GENERA OF GRASSES OF THE UNITED STATES. 281 



and on opposite sides at each joint of the thick, hard articulate lower 

 part of the same rachis, sunken in hollows in the joints, consisting of 

 one perfect floret and a sterile lemma ; first glume coriaceous, nearly 

 infolding the spikelet, fitting into and closing the hollow of the 

 rachis; second glume similar to the first but smaller, infolding the 

 remainder of the spikelet; sterile lemma, fertile lemma, and palea 

 very thin and hyaline, these progressively smaller. 



Robust perennial grasses, with usually broad flat blades and 

 monoecious terminal and axillary inflorescences of 1 to 3 spikes, the 

 pistillate part below, breaking up into bony, seedlike joints, the 

 staminate above on the same rachis, deciduous as a whole. Species 

 about seven, all American, extending from the middle United States 

 to northern South America ; three species in the United States. 



Type species : Coix dactyloides L. 



Tripsacum L., Syst. Nat., ed. 10, 2: 1261. 1759. Type the first of the two 

 species described, T. dactyloides, based on Coix dactyloides L., and T. hermaph- 

 roditum. The second species, based on " Cenchrus 2, Brown. Jam. 367," is 

 now referred to Anthephora. 



Dactylodes Zanoni-Monti ; Kuntze, Rev. Gen. PI. 2 : 772. 1891. Two species 

 are included, D. angulatum, based on Coix angulatus Mill., and D. fasciculatum, 

 based on Tripsacum fasciculatum Trin. Coix angulatus, which is the same as 

 Tripsacum dactyloides, is taken as the type. 



The common species in the United States is Tripsacum dactyloides 

 (PL XX; fig. 170), a robust perennial, 3 to 6 feet tall, with broad 

 blades, the terminal spikes mostly in threes, the axillary spikes mostly 

 solitary. This species, called gama grass, is found in moist places 

 from Connecticut to Texas and Florida. It is a good forage grass, 

 but is usually not abundant enough to be of much importance. A 

 second species, T. floridanum Porter, with narrow blades, is found in 

 southern Florida, and a third species, T. lemmoni Yasey, with pilose 

 lower sheaths, is found in Arizona. 



142. EUCHLAENA Schrad. 



Staminate spikelets as in Zea; pistillate spikelets single, on oppo- 

 site sides, sunken in cavities in the hardened joints of an obliquely 

 articulate rachis, the indurate first glume covering the cavity; sec- 

 ond glume membranaceous, the lemmas hyaline. Spikes infolded in 

 foliaceous bracts or husks, 2 to several of these together inclosed in 

 the leaf sheaths. 



The one species generally recognized is Euchlaena mexicana 

 Schrad., a tall annual with somewhat the aspect of corn (Zea mays), 

 a native of Mexico. 



Type species : Euchlaena mexicana Schrad. 



Euchlaena Schrad., Ind. Sem. Hort. Goettingen. 1832. Only one species 

 described. The specimen was collected by Dr. Miihlenfordt in Mexico. 



The genus is little known. Several species have been proposed, 

 but they are doubtfully distinct from Euchlaena mexicana. An un- 



