100 GRAMINEAE (GRASS FAMILY) 



10. AXONOPUS Beauv. 



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

 side of a flattened rhacliis (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 Paspalum, margins 

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

 sub-digitate at the summit of the culm. (Name from a^wv^ axis; and ttoi/s, 

 foot.) Anastrophus Schlecht. 



1. A. furcatus (Fliigge) 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 ; spikelets acute, nearly glabrous, about 4 mm. long. {Paspalus 

 Fliigge ; P. Elliottii Wats.) — Low moist ground, Va. to Fla. and Tex. 



11. PANICUM L. Panic Grass 



Spikelets 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 inrolled ; 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 b. 



b. Spikelets tuberculate 2. P. verrucosum. 



b. Spikelets smooth c. 



c. Plants glabrous , 8. P. dichotomifiorum. 



C. Plants more or less hispid d. — Capillaeia. 

 d. Panicle erect, spikelets not over 3.5 mm. long e 

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



Panicle diffuse ; spikelets 2->2..o mm. long . . . . 3. P. capillare. 

 Panicle narrow : spikelets S-:?.. 5 mm. long . . . .5. P. flexile, 

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



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



Culms delicate ; blades not over 6 mm. wide . ... 6. P. philadelphicum 



d. Panicle drooping ; spikelets 5 mm. long 1. P. rniliaceum. 



a. Perennials /. 



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

 like racemes \. P. hemitomum. 



/. Spikelets in panicles g. , 



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

 sette ; culms simple or sometimes producing panicles from the 

 upper nodes h. 

 h. Spikelets long-pediceled. — Virgata. 



Branches of panicle spreading 11. P. virgatum. 



Branches of panicle ascending. 

 Spikelets 4..o mm. long ; leaves crowded at base of culm . 9. P. amarum. 

 Spikelets 6 mm. long ; leaves not crowded at base of culm 10. P. amaroides. 

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

 icle i. — .Vgrostoidia. 



i. Rootstocks present 16. P. anceps. 



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



Fruit stipitate ; spikelets conspicuously secund . . .14. P. stipitatum. 

 Fruit not stijntate ; si)ikelets not conspicuously secund. 

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



pedicels 13. P. agrosioideg. 



Spikelets 2. .5-3 mm. long ; no hairs on the pedicels. 



Panicles few -flowered, brandies spreading . . .12. P. loyigifolirtm. 

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



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



forming a winter rosette ; culms simple in spring but usually • 



much branched later in the season ; secondary panicles smaller, 

 less e.Ksertcd than the primary _;. — Diohotoma. 

 j. Spikelets % mm. or more long k. 

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

 icles at the base only. 



Spikelets pointed 17. P. depanperntum. 



Spikelets blunt, t t • • t • t . . IS. P. perlongum. 



