30 



GRAMIXEJE. 



Spikelets without any involucre of bristles or spines. 

 Bractlet (in ours) apparently 1 only, enclosing a perfect flower; spikelets in 

 1-sided racemes or spikes which" (in ours) are arranged in pairs, or (rarely) 



in panicles 2. Paspalum. 



Bractlets 2, the upper subtending a perfect flower, the lower empty or sub- 

 tending a staminate flower: spikelets sometimes in 1-sided racemes or 



spikes; these digitate or in panicles 3. Panicum. 



Spikelets subtended by an involucre consisting of from one to many bristles or 

 spines (sterile branches) which are sometimes grown together. 

 Spikelets deciduous; bristles persistent 4. CHzETOCHLOA. 



2. PASPALUM L. 



Inflorescence of few digitate, or many panicled, spikelike racemes. 

 Spikelets in 1 to 4 rows upon one side of a flattened, jointless rachis, 

 jointed upon their short pedicels, plano-convex, obtuse or acute, 

 awnless, 1-flowered; bracts apparently 2 to 3 owing to the presence of 

 an empty bractlet which resembles a bract in size and texture and 

 takes its place; lower bract often obsolete, when present minute 

 1-nerved, slender, and placed on the flat side of the spikelet; upper 

 much larger, few-nerved. Bractlet (in ours) apparently 1 only, 

 really 2; lower empty, membranaceous, resembling and nearly equal- 

 ing the upper bract and performing the function of the absent or 

 reduced lower bract, 3-nerved; flower- enclosing bractlet roundish or 

 ovate, coriaceous, rarely mucronate or with a few minute hairs at the 

 apex, large, convex, and partly enclosing the palea. Palea smaller 

 than its bractlet, roundish or ovate, coriaceous, flattish. Scales 2, 

 wedge-shaped or quadrate, emarginate. Stamens 3. Ovary oblong, 

 smooth; styles elongated. Achene enclosed by the indurated bractlet 

 and palea. (The ancient Greek name for Millet-grass.) 



1. P. distichum L. Knot-grass. Rootstock perennial, widely 

 creeping; stems 6 to 24 in. high; sheaths somewhat crowded, smooth 

 or hairy, bearded or ciliate at the throat; blades flat, sharp-pointed, 

 linear-lanceolate, 1£ to 3 in. long, 1 to 2 lines wide, sparingly hairy 

 above, glabrous below, somewhat glaucous; spikes 2 (rarely 3 or 4), 

 1 to 4 in. long, sub-erect, densely flowered, one sessile, the other 

 shortly pedicellate; rachis J to 1 line wide; spikelets H lines long, 

 ovate, acute; those in the middle of a row overlapping about \ their 

 length; bracts more or less pubescent. 



Somewhat resembling Bermuda-grass but readily distinguished by 

 its stouter habit and by usually bearing only 2 spikes to each inflo- 

 rescence; appearance much modified by habitat. A tropical and sub- 

 tropical species, now common in marshy places throughout the 

 State; probably introduced: Lower Sacramento, 1893, Jepson; in 

 water in a ditch near Agnews, Miss Cannon; Clear Lake; Arbuckle; 

 Crescent City; at Upper Lake, Lake Co., "it has completely taken 

 possession of the Tule lands in the last 7 years," Edmonds, 1897. 

 Apr. -Oct. Considered a very valuable pasture-grass for marsh-lands. 



3. PANICUM L. Panio-gkrass. 

 Leaves often hirsute or hispid with stiff hairs arising from tubercles 

 between the nerves. Panicle loose and spreading, or close and spike- 



