12. ROTTBŒ́LLIA, L. f. ([Pl. 16.])
Spikelets in pairs at each joint of a terete slender spike, awnless; one imperfect or rudimentary on a short and thick appressed pedicel; the other sessile and imbedded in an excavation of the joint of the rhachis, 1-flowered or rarely with a second staminate flower. Glumes 4, obtuse, the outer hard and cartilaginous, with a transverse depression next the base, the inner one boat-shaped and membranaceous, the 2 upper thin and delicate. Stamens 3. Styles 2.—Tall or coarse perennials, with rigid stems, and single cartilaginous spikes terminating the stem and axillary branches, chiefly subtropical. (Named for Prof. C. F. Rottboell, an excellent Danish botanist, who wrote much upon Gramineæ, Cyperaceæ, etc.)
1. R. rugòsa, Nutt. Culm flattish, 2–4° high; leaves linear; spikes 1–2´ long, the lateral ones on short clustered branches in the axils, often partly included in the sheaths of the leaves; sterile flower neutral; lower glume transversely rugose.—Low pine-barrens, from S. Del. (W. M. Canby) southward near the coast. Sept.–Oct.
13. ERIÁNTHUS, Michx. Woolly Beard-Grass. ([Pl. 14.])
Spikelets spiked, in pairs upon each joint of the slender rhachis, one sessile, the other pedicelled, both 1-flowered, alike. Glumes 4, the 2 lower nearly equal, one 4–5-nerved, the other many-nerved; the 2 upper hyaline, one empty, the upper awned from the tip. Stamens 3. Grain free.—Tall and stout reed-like perennials, with the spikes crowded in a panicle, and clothed with long silky hairs, especially in a tuft around the base of each spikelet (whence the name, from ἔριον, wool, and ἄνθος, flower).
1. E. saccharoìdes, Michx. ([Pl. 14], fig. 1, 2.) Culm (4–6° high) woolly-bearded at the joints; panicle contracted; the silky hairs longer than the spikelets, shorter than the awn; stamens 2. (E. alopecuroides, Ell.)—Wet pine-barrens, from N. J. and Ill. southward; rare. Sept., Oct.
2. E. brevibárbis, Michx. Culm (2–5° high), somewhat bearded at the upper joints; panicle rather open; silky hairs shorter than the spikelets.—Low grounds, Va., and southward.
14. ANDROPÒGON, Royen. Beard-Grass. ([Pl. 14.])
Spikelets in pairs upon each joint of the slender rhachis, spiked or racemed, one of them pedicelled and sterile (staminate, pistillate or neutral), often a mere vestige, the other sessile, 1-flowered and fertile; lower glume the larger, coriaceous and nerved, blunt, the second carinate and acute, the 2 upper hyaline, the flowering glume awned from the tip. Stamens 1–3. Grain free.—Coarse, mostly rigid perennials, mostly in sterile or sandy soil; with lateral or terminal spikes commonly clustered or digitate; the rhachis hairy or plumose-bearded, and often the sterile or staminate flowers also (whence the name, composed of ἀνήρ, man, and πώγων, beard).
[*] Spikes digitate, thickish, short-bearded, the sterile spikelet staminate; stamens 3.