636 GRAjnNE^. (grass family.) 



11. TRIP SAC UM, L. Gama-Grass. Sesame-Grass. (PI. 14.) 



Spikelets monoecious, in jointed unilateral spike.s, staminate above and fertile 

 below. Staminate spikelets in pairs, sessile at each triangular joint of the 

 narrow rhacliis, both alike, 2-fiowered, longer than the joints ; glumes 4, cori- 

 aceous, the lower (outer) one nerved, the second boat-shaped, the upper with 

 the palets very thin and membranaceous, awnless ; anthers opening by 2 pores 

 at the apex. Pistillate spikelets 2-flowered (the lower flower neutral), single 

 and deeply imbedded in each oblong joint of the cartilaginous thickened rha- 

 chis, occupying a boat-shaped recess which is closed by the polished and carti- 

 laginous ovate outer glume, the inner glume much thinner and pointed, the 

 upper with the palets very thin and scarious, pointless. Styles united ; stig- 

 mas very long (purple), hispid. Grain ovoid, free. — Culms stout and tall, 

 solid, from very thick creeping rootstocks. Leaves broad and flat. Spikes ax- 

 illary and terminal, separating spontaneously into joints at maturity. (Name 

 from rpi fico, to rub, perhaps in allusion to the polished fertile spike.) 



1. T. dactyloides, L. Spikes (4 - 8' long) 2 - 3 together at the summit 

 (when their contiguous sides are more or less flattened), and also solitary from 

 some of the upper sheaths (when the fertile part is cylindrical) ; in var. mo- 

 nostAchyum, the terminal spike also solitary. — Moist soil, from Conn, to 

 Penn. and Fla., near the coast, and from 111. southward. Aug. — Culm 4-7° 

 high ; leaves like those of Indian Corn. This is one of our largest and most 

 remarkable Grasses ; sometimes used for fodder at the South. 



12. ROTTBCELLIA, L. f. (PI. 15.) 

 Spikelets in pairs at each joint of a terete slender spike, awnless ; one im- 

 perfect or rudimentary on a short and thick appressed pedicel ; the other ses- 

 sile 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 depre.ssion next the base, the inner one boat- 

 shaped and membranaceous, the 2 upper thin and delicate. Stamens 3. St3'les 

 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 

 Graminese, Cyperace«, etc.) 



1. R. rugosa, 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. Canhy) 

 southward near the coast. Sept. - Oct. 



13. ERIANTHUS, Michx. Woolly Beard-Grass. (PI. 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 ^piov, wool, and &v6os, flower). 



