258 GRAMINE^E. Panicum. 



2. PANICUM, Linn. PANIC-GRASS. 



Panicle various, either loose and spreading or close and spike- like, sometimes with 

 the inflorescence crowded upon one side of a narrow rhachis. Spikelets without 

 involucre or bristles at base, 1 J- or 2-flowered, articulated with their pedicels. Glumes 

 two, herbaceous, the lower smaller, often minute and sometimes wanting, the upper 

 equalling the perfect floret. Lower floret staminate or neutral, often reduced to a 

 single (lower) palet resembling the upper glum 3 ; its upper palet, when present, very 

 thin and hyaline : upper floret coriaceous or cartilaginous, usually closed and mostly 

 flattened parallel with the glumes, awnless ; lower palet enclosing the upper. Scales 

 2, fleshy, truncate. Ovary smooth, oblong : stigmas usually purple and longer than 

 the styles. Grain compressed, plano-convex, inclosed in the hardened palets. 



A vast largely tropical genus, over 800 species being recorded, of which it is estimated that 

 some 500 are really distinct. The flora of California differs remarkably from that of the Atlantic 

 States in the small number of native Panicums, as, while 35 to 40 species are found on the eastern 

 coast, not more than four can be regarded as natives of the western. But few of the genus are 

 useful to man ; the common Millet, P. miliaceum, was formerly more cultivated than at present, 

 both for its seeds and as a forage crop. Some botanists arrange the species here enumerated in 

 three different genera, as indicated by the following sections. 



1. Spikelets in pairs, one sessile, the other pedicelled, crowded on one side of 

 simple flattened branches, which are digitately clustered at the top of the 

 culm: lower floret neutral, of a single palet. DIGITARIA. 



1. P. sanguinale, Linn. (CRAB-GRASS or FINGER-GRASS.) Culms 1 to 2 feet 

 long, usually spreading and creeping at base, then ascending or erect : leaves and 

 sheaths smooth or hairy : spikes four to six or more, 2 to 4 inches long ; spikelets 

 1 to 1 lines long : lower glume very minute, the upper glume half the length of 

 the floret. Torr. Fl. N. York, ii. 423, t. 146. Digitaria sanguinalis, Scop.; 

 Eeichenb. Icon. Fl. Germ. i. 68, t. 187. P. fimbriatum, Presl in Eel. Hrenk. i. 298. 



Introduced ; a common annual weed in most countries, appearing late in the season and by 

 means of the roots at the lower nodes taking such a firm hold of the soil as to be very difficult to 

 remove. The spikes, and sometimes more or less of the plant, are purple. This is undoubtedly 

 the plant collected by Haenke. In the Southern States it is much valued for both hay and pas- 

 turage. It makes a very light hay, but affords a much-esteemed pasturage in midsummer. 



P. GLABRUM, Linn., the Smooth Crab-grass, of Europe and Asia, is very common in the Atlan- 

 tic States and is likely to be found here as a weed. It may be distinguished by having its upper 

 glume as long as the floret, while the spikes are shorter, fewer, and less regularly digitate. 



2. Spikelets disposed in panicles, scattered, awnless. PANICUM proper. 

 * Panicle elongated, racemose : spikelets small, short-pedicelled. 



2. P. agrostoides, Spreng. Culm from a perennial root, erect, about 2 feet 

 high, more or less flattened : leaves long and with the sheaths smooth : panicle 

 pyramidal, 4 to 8 inches long, often one-sided and frequently purplish ; spikelets 

 crowded and one-sided upon the branches, about a line long, ovate, acute : lower 

 glume half the length of the neutral floret ; upper glume 5-nerved : perfect floret 

 shorter than the upper glume, smooth except a few minute hairs at the apex. Trin. 

 Spec. Gram, iii, t. 261 ; Torr. Fl. K York, ii. 429, t. 148. 



This, which is a common species in the Atlantic States, is given as a native from its occurrence 

 in the collection made by Dr. Pickering and labelled " Valley of the Sacramento." 



* Panicle diffuse and spreading. 

 i Spikelets pointed. 



3. P. capillare, Linn. (OLD- WITCH GRASS.) Culms often branching at base 

 and forming large tufts 1 to 2 feet high, from an annual root : sheaths, and usually 

 the leaves, very hairy : panicle half the length of the culm, very open, its long 



