572 GRAMINK^E. (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 l°-3°high. Glumes of the 

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



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

 flowering branches erect (l°-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 crustaceous 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 filiform 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. villosdm 

 (Digitaria villosa, Ell., a smaller and more hairy form) wanting. — Cultivated 

 grounds and waste places even-where. 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 ; 

 Bpikelets 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, aicnless : spikelets in panicles 



or racemes. 



* Spikelets crowded in simple or panicled racemes. 



■*- Sterile flower of one palea, neutral. 



8. P. tenuiculmum, Meyer. Culm filiform, erect, simple ; leaves chiefly 



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



