POACEAE 85 
branches erect to spreading : spikelets, exclusive of the awns, 2.5-3 mm. long, the longer 
awns 6-8 mm. long. 
In low woods and swamps, Georgia to Texas. Also in tropical America. Summer and fall. 
31. PANICUM L. 
Annual or perennial grasses, varying much in habit, with elongated or flat and broad 
leaf-blades, and the spikelets in open or contracted panicles. Spikelets 1-2-flowered, lance- 
olate, oblong, ovate to obovate or globose, obtuse to acute or acuminate. Scales 4, the 
3 outer membranous, the first and second empty, the first usually much shorter than the 
spikelet, sometimes minute, the third one empty or enclosing a shorter hyaline palet and 
often alsoa staminate flower ; fourth scale shorter and usually more obtuse than the others, 
chartaceous, glabrous and shining, at length indurated, enclosing a palet of similar texture 
and a perfect flower. Stamens 3. Styles distinct. Stigmas plumose. 
Herbs, varying in habit. 
Spikelets disposed singly or in pairs in one-sided racemes, the pedicels short. I. PASPALOIDEA. 
Spikelets arranged in panicles but not disposed in one-sided racemes, the 
pedicels short or long. 
Basal leaf-blades long and narrow, similar to those of the stem: no rosu- 
late tufts of leaves in the fall: spikelets lanceolate to ovate, usually 
the former, acute to acuminate, rarely obtuse. 
Spikelets manifestly tuberculate. II. VERRUCOSA. 
Spikelets not tuberculate. 
Basal leaf-sheaths round or but little flattened, not keeled. 
Fourth scale smooth. 
Annuals or perennials, if the latter no rootstocks or stolons. III. CAPILLARIA. 
Perennial by long rootstocks or stolons. 
Rootstocks and stolons naked or with a few large scales : 
sandbinders. IV. HALOPHILA. 
Rootstocks, at least when young, and stolons covered with 
numerous small broad acute scales. V. VIRGATA. 
Fourth scale transversely rugose. VI. MAXIMA. 
Basal leaf-sheaths much crt ahire broad, keeled, often equitant. VII. AGROSTOIDEA. 
Basal leaf-blades commonly unlike those of the stem, ovate to ovate- 
lanceolate: perennial by rosulate tufts which form in the fall at the 
base of the stems: spikelets elliptic to spherical, usually obtuse, some- 
times acute, never acuminate. s VIII. DICHOTOMA. 
Much branched shrubs, with broad leaf-blades: spikelets large and turgid, the 
outer scales woolly-tipped. IX. LATIFOLIA. 
I. PASPALOIDEA. 
Fourth scale of the spikelet smooth. 
Spikelets not ciliate with long hairs, the first scale 14 as long as the spike- 
let or less, excepting in no. 2. 
Terrestrial grasses. - 
Stems prostrate: leaf-blades short, ovate-lanceolate, spreading. 1. P. prostratum. 
Stems erect: leaf-blades long and relatively narrow, 
Spikelets obtuse, turgid, the first scale very large, rounded at the 
apex, more than 1; as long as the spikelet. 2. P. obtusum. 
Spikelets acute, the first scale small, acute at the apex, less than 
15 as long as the spikelet. . P. molle. 
Aquatic grasses. 
Spikeléts singly disposed, about 3 mm. long, the first scale rounded 
or truncate at the He 
Spikelets in pairs, about 2 mm. long, the first scale acute at the sum- 
e 
4. P. paspaloides. 
Qr 
. P. digitarioides. 
. P. ciliatissimum. 
Iz] 
mit. 
Spikelets ciliate with numerous very ond EN the first'scale narrow and 
acuminate, nearly as long as the spikelet. 
Fourth scale transversely rugose: usually the outer scales of some or all of 
the spikelets with anastomosing veinlets. : 
sri oo of the panicle terminated by a spikelet, no extension beyond 
them. 
Spikelets 2.5-3 mm. long, broadly obovoid, obtuse or acutish, anasto- 
mosing veinlets numerous and prominent. : 1 7. P. fuscum. 
Spikelets 4-6 mm. long, acute or acuminate. oval, anastomosing vein- 
lets few and faint. 
Spikelets about 4 mm. long, the first scale less Mr their length. 8. P. fasciculatum. 
Spikelets 5-6 mm. long, the first scale more than 4 their Mag lu 9. P. Texanum. 
Branches of the panicle extending beyond thespikelets in an awn-like pro- 
jection. : : : 
First scale of the spikelet 1-nerved, or sometimes with a faint lateral 
. nerve on each side. 
First scale of the spikelet 5-nerved. : 
Spikelets 2.5 mm. long : leaf-blades usually short. 1 1. P. ramisetum, 
Spikelets 3.5 mm. long : leaf-blades usually elongated. 12. P. Reverchonii. 
10. P. Chapmanii. 
II. VERRUCOSA. 
Spikelets about 2 mm. long, the tubercles not hair-bearing. 13. P. verrucosum, 
Spikelets about 3 mm. long, each tubercle bearing a short stout hair. 14. P. brachyanthum. 
