, Colorado Weed Seeds 29 
10. Porcupine Grass, Spear Grass 
iStipa L.) 
. Lemma terminating in a single, stiff awn twisted one-half to three- 
quarters its length, straight near the tip, the straight portion bent at an 
angle of 60° to 90°; palet inclosed within the hardened lemma; rachilla 
reduced to a hard and sharp point at the base and armed with a tufted ring 
of short, stiff hairs directed upwards ; seeds S-20 mm. long, 1-1.5 mm. wide. 
Key to Species 
\ Seeds 18-20 mm. long, I-I .5 mm. wide; awn prominently 
twisted 1 CY 
1 . . S. spartea 
Seeds 10-12 mm. long, 1 mm. wide; awn twisted indistinctly.. 2..S. comata 
Fig, 27. Por- 
i cupine Grass 
i (Stipa spartea). 
^ X 3. 
1. Porcupine Grass {Stipa 
spartea Trin.) (Fig. 27).— Seeds 
clay color, hairy at base; lemma 
somewhat shiny; awn bent one-half 
its length, 12-15 cm. long. 
2. Western Stipa (Stipa 
comata Trin. & Rup.) (Fig. 28). 
Seeds straw-yellow in color, hairy 
at base; lemma dull; awn nearly 
straight, 10-12 cm. long. 
Fig. 28. West- 
ern Stipa (Stipa 
comata). X 2)4. 
11. Brome Grass 
(Bromus L.) 
I Lemma convex or keeled, 5-9 veined or nerved, usually two-toothed at 
the apex, bearing a sub-terminal awn ranging from a mere blunt point to a 
f slender, hair-like projection as long or longer than the seed; palet a little 
shorter than the lemma, two-keeled ; rachilla cylindrical, very short, one-tenth 
j to one-fifth the length of the seed, smooth or hairy ; seed 6-12 mm. long, 1.5 — 4 
I mm. wide, many species widely flaring at the apex; grain flat, furrowed, 
. dark reddish-brown in color, 5-8 mm. long. 
Key to Species 
1 Seeds plump, distinctly rounded on the back; lemma 
smooth or nearly so 1 r> « t 
; 1.. Bromus secahnus 
s Seeds thin, flat to slightly round on the back ; lemma 
very hairy throughout 
2.. Bromus tectorum 
