322 SYSTEMATIC BOTANY. 



4. P. DICHOTOMUM (Forked Panic Grass). Culm slender, erect, or 

 somewhat decumbent, generally very branching, and somewhat dichotomous ; 

 leaves linear-lanceolate, flat ; radical ones usually much shorter and broader, 

 dark green, as also the sheaths, sometimes pale green, and more or less hairy ; 

 panicles compound, terminal and lateral, with spreading branches ; lateral 

 panicles often short and simple ; lower flower neutral, with a single palea. 

 In moist situations, 4'-2o' high. June-September. 



5. P. CRUS-GALLI (Barnyard Grass]. Culm stout, branching at base ; 

 leaves lanceolate, flat, rough on the margin, otherwise smooth, as also the 

 sheaths ; spikes alternate, compound, forming a dense panicle ; lower flower 

 neutral, with 2 paleas ; lower palea awned ; awn rough, usually long. In 

 rich, waste grounds. August-September. 



23. Setaria. Spikelets in compound, cylindrical spikes, furnished 

 with i or more bristles, resembling awns ; otherwise as in the Panicums 

 proper. 



S. GLAUCA (Bottle Grass}. Culm erect ; leaves lanceolate, rough, hairy 

 at base ; spike dense, cylindric, of a dull-yellowish color when mature ; bristles 

 in clusters of 6-10, much longer than the spikelets. Weed in waste places, 

 1-2 feet high. July-August. 



24. Andropogon. Spikelets in pairs at the joints of the rachis, 

 spicate or racemed, one of them pedicellate, barren, often rudimentary ; 

 the other with the lower flower neutral ; the upper perfect. Paleoe 

 thin and delicate ; lower one awned at the tip. Stamens 1-3. ^ 



A. FURCATUS (Broom Grass). Culms erect, branching, nearly smooth ; 

 leaves linear-lanceolate, nearly smooth ; radical ones very long ; spikes 

 straight, 3-6, hairy, digitate or clustered at the top of the culm, usually pur- 

 ple ; spikelets approximate, hairy, appressed ; sterile spikelets staminate, 

 awnless ; stamens 3. In dry soils, 4-6 feet high. September. 



25. Sorghum. Spikelets pedicellate, in clusters of 2-3, forming 

 an open panicle ; lateral ones barren ; middle spikelet fertile. Glumes 

 coriaceous ; 2 lower flowers neutral ; upper flower with 2 paleae, the 

 highest awned at the tip. 



S. VULGARE (Broom Corn}. Culm tall, erect, solid ; leaves lanceo- 

 late, pubescent at base ; panicle very large, diffuse ; branches long, slender, 

 whorled, at length drooping ; perfect spikelets with hairy, persistent glumes. 

 Extensively cultivated, 6-12 feet high. 



26. Zea. Flowers monoecious. Barren flowers in terminal, clus- 

 tered racemes. Spikelets 2-flowered ; glumes 2, obtuse, nearly equal ; 

 paleae obtuse, awnless. Fertile flowers lateral and axillary. Spikelets 

 2-flowered, I flower abortive. Glumes 2, obtuse. Palese awnless. 

 Style I, very long, filiform. Grains in 3-12, usually regular rows, com- 

 pressed. (I) 



