GRAMINEAE (GRASS FAMILY) 91 



64. Catabrosa. Spikelets 2-flowered. 



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

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



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



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

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



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



& &. 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. 

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



Tribe X. HORDE AE. 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. 



+- +- 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 3, rarely solitary, at each joint of the rhachis, placed with the florets dorso- 

 ventral to the rhachis. 

 4- Spikelets not all alike. 



80. Hordeum. Spikelets l(rarely 2-3)-flowered, in 8's at each joint, the lateral pair pediceled, 



usually abortive ; glumes awn-like. 



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



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



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



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

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



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



glumes very small. 



