52 



GRAMINEJE. 



of the uppermost flower-enclosing bractlet, and terminated by an 

 empty bractlet or a slender awn. Flower-enclosing bractlets like the 

 bracts in texture, keeled, 5-nerved, acuminate, ending in two long, 

 subulate teeth, with a long, bent and twisted awn arising from 

 between them; palea 2-nerved and 2-toothed. Ovary hairy or smooth; 

 stigmas almost sessile. Achene smooth, not furrowed. (Latin tres, 

 treis or tris, three, and saeta. a bristle, referring to the awn-like points 

 which terminate the bractlet in many species.) 



Panicle lax: branches more or less spreading or sub-erect. 

 Spikelets large, 6 to 12 lines long, 2 to 3 lines wide, 3 to 8-flowered, resembling 



those of a Bromus; rachilla nearly glabrous, bractlets hirsute 



1. T. barbatum. 



Spikelets small, 3 to 6 lines long, about 1 line wide, 2 to 3 (rarely 4)-flowered; 

 rachilla clothed with long hairs, bractlets sub-glabrous; lower bract less 

 than % as long as the upper; panicle-branches spikelet-bearing on the 



upper half 2. T. cermtum. 



Panicle contracted, strict; branches short, erect, the whorls not widely 

 separated. 



Spikelets small, about 4 lines long; lower bract only about ^ shorter than 

 the upper; bractlets imbricate, minutely puberulent; panicle-branches 

 mostly spikelet-bearing to the base 3. T. canescens. 



1. T. barbatum Steud. Brome-like Oat-grass. Annual; stem 

 usually solitary, 2 to 3 ft. high; sheaths hirsute with spreading hairs 

 arising from minute tuberculations, glabrescent in age; blades 6 in. 

 long, 2 to 3 lines wide, pilose-ciliate when young, sub-glabrous with 

 age; panicle lax, 4 to 9 in. long; branches slender, sub-erect, lower 

 bearing 2 to 4, upper only 1 spikelet; spikelets 6 to 12 lines long, 2 to 



3 lines wide, 5 to 8-flowered, much flattened, resembling those of a 

 Bromus; bracts narrow, acuminate, scabrous on the keel, 3-nerved, 

 nearly reaching to the apex of the nearest bractlet; internodes of the 

 rachilla short, nearly smooth; bractlet 5 to 6 lines long, hirsute all 

 over; teeth subulate; awn stout, twisted below, then bent outwards, 

 6 to 8 lines long. — (Bromus barbatoides, Beal.) 



Near thickets on hillsides, San Francisco, Bolander; also reported 

 from Oakland. Mar.-June. 



2. T. cernuum Trin. Nodding Oat-grass. Perennial: stems 2 

 to 3 ft. high, slender, in tufts; leaf-blades 6 to 9 in. long, 3£ to 6 lines 

 wide, sub-glabrous or sparsely pilose on the nerves, not ciliate; panicle 

 6 to 10 in. long, very open, drooping above; branches in remote 

 whorls, drooping, long, capillary, roughened, bearing 2 to 3 or rarely 



4 spikelets above the middle; spikelets 3 to 6 lines long, 1 line wide; 

 bracts very unequal, the lower narrow, subulate; upper more than .', 

 longer, broad, 3-nerved, obtuse and mucronate; rachilla clothed with 

 long, silky hairs, internodes 1 to H lines long, the lowest shorter than 

 the others, the terminal bearing an empty bractlet or a long, slender 

 awn; bractlet 2 to 3 lines long, glabrous or slightly scabrous; teeth 

 long and subulate; awn slender, about twice the length of its bractlet. 



Description drawn from Mendocino Co. specimens; reported from 

 San Franci>eo. .Mar.-June. 



3. T. canescens Buckl. Silvery Oat-grass. Perennial; stems 

 1 to 4 ft. high, stout, erect; sheaths varying from glabrous to pubes- 



