92 



GKAMINEAE (GRASS FAMILY) 



1. TRIPSACUM L. Gama Grass. Sesame Grass 



Spikelets unisexual, 

 tinuous rhacliis above ; 



46. T. dactyloifles. 



Part of spike x l^^. 

 9 Spikelet embedded x 1. 

 9 Spikelet freed xl. 

 J" Spikelet x 1. 



ixillary spikes solitary- 

 Vug. Fig. 46. 



the staminate spikelets in pairs at the joints of the con- 

 the pistillate spikelets solitary, embedded in each oblong 

 joint of the cartilaginous thickened articulate rhachis 

 below in the same inflorescence, which terminates the 

 culm or its branches ; glumes of the staminate spikelet 

 subcoriaceous, the first dorsally flattened, the second 

 boat-shaped ; the first lemma often empty, membrana- 

 ceous with a hyaline palea, like the second wliich 

 incloses a staminate flower ; first glume of pistillate 

 spikelet ovate, at length cartilaginous and closing the 

 recess in the rhachis, second boat-shaped, coriaceous ; 

 florets 2, the lemmas and paleas hyaline, the lower 

 sterile, the upper pistillate. — Tall stout perennials from 

 very thick creeping rootstocks, with broad flat leaves, 

 and terminal and axillary spikes separating spontane- 

 ously into joints at maturity. (Name from rpi^eiv, to 

 riib, perhaps in allusion to the polished spike.) 



1. T. dactyloides L. Culms 1-2.5 m. high ; leaves 

 3 dm. or more long, 1.5-3.5 cm. wide; spikes 2-3 

 togetlier at the summit, when their contiguous sides 

 are more or less flattened, or solitary and terete ; 



, — Moist soil, Ct. to Kan., s. to Fla. and Tex. July, 



2. ROTTBOELLIA L. f. 



Spikelets in pairs in the excavations at the nodes of a cylindrical articulated 

 axis ; one sessile and perfect, the other pediceled, sterile, with its pedicel adnate 

 to the rhachis ; glumes of the perfect spikelet awnless, the 

 first coriaceous and covering the excavation in the rhachis, 

 the second thinner, boat-shaped ; sterile lemma empty or 

 with a rudimentary flower, and, like the lemma and palea, 

 hyaline ; glumes of sterile spikelet membranaceous. — Peren- 

 nials with flat narrow leaves, and single cartilaginous spikes 

 which disarticulate at maturity, terminating the stem and 

 branches ; chiefly subtropical. (Named for Prof. C. F. Bott- 



boell, an excellent Danish botanist, who wrote 



much upon Gramineae, Cyperaceae, etc. ) 



1. R. nigbsa Nutt. Culms tufted, com- 

 pressed, 6-12 dm. high ; sheaths flattened ; 

 leaves 5-10 mm. wide ; spikes 2-7 cm. long., 

 the lateral ones on short clustered branches in 

 the axils, often partly included in inflated 

 sheaths ; first glume of fertile spikelet trans- 

 versely rugose. {Manisuris Ktze. ) — Low pine 

 barrens, Del. and southw., near the coast. 

 Aug., Sept. Fig. 47. 



2. R. cylindrica (Michx.) Torr. Culms 

 terete from a short rootstock ; leaves 2-3 mm. 

 wide ; spikes slender^ usually curved, 5-15 cm. long, terminating 

 the culm, on elongated axillary peduncles; sterile spikelet rudi- 

 mentary : first glume of fertile spikelet obscurely pitted longi- 

 tudinally. (Majiisiiris Ktze.) — Prairies, Mo. and southw. June-Aug. Fig. 48. 



47. K. rugosa. 

 Base of inflorescence 



Part of same wth fer- 

 tile and pediceled 

 sterile spikelet sep- 

 arated X '2. 



Fertile spikelet x 2. 



Its tlower removed 

 x2. 



Lemma x 2. 



Is. i; 



oviindrica 

 x2. 



3. ERIANTHUS Michx. Woolly Beard Grass 



Spikelets in pairs, one sessile, the other pediceled, along the articulate and 

 readily disjointing rhachis, both alike, perfect ; glumes sul)equa,l, firm-membra- 

 naceous, the first dorsally flattened, more or less bicarlnafo, the second keeled 

 above ; sterile lemma empty, hyaline, awnless ; fertile lemma with an awn 1-2 cm 



