50 American Midland Naturalist Monograph No. 2 



Tribe 10. Andropogoneae. — Sorghum Tribe 



1. Spikelefs In slender racemes, these single or 2 or 3 together, not panicled 



65. Andropogon 



l.Spikelets in open or contracted panicles. 



2. Panicle densely woolly; spikelets all perfect 66. Erianlhiis 



2. Panicle not woolly. 



3. Pedicelled spikelets staminate or neutral; panicle open; awns deciduous 



67. Sorghum 



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

 68. Sorghastrum 



Tribe 11. Tripsaceae. — Corn Tribe 



1. Pistillate and staminate spikelets in different parts of the same inflorescence, the pis- 

 tillate below 69. Tripsaciim 



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

 terminal paniculate spikes, forming the "tassel" 70. Zea 



1. Arundinaria Michx. — Cane 



A. gigantea (Walt.) Chapm. River banks and swamps, s. III., forming 

 "cane-brakes." \_A. macros perma Michx.} 



2. Bromus L. — Brome Grass 

 1. Plants perennial. 



2. Spikelets awnless or nearly so, 2-3.5 cm. long, nearly terete; panicle erect, 

 10-20 cm. long, the branches spreading; plants with rhizomes; fields and 



roadsides, introd. from Eur. May-June. Hungarian Brome Grass 



..B. inemiis Leyss. 



2. Spikelets conspicuously awned; native species. 



3. Lemmas pubescent on the margins and sometimes near the base, other- 

 wise glabrous; second glume 3-nerved; first glume 1-nerved; hillsides 



and open woods. June-Aug B. ciliatus L. 



3. Lemmas evenly pubescent. 



4. Panicle 10-30 cm. long; second glume 3-nerved; first glunie 1-nerved. 



5. Sheaths (except the lower one or two) shorter than the internodes; 



blades scarcely auriculate at base; meadows, woods, and banks. 



June-Aug. Canada Brome B. purgans L. 



5. Sheaths longer than the internodes; blades somewhat auriculate at 

 base; meadows and open woods, not cominon; known from Jo 

 Daviess, Kane, Stark, and Wabash counties. July-Sept. \B. alt'is- 



simus sensu Pursh, non Gilib.; B. incanus (Shear) Hitchc] 



B. latigliimis (Shear) Hitchc. 



4. Panicle 7-10 cm. long; second glume 5-7-nerved; first glume 3- 



nerved; dry ground. June-July B. kalmii Gray 



1. Plants annual; weedy species, adventive from Europe. 



6. Lemmas awnless or nearly so, scnrious-margined, glabrous or scaberulous, 

 nearly as broad as long; .spikelets broadly oval, 1.5-2.5 cm. long; fields 



and waste places; introd. from Eur. June-July 



B. hrizaejorniis F. & M. 



