328 American Midland Naturalist Monograph No. 7 



Tribe 9. Paniceae. — Millet Tribe 

 1. Spikelets with an involucre of bristles or spine-bearing valves. 



2. Spikelets subtended by bristles; inflorescence a dense, spike-like panicle 

 72. Setaria 



2. Spikelets in a spiny involucre 73. Cenchrus 



1. Spikelets not involucrate. 



3. Glumes awned or awn-pointed 71. Echinochloa 



3. Glumes not awned. 



4. Glumes 2 68. Paspalum 



4. Glumes 3. 



5. Spikelets in slender, 1 -sided racemes 65. Digitaria 



5. Spikelets in panicles or racemes. 



6. Spikelets covered with long, silky, sii\ery hairs 66. Trichachne 



6. Spikelets not with silky, silvery hairs. 



7. Margins of lemma hyaline, flat 67. Leptoloma 



7. Margins of lemma not hyaline, more or less inrolled. 



8. Spikelets placed with the back of the fruit turned away from 



the rachis of the racemes 70. Eriochloa 



8. Spikelets placed with the back of the fruit turned toward the 

 rachis 69. Panicum 



Tribe 10. Andropogoneae. — Sorghum Tribe 

 1. Spikelets in slender racemes, these single or 2 or 3 together, not panicled 



74. Andropogon 



1. Spikelets in open or contracted panicles. 



2. Panicle densely pubescent; spikelets all perfect. 



3. Rachis continuous; leaves about 1 cm broad 75. Miscanthus 



3. Rachis jointed; leaves 1.2-2 cm broad 76. Erianthus 



2. Panicle not densely pubescent. 



4. Pedicelled spikelets staminate or neuter; panicle open; awns deciduous 



77. Sorghum 



4. Pedicelled spikelets reduced to a hairy pedicel; panicle narrow; awns 

 persistent 78. Sorghastrum 



Tribe 11. Tripsaceae. — Corn Tribe 

 1. Pistillate and staminate spikelets in different parts of the same inflores- 

 cence, the pistillate below 79. Tripsacum 



1. Pistillate spikelets in thick, axillary, solitary spikes ("cobs") ; staminate 

 spikelets in terminal paniculate spikes, forming the "tassel" 80. Zea 



Tribe 1. Bambuseae — Bamboo Tribe 

 1. Arundinaria Michx. — Cane 

 A. gigantea (Walt.) Muhl. River banks and swamps, s. 111., often 

 forming extensive colonies ("cane-brakes"). April-June; rarely flow- 

 ering. 



Tribe 2. Festuceae — Fescue Tribe 

 2. Bromus L. — Brome Grass 

 1. Plants perennial. 



2. First glume 1 -nerved (or 3-nerved in B. kalmii) ; second glume 

 3-nerved; lemmas not keeled. 



