284 GRASSES OF IOWA. 



17. BROMUS. 



Bromus L. Sp. Pi. 76. 1753. Endlicher Gen. PI. 101. Bentham and 

 Hooker Gen. PI. 3: 1200. Hackel in Engler and Prantl Nat. Pflanz. Fam. 

 II. 2: 75. f. 88. Scribner. Bull. U. S. Dept. Agrl. 20: 156. f. 125. 



Schedonorus Beauv. Agrost. 99. 1812. 



Anisantha C. Koch. Linn. 21: 394. 1847. 



Serrafalcus Parlat. PI. Nov. 75 1842. 



Spikelets five to many-flowered, panicled. Glumes unequal, mem- 

 branaceous; the lower i to 5 (the upper 3-9) nerved. Flowering glume 

 either convex on the back or compressed-keeled, 5 to 9-nerved, awned 

 or bristle-pointed from below to the groove of the oblong or linear grain. 

 Stamens 3. Styles attached below at the apex of the ovary. Coarse 

 grasses, with large spikelets, at length drooping, on pedicels thickened 

 at the apex. (An ancient name for the oat, from a Greek word for 

 food.) 



Bentham <Sc Hooker and Hackel give the number of species at 40; 

 Bentham & Hooker divide the genus up into four sections. Beal lists 

 27 species native and introduced into North America. Monographers 

 in recent years have greatly increased the number of species; Shear in 

 his monograph recognizes 35 species, as occurring in North America. 

 Britton in his manual describes 14 species. 



KEY TO THE SPECIES OP BROMUS. 



A. Lower, empty glume one nerved, the upper three nerved. 



1. Perennial; >pmicle erect, contracted (except in flower); flowering 



glumes glabrous, awnless or merely awn-pointed ... .B. inermis? . 



2. Perennial; panicle open, its branches widely spreading or drooping; 



flowering glume pubescent; awn shorter than the glume. 



a. Empty glumes sparsely pubescent: flowering glumes sparsely 



over the back B. purgans." . 



(1) Sheaths densely soft pilose-pubescent throughout. 



— B. purgans var. incanus? . 



(2) Sheaths with a conspicuous, pilose-pubescent ring at the 



sum mit B. purgans var. latiglumis . ' . 



b. Empty glumes smooth; flowering glume densely appressed. 



pubescent on the margins for about three-fourths of its 



length B. ciliatus.^ . 



Flowering glumes smooth, or only slightly pubescent. 



— B ciliatus var. /aezig/umis ' . 



3. Low annual; panicle weak, open, its branches drooping; awn 12- 



16mm. long, longer than the hairy, flowering glume. 



— B. teciorum.' . 

 B. Lower empty glume 3-5 nerved, the upper 5-9 nerved. 

 1. Flowering glume pubescent. 



a. Panicle small open; flowering glume densely silky; awn 

 2- 3mm. long B. A'almii. 3 . 



