274 



GRAMINEAE. 



Vol. I. 



99. BROMUS L. Sp. PL 76. 1753. 



Annual or perennial grasses, with flat leaf-blades and terminal panicles, the pedicels thick- 

 ened at the summit. Sheaths sometimes not split. Spikelets few-many-flowered. Two 

 lower scales empty, unequal, acute; flowering scales rounded on the back, or sometimes 

 compressed-keeled, 5-9-nerved, the apex usually 2-toothed, generally bearing an awn just 

 below the summit ; palet shorter than the scale, 2-keeled. Stamens usually 3. Stigmas ses- 

 sile, plumose, inserted below a hairy cushion-like appendage at the top of the ovary. Grain 

 adherent to the palet. [Greek name for a kind of oats.] 



About 60 species, most numerous in the north temperate zone. Besides the following, some 14 

 others occur in the western parts of North America. Type species : Bromus secalinus L. 



Lower empty scales i-nerved, the upper 3-nerved. 



Awns longer than the flowering scales; low annuals, ij4° tall or less. 



Flowering scales strigose, 4"-6" long. 1. B. tectorum. 



Flowering scales sparsely hispidulous, 6" long or more. 



Spikelets usually single on the long naked spreading branches. 2. B.sterilis. 



Spikelets several on the branches which are divided and spikelet-bearing above the middle. 



3. B. madritensis. 

 Awns shorter than the flowering scales, or wanting ; perennials 1*4° tall or more. 

 Flowering scales awned. 



Leaf-sheaths strongly retrorse-hirsute. 4. B. asper. 



Leaf-sheaths glabrous or softly pubescent. 



Blades 2"-6" wide ; panicle branches more or less spreading or drooping 

 Flowering scales pubescent on the margins only. 

 Flowering scales pubescent all over the back. 

 Blades less than 2" wide ; panicle branches erect. 

 Flowering scales awnless or merely awn-pointed. 

 Lower empty scale 3-nerved, the second one 5-9-nerved (3-nerved in no. 9). 

 Flowering scales rounded on the back, at least below. 



Perennials ; flowering scales densely pubescent with long silky hairs. 

 Second empty scale 3-nerved ; flowering scales $"-6" long. 

 Second empty scale 5-7-nerved ; flowering scales about 4" long. 

 Annuals. 



Flowering scales awned. 



Flowering scales pubescent with soft appressed hairs, not dense. 

 Flowering scales glabrous, or minutely roughened. 

 Awns straight. 



Fruiting scales with strongly inrolled margins, the nerves obscure ; leaf-sheaths 



glabrous. 

 Fruiting scales with the margins not inrolled, 

 sheaths softly and densely pubescent. 

 Spikelets broadly lanceolate, usually over 3' 



the longer branches. 

 Spikelets lanceolate, usually less than 3" 

 branches. 

 Awns bent near the base, divergent. 



Spikelets less than 2H" broad in flower. 



5. B. ciliatus. 



6. B. purgans. 



7. B. erectus. 



8. B. inermis. 



B. Porteri. 

 B. Kalmii. 



B. hordeaceus. 



12. B. secalinus. 

 the nerves prominent ; leaf- 



' wide, 

 wide, 



1 or sometimes 2 on 



13. B.racemosus. 

 several on the longer 



14. B. arvensis. 



Spikelets exceeding 2 l / 2 " broad, in flower. 

 Flowering scales awnless or awn-pointed, nearly as broad as long. 

 Flowering scales compressed, keeled. 



Flowering scales pubescent ; awn a"-3" long. 



15. B.patulus. 



16. B. squarrosus. 



1 7. B. brizaeformis. 



18. B. breviaristatus. 



Flowering scales minutely roughened; awn less than 1" long or wanting. 19. B.umoloiaes. 



i. Bromus tectorum L. Downy Brome-grass. Fig. 662. 



Bromus tectorum L. Sp. PI. 77. *7S3- 



Culms 6-2° tall, erect from an annual root, simple, 

 smooth and glabrous. Sheaths usually longer than the 

 internodes, at least the lower ones softly pubescent; 

 ligule i"-2" long; blades 1-4' long, 1 "-2" wide, softly 

 pubescent; panicle 2'-6' in length, open, the branches 

 slender and drooping, somewhat one-sided; spikelets 

 numerous, 5-8-flowered, on capillary recurved slender 

 pedicels; empty scales acuminate, usually rough or hir- 

 sute, the first i-nerved, the second longer, 3-nerved; 

 flowering scales 4"-6" long, acuminate, 7-nerved, usually 

 rough or hirsute; awn 6"-8" long. 



In fields and waste places, Maine to Ontario, Maryland, 

 Ohio and Missouri. Naturalized from Europe. Sometimes 

 a troublesome weed. May-July. 



