92 



(<;KASS FAMILY) 



1. TRIPSACUM L. (JAMA G*A88. SI--.SVMK 



Spikelets unisexual, 

 tinuous rhachis above ; 



46. T. dactyloides. 



Part of spike x iy 2 . 

 9 Bptkelet embedded x 1. 

 9 S pikelet freed x 1. 

 cf Spikelet x 1. 



axillary spikes solitary 

 Aug. 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 which 

 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 rplpeiv, to 

 rub, perhaps in allusion to the polished spike.) 



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

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

 together 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. Jtott- 



boell, an excellent Danish botanist, who wrote 



much upon Gramineae, Cyperaceae, etc. ) 



1. R. rug6sa Nutt. Culms tufted, com- l " 1: - ni?r<.>a. 

 pressed, 6-12 dm. high ; sheaths flattened ; p.asc of iniloreseeiice 

 leaves 5-10 mm. wide; spikes 2-7 cm. ln</, x a . 



J Jj the lateral ones on short rlaxtrrrd branches in 



m /H ^ e ax ^ s -> ften partly included in inflated 



fjl sheaths ; first glume of fertile spikelet trans- 



" versely rugose. (Manisuris Ktze.) Low pine 



barrens, Del. and south w., near the coast. 

 Aug., Sept. FIG. 47. 



2. R. cylfndrica (Michx.) Torr. fv////s 

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



i:. cylindrica- wi( * e ; spikes slender, usually curved, f>-l "> an. Jong, terminating 

 X '2. the culm, on elongated axillary p<'<ium-i,-s; sterile spik. let rudi- 



mentary ; first glume of fertile spikelet obsnirrl;/ /lifted longi- 

 tudinally. (Manisuris Ktze.) Prairies, Mo. and southw. June-Aim. Fn;. -IS. 



3. ERIANTHUS Michx. WOOLLY BEAUD GRASS 



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

 readily disjointing rhachis. both alike, perfect; glumes Sttbequal, tirm-membra- 

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

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



Part <>f same with fer- 

 tile and pedieeled 

 sterile spikch-t sep- 

 a rat i-d x _'. 



Fertile .--pikelet x _'. 



Its Mower removed 

 x2. 



I.emma X 2. 



48. 



