572 GRAMINEA:. (GRASS FAMILY.) 



48. AMPHICABPUM, Kunth. 



Perennial flat-leaved grasses, with the spikelets nearly as in Panicum, but of 

 two kinds ; one perfect, but rarely fruitful, disposed in a simple terminal panicle 

 or raceme ; the other larger, pistillate or perfect, and borne at the summit of long 

 runner-like radical peduncles. Lower glume minute or wanting. 



1. A. Purshii, Kunth. Culms tufted, erect from fibrous roots, naked 

 above ; leaves lanceolate, rather thin, clothed, like the sheaths, with spreading 

 rigid hairs ; upper flowers in a strict panicle ; those at base of the culm perfect ; 

 grain ovoid or oblong, terete. (Milium amphicarpon, Pursh.) Low sandy pine 

 barrens, Georgia, and northward. Sept. Culms 1- 3 high. Glumes of the 

 upper flowers 5-ncrved, of the lower one white, many-nerved. 



2. A. Floridanum, n. sp. Culms subterraneous, diffusely creeping; 

 flowering branches erect ( 1 - 3 high), branching ; leaves linear-lanceolate, rigid, 

 smooth ; sheaths fringed on the margins ; upper flower abortive, panicled or 

 racemed, oblong (3" long), acute ; glumes 5-nerved ; anthers of the radical flow- 

 ers imperfect ; grain compressed-globose, pointed. Banks of the Apalachicola 

 River, Florida. Sept. and Oct. Plant pale green. Paleae of the radical flow- 

 ers crastaceous at maturity. 



49. PANICUM, L. PANIC-GRASS. 



Inflorescence spiked, racemose or panicled. Spikelets 2-flowered, naked (no 

 involucre). Glumes 2, herbaceous ; the upper one usually as long as the flow- 

 ers, the lower smaller, often minute, or occasionally wanting. Lower flower 

 staminate or neutral, of 1 - 2 palese ; the upper palea, when present, small and 

 hyaline, the lower herbaceous and resembling the upper glume. Upper flower 

 perfect, coriaceous, awnless, enclosing the free grain. Stamens 3. 

 1. DIGITARIA. Inflorescence spiked: spikelets 2-3 together, imbricated on 



one side of a flliform rachis : lower flower of one palea, and neutral : glumes 



shorter than the flowers : annuals. 



1. P. sanguinale, L. (CRAB-GRASS.) Culms ascending from a diffusely 

 creeping base ; leaves thin, spreading, the lower part, like the sheaths, hairy ; 

 spikes 5 - 10, spreading ; spikelets oblong, pointed ; glumes hairy on the mar- 

 gins, the upper half as long as the flowers, the lower minute, or in var. VILLOSUM 

 (Digitaria villosa, Ett:, a smaller and more hairy form) wanting. Cultivated 

 grounds and waste places everywhere. May - Oct., 



2. P. filiforme, L. Culms erect, sparingly branched (2 - 3 high) ; leaves 

 linear, erect, and, like the sheaths, hairy ; spikes 2-5, alternate, erect, filiform ; 

 spikelets oblong, acute, scattered ; upper glume half as long as the acute black- 



.ish palea, the lower wanting. Dry sandy soil, common. Aug. and Sept. 

 2. PANICUM PROPER. Glumes 2, unequal, awnless : spikelets in panicles 



or racemes. 



* Spikelets crowded in simple or panicled racemes. 

 +- Sterile flower of one palea, neutral. 



3. P. tenuiCUlmum, Meyer. Culm filiform, erect, simple ; leaves chiefly 

 radical, linear (2" wide) ; racemes 8 - 12, remote, 3 - 6-flowered, forming a long 



