HITCHCOCK—-MEXICAN GRASSES, 
Lower lemma 3 mm. long; blades 
involute; panicle open, the 
branches spreading .......--- 
Spikelets more than 10-flowered. 
Culms tall, 1.5 to 2 meters high; 
blades 5 to 10 mm. wide...... 
Culms less than 0.5 meter high; blades 
narrow. 
Spikelets linear, 1.5 mm. wide; 
pedicels stiffly spreading, 
mostly longer than the 
spikelets ..........-.-..- 
Spikelets lanceolate, short-pedi- 
celed, lead-colored......- 
Plants annual. 
Palea conspicuously ciliate. 
Panicle open...--....-.-----------+-+--+--+- seeeeeeee 
Palea not conspicuously ciliate. 
Spikelets dicecious or polygamous; plants stolon- 
iferous... 2.2.22... 0. 2222 eee eee ee ee eee eee 
Spikelets perfect. 
Spikelets 3 mm. wide, usually about 1 cm. long; 
panicle more or less contracted; keel of 
lemma glandular-scabrous. .......-------- 
Spikelets not over 2mm. wide. 
Panicle contracted, the branches spikelet- 
bearing from the base; spikelets sub- 
sessile. 
Spikelets small, usually not over 3 mm. 
long; culms erect; panicles tawny, 
10 to 20 cm. long, narrow, inter- 
rupted below .........----------- 
Spikelets linear, many-flowered, as much 
as 15 mm. long; culms low and 
spreading; panicle mostly tinged 
with red, oblong, 2 to 5 cm. long, 
sometimes longer and somewhat 
compound.........----.---+------ 
Panicle open. 
[foliage hirsute; plants delicate, 10 to 20 
foliage glabrous. 
Panicle pilose in the lower axils; 
spikelets 1 mm. wide; lemma 
1.5 mm. long........--------- 
Panicle glabrous in the axils; spike- 
lets 2 to 2.5 mm, wide; lemma 
2mm. long. 
Panicle large and drooping, as 
much as 25 cm. long; 
spikelets 2 mm. wide....- 
18. 
16. 
20. 
10. 
9. 
359 
. €Tosa. 
. gigantea. 
. elliottit. 
. plumbea. 
. ciliaris. 
. plumosa. 
. hypnoides. 
. megastachya. 
. glomerata, 
. amoenda. 
. seribneriana. 
. pilosa. 
. mexicana. 
