. 

 k. Loaves linear-elongated, not over 5 mm, wide ; secondary pan- 

 icles at the base only. 



Spikeiets pointed ,' IT. P. depoupsratum 



Spikeiets blunt 18. P. perlongum^ 



