100 



GRAMINEAE (GRASS FAMILY) 



10. AXONOPUS Beauv. 



Spikeiets 1-flowered, compressed bi-convex, sessile, solitaiy in two rows on oue 

 ?ide 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 Paspalum, margm? 

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

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

 foot.) Anastrophus Schlecht. . „ .^ •, , . ^. .., , 



1. A. furcatus (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 

 Fluo-ge ; P. EllioUii Wats.) — Low moist ground, Va. to Fla. and Tex. 



11. pAnICUM L. Pakic 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 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 5. „ ^ 



b. Spikeiets tuberculate ........ .2. P. verrucosum. 



h, Spikeiets smooth c. t^ , ^ 



c. Plants glabrous 8. P. dtchotomzflorum 



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

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

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



Panicle ditfuse ; spikeiets 2-2.5 mm. long . . . . 8. P. capillare. 

 Panicle narrow ; spikeiets 3-3.5 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 ram. wide. ... 6. P.philade.lphicurn 



d. Panicle drooping ; spikeiets 5 mm. long 1. 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. 

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

 sette ; culms simple or sometimes producing panicles from the 

 upper nodes h. 

 1v, Spikeiets long-pediceled. — VikgIta. 



Branches of panicle spreading . . . « . . . 11. P. mrgatum. 

 Branches of panicle ascending. 

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

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

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

 icle i. — Agrostoidia. 



i. Rootstocks present 16. P. anceps. 



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



Fruit stipitate ; spikeiets conspicuously secund . . .14, P. stipitatum. 

 Fruit not stipitate ; spikeiets not conspicuously secund. 

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



pedicels 13. P. agrostoidek. 



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



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

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



g Basal leaves usually distinctlv different from the culm-leaves, 

 forming a winter rosette ; cuims simple in spring but usually 

 much branched later in the season ; secondary panicles smaller, 

 less exserted than the primary _;. — Dichotoma. 

 ,). Spikeiets 8 mm. or more long k. 

 h. Leaves Hnear-elongated, not over 5 mm. wide ; secondary pan- 

 icles at the base only, 



Spikeiets pointed 17. P. depauperatum 



Spikeiets blunt 18. P. perlongum- 



