GUAMINEAB (GRASS FAMILY) 91 



64. Catabrosa. Spikelets 2-flowered. 



Lemmas 5-many-nerved (nerves often obscure in Briea). 

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



70. Dactylis. Spikelets flattened ; glumes and lemmas keeled, the keels hlspid-cillate. 



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

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



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



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



o. 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. 



0. Nerves of lemma not prominent. 

 f. Lemmas obtuse, awnless. 



74. Puccinellia. Glumes 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 thj apex. 



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



palea, pubescent at the summit. 



65. Helica. 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 subcorlaceous with a scarious margin, obtuse. 



Tribe X. HORDEAE. Spikelets (l-sveral-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 rhachia. 



78. Lepturus. Spikelets awnless; low branching annuals. 



i- - Spikelets 2-many-ttowered. 



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. 



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



usually abortive ; glumes awn-like. 



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



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



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



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



the sheath ; spikclrts few-m.iny-tlowered, flattened, in panicles or racemes. 



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

 glumes very small. 



