GKAMINEAE (GRASS FAMILY) 91 



64. Catabrosa. Spikelets 2-flowered. 



= = Lemmas 5-inany-nerved (nerves often obscure in Sriza). 



a. Spikelets nearly sessile in dense 1-sided clusters at the end of the few panicle-branches. 

 TO. Dactylis. Spikelets flattened ; glumes and lemmas keeled, the keels hispid-ciliate. 



a a. Spikelets not in dense 1-sided clusters. 

 b. Spikelets as broad as long, somewhat heart-shaped. 



69. Briza. Florets crowded in the spikelets, almost horizontal ; lemmas boat-shaped or ventricose. 

 b b. Spikelets much longer than broad, not heart-shaped. 

 c. Lemmas keeled. 



71. Poa. Base of florets often cobwebby. 



c c. Lemmas convex or keeled only at the summit. 



d. Uppermost lemmas shaped like the lower, fertile or sterile. 



e. Nerves of lemma prominent, parallel. 



73. Glyceria. Spikelets compressed-cylindrical or little flattened ; lemmas scarious at summit. 



e e. Nerves of lemma not prominent. 

 /. Lemmas obtuse, awnless. 



74. Puccinellia. Glume* much shorter than the lowest lemma ; callus not hairy ; nerves not 



excurrent. 



72. Scholochloa. Glumes nearly as long as lowest lemma ; callus hairy ; one or more nerves of 



lemma excurrent. 



//. Lemmas acute, often awned. 



75. Festuca. Lemmas entire, often awned from the apex. 



76. Bromus. Lemmas 2-toothed, usually awned just below the apex ; grain adherent to the 



palea, pubescent at the summit. 



65. Melica. Lemmas awned just below the apex, grain free, glabrous. 



d d. Uppermost lemmas broad or cucullate, convolute, forming a club-shaped mass. 

 C5. Melica. Lemmas subcoriaceous with a scarious margin, obtuse. 



Tribe X. H6RDEAE. Spikelets (1-several-flowered, with uppermost floret imperfect) sessile on 

 opposite sides of a zigzag jointed channeled rhachis, forming a spike; glumes sometimes abor- 

 tive or wanting, often placed together in front of the spikelet ; leaf-blades bearing at base a 

 more or less well-marked pair of auriculate appendages. 



* Spikelets solitary at each joint of the rhachis. 

 -*- Spikelets 1-flowered, falling attached to joints of the disarticulating rhachis. 



78. Lepturus. Spikelets awnless; low branching annuals. 



-i- +- Spikelets 2-many-flowered. 



77. Lolium. Spikelets placed with one edge to the rhachis. 



79. Agropyron. Spikelets placed with the side to the rhachis. 



* * Spikelets 2 or 8, rarely solitary, at each joint of the rhachis, placed with the florets dorso- 

 ventral to the rhachis. 

 +- Spikelets not all alike. 



Hordeum. Spikelets l(rarely 2-3)-flowered, in 3's at each joint, the lateral pair pediceled, 

 usually abortive ; glumes awn-like. 



-i- +- Spikelets all alike, 2-6-flowered. 



Elymus. Glumes usually equaling the florets ; spikes mostly dense. 



Hystrix. Glumes reduced to short bristles, one or both often obsolete ; spikes very loose. 



ibe XI. BAMBtSEAE. Tall woody reeds ; the flat blades with a short petiole articulated with 

 tlie sheath ; spikelets few-many-flowered, flattened, in panicles or racemes. 

 Arundinaria. Lemmas rounded on the back, many-nerved, acuminate or bristle-pointed; 

 glumes very small. 



