38 Graminaceae 
CC. Perennial; glumes equal or nearly so; lemmas without hyaline margin, in- 
rolled. PASPALUM (p. 38) 
BB. Sterile lemma awned; glumes spiny-hispid, making the spike-like racemes some- 
what bristly. ECHINOCHLOA (p. 38) 
AA. Spikelets in open panicles, or if in a spike-like panicle this not |-sided. 
D. Spikelets without an involucre of bristles, in an open panicle. 
PANICUM (p. 38) 
DD. Spikelets with an involucre of bristles, clustered in a single dense terminal spike- 
like panicle. CHAETOCHLOA (p. 39) 
SYNTHERISMA (Digitaria) FINGER-GRASS 
Annuals. Spikelets in 2 to several spike-like racemes which are digitate or approx- 
imate at the summit of the stem, solitary or in 2’s or 3’s, I|-flowered, sessile or short- 
pedicelled, lance-elliptic. Rachis narrow or winged. Glumes |—3-veined, the first 
sometimes obsolete. Sterile lemma 5-veined; fertile lemma leathery-indurated, papil- 
lose-striate, not inrolled, hyaline margined, enclosing palet. Palet of same texture as 
glume. (Gk. syn=-with, therismos—crop; hence crop-making.) W. E. (Panicum 
sanguinale. ) S. sanguinale Dulac. (Crab-grass) 
PASPALUM 
Perennial. Spikelets 1-flowered, not awned, on short pedicels, usually plano-con- 
vex, in 1——2 simple or double rows, forming |-sided spikes. Spikes solitary, or in 
pairs or panicles. Glumes 2, equal or nearly so. Lemma enclosing palet, roundish or 
ovate. Palet firm, nearly flat. Stamens 3. JRachis not jointed, flattish or filiform. 
(Gk. paspalos—millet.) E. P. distichum |. (Joint-grass) 
PANICUM PANIC-GRASS 
Annual or perennial. Spikelets in panicles, rarely in spikes, |—2-flowered, when 
2-flowered the lower | staminate only. Glumes 2, very unequal, the first minute, the 
second subequaling the sterile lemma. Fertile lemma firm, awnless, margin inrolled, veins 
obsolete; sterile lemma often enclosing a hyaline palet and a staminate flower. Fertile 
palet like the fertile lemma in texture and veining. Stamens 3. Stigmas plumose. (Latin 
name of the Italian millet.) 
A. Spikelets acute to acuminate; plants annual. 
B. Stems 1.5—2.5 dm. high, slender; spikelets 2.5 mm. re. Wee. 
P, barbipulvinatum Nash 
BB. Stems 3—6 dm. high, stout; spikelets 2.5 mm. long. E. 
P. capillare L. (Old-witch Grass) 
BBB. Stems 4—6 dm. high, stout, spikelets 3.5 mm. long. E. 
. P. hirticaulum Presl. (Rough Panic-grass) 
AA. Spikelets obtuse; plants perennial. 
C. Spikelets 1.5 mm. long; stem slender; ligule 2—5 mm. long. W.C. E. (P. 
dichotomum and P. pubescens of How: FI.) : 
P. occidentale Scribn. (Hairy Witch-grass) 
CC. Spikelets 3.2—3.3 mm. long; stems stout; ligule | mm. long. W.E. (P. 
scoparium of How. FI.) P. seribnerianum Nash 
ECHINOCHLOA 
Annual, coarse. Spikelets in racemes and these in panicles, 1|-flowered, some- 
times a staminate flower below the perfect terminal one, nearly sessile. Racemes stout, 
