% Order 156.— GR AMINES. 781 



subequal, and about equaling the oblong, terete, deciduous, short-stiped 

 flower; lower pale coriaceous, involute, inclosing the caryopsis and tipped 

 with a simple, jointed awn; scales linear-oblong. — 2f Fls. in a slender 

 or spike-like panicle. 



§ Sheaths all leaf-bearing. Stipe of the flower nearly glabrous, very short No. 1 



§ Sheaths, at least tho upper, leafless. Stipe conspicuously bearded Nos. ^8 



1 O. rnelanocarpa Muhl. Culm erect, simple, leafy, 18 — 24'; panicle simple, 

 flexuous, few-flowered ; spikelets racemous, ovoid-lanceolate ; glumes acuminate, 

 mucronate, 5 — 6" in length, smooth; pales hairy, nearly black when ripe, tho 

 lower one tipped with an awn an inch in length ; fruit black. — Rocky hills, U. & 

 and Can., frequent Aug. (Piptatherum nigrum Torr.) 



2 O. asperifolia Mx. Culm nearly naked, purple at base, 10 — 20'; lvs. subrad- 

 ical, erect, rigid, pungent at the point, nearly as long as the stem, cauline ones few 

 and very short; spikelets in a racemous, simple, flexuous panicle, 2 to 4' long, 

 1 — 2 upon each branch ; glumes abruptly acuminate ; pales ivhite, the lovjer one 

 with a long, bent awn. — Woods, N. States N. to Subarctic Am. Leaves green 

 through the winter. Caryopsis white, about as large as rice, farinaceous. May. 

 (Uraclme Trin.) 



3 O. Canadensis Torr. Culms slender, 9 to 18' high, naked abovo; lower 

 sheaths bearing rigid, involute-filiform lvs. ; pan. 1 to 2' long, narrow, tho branches 

 mostly in pairs; gls. often purplish, 1 to 2" long; pales white, bearded with whit- 

 ish hail's, the awn short and deciduous or wanting. — Rocky woods, N. Eng., to tho 

 shores of L. Superior. May. (Stipa juncea *Mx., nee L. S. Canadensis Poir. 

 LTrachno Trim Milium pungens Torr.) 



15. PAS'PALUM L. (Gr. -iTao-rraXog, millet; from the resemblance 

 of the seeds.) Spikelets plano-convex, in unilateral spikes ; glumes 

 (apparently) 2, membranous, equal, ovate or orbicular, closely pressed 

 to the fertile flower ; stigmas plumous, colored ; caryopsis coated with 

 the smooth, coriaceous pales. (But theoretically, the lower glume is 

 obsolete and its place supplied by the empty pale of an abortive flower. 

 In -Nos. 19 and 20 the lower glume appears, under a lens, as a mere 

 rudiment.) — Spikes linear, the fls. in 2 or 4 rows; rachis not jointed: 

 pedicels articulated. 



§ Paspai.um. Spikelets suborbicular, obtuse, crowded. Spikes alternate. (*) 



* Spikes many (7 to 30), with the spikelets mostly 4-rowed Nos. 1, 2 



* Spikes few (1 to 3), mostly solitary, slender (1" wide), 2 or 3-rowed No. " 



* Spikes i'ew (2 to 6) — with the spikelets in 2 rows, near 2" wide Nos. 4, !> 



— with the spikelets in 3 rows, near 3" broad, (a) 



a Leaves very hairy. Culms decumbent No. 6 



a Leaves only ciliato on the margins Nos. 7, 8 



a Leaves very glabrous, margins scabrous Nos. 9, lo 



§ Digitaria. Spikelets ovate or lanceolate, acute. Spikes mostly digitate. (**) 



** Rachis leaf-like, broader than the 2 rows of spikelets beneath it Nos. 11, 12 



** llachis narrow, triquetrous or flat, with the spikelets close-appressed. (b) 

 b Glumes (glume and pale) about equal, as long as the flower, (c) 



C Spikelets lanceolate. Spikes in pairs or threes Nos. 13, 14 



C Spikelets ovate. Spikes 2 to 4 oftener in pairs Nos. 15 — 17 



b Glume scarce half as long as tho pale. Spikes 5 to 12, clustered.. . .Nos. 18, 19 

 ** Rachis filiform with the spikelets loose and subremote Nos. 20, 21 



1 P. virgatum L. Culms decumbent at base, glabrous, 18 to 30'; lvs. broad- 

 linear, rough-edged, 12 to 18' by 5 to 6''; sheaths glabrous, with a hairy throat; 

 spikes numerous (7 to 12); rachis straight (not flexuous), fiat, narrower than the 

 4-rowed, dense, orbicular, obtuse spikelets. — If Moist soils, S. States, common in 

 the low country. Jl. — -Oct. — A very smooth variety is the P. confertum Le Conte. 



j3. purpurasceks. Culm below, lvs. and sheaths dark purple. (P. purpu- 

 rascens Ell.) 



2 P. undulatum Poir. "Plant very glabrous; lvs. long and linear, tomewhat 

 carinate; margin scabrous, base ciliate, sheaths glabrous; spikes many; rachis 

 flat, glabrous, margins scabrous, narrower than tho 2 to 4-rowed sjrikelets ; lower 

 glume pubescent, tipper glume (palea) smooth, transversely plaited near tlie margins.)'' 

 Kunth. Ga. and Fla. A variety of No. G? (P. plicatum Mx.) 



