POACEAE 61 
Spathes narrow, long-acuminate, much exceeding the slender ra- 
cemes : sessile spikelet 3-4 mm. long, lanceolate. 9. A. tetrastachyus. 
Spathes broad, acuminate, equalling or shorter than the stout 
racemes: sessile spikelet about 4.5 mm. long, broadly lanceo- 
late. : 10. A. Mohrii. 
2. Racemes, at least some of them, entirely exserted from the spathes. the 
common peduncle thus visible. 
Sheaths at the summit of the stem and also sometimes at the upper 
nodes much enlarged, crowded and imbricated. 
All the flowering stems with enlarged upper sheaths; lower sheaths 
shorter than the internodes, hence distant. 
Basal sheaths and those of the innovations glabrous; enlarged 
sheaths in 2’s or 3’s, 3 mm. wide or less. ll. A. gracilior. 
Basal sheaths and those of the innovations densely hirsute; en- 
larged sheaths in 4's or more, 4-6 mm. wide. 12. A. Elliottii. 
Only some of the flowering stems with enlarged upper sheaths ; lower 
sheaths much exceeding the internodes, hence overlapping. 18. A. campyloracheus. 
Sheaths not enlarged. 
Spathes exceeding 10 cm. in length : racemes long and lax, the inter- 
nodes much exceeding the spikelets. 1BE IL 
Spathes less than 8 em. long : racemes short and stout, the internodes 
equalling or shorter than the spikelets. 
Inflorescence much branched, branches much divided; sheaths 
glabrous. 
Racemes 1-2 cm. long, the spikelets about twice as long as the 
rachis-internodes. 14. A. brachystachyus. 
Racemes 3-4 em. long, the spikelets equalling or little exceed- 
ing the rachis-internodes. 15. A. Floridanus. 
peace not much branched, the branches little or not at all 
ivided. 
Sheaths glabrous; racemes silvery white. 16. A. subtenuis. 
Sheaths hirsute; racemes brown. 17. A. arctatus. 
b. Stamens 3. 
First scale of the sessile spikelet appressed-hispid between the keels, rather 
thin: sheaths sometimes pubescent. 
First scale nerveless between the keels, or if intermediate nerves occur, 
not running the entire length of the scale: terminal hairs of the 
internodes about twice their length. i 18. A. argyraeus. 
First scale with 2 or 3 nerves between the keels, the nerves running the 
entire length of the scale: terminal hairs of the internodes about 
A 
campyloracheus. 
m. 
3 equalling them. ris 19. A. Cabanisii. 
First scale of the sessile spikelet glabrous and shining between the keels, 
firm : sheaths glabrous, and, with their blades, glaucous. 20. A. Scribnerianus. 
B. Pedicellate spikelet as large as the sessile, or larger, consisting of 4 scales and 
a staminate or rarely perfect flower. 
Stems tufted, no rootstocks. / 
Rachis-internodes of the racemes smooth : pedicellate spikelet staminate. 
Outer 2 seales of the sessile spikelet more or less hispidulous all over: 
hairs on the internodes usually 2 mm. long or less. 21. A. furcatus. 
Outer 2 scales of the spikelet glabrous, arp the nerves and also 
toward the summit of the first scale: hairs on the internodes 3-4 
mm. long, usually yellow. 1 ‘ 22. A. chrysocomus. 
Rachis-internodes of the racemes strongly hispidulous: pedicellate spike- 
let perfect. 23. A. Tennesseensis. 
Stems from long horizontal rootstocks. 24. A. geminatus. 
1. Andropogon glomeràtus (Walt.) B.S.P. Stems 5-15 dm. tall, commonly 
stout, the branches repeatedly and fastigiately branched, the lower ones somewhat elon- 
gated but considerably shorter than the stem, thus forming a large oblong glomerate pan- 
icle: leaf-blades 4 dm. long or less, 7 mm. wide or less, rough : spathes 2.5-3 cm. long, 
equalling or somewhat exceeding the racemes, smooth and glabrous, fastigiately crowded 
at the summit of the stem and ends of the branches : racemes in pairs, 1-2 cm. long: ses- 
sile spikelet 3-4 mm. long, the awn 10-15 mm. long, straight; pedicellate spikelet want- 
ing, or present as a subulate rudimentary scale. [.A. macrourus Michx. ] 
In low ground, Florida to Texas, New Mexico and Mexico. Fall.—A form with the racemes usu- 
ally more eye exserted from the apex of the narrow spathes which are tightly enrolled on the com- 
mon peduncle of the racemes, is known as A. glomeratus tenuispátheus Nash. 
2. Andropogon corymbósus (Chapm.) Nash. Stems 4-10 dm. tall, rather stout, 
from a little exceeding to twice as long as the basal leaves, the branches much divided, 
the lower ones elongated and nearly equalling the upper, thus forming a corymbiform 
panicle: leaf-sheaths keeled, those at the base much compressed and equitant, rough, often 
more or less papillose-hirsute, especially the shorter and crowded ones of the inflorescence ; 
stem-leaves with blades 3 dm. long or less, 5 mm. wide or less, rough : spathes very rough, 
narrow, tightly enrolled around the common peduncle of the raceme which is densely his- 
pidulous toward the summit and rather stout : racemes in pairs, more or less exserted from 
the summit of the spathes, 2-3 cm. long: sessile spikelet 4-5 mm. long, the awn 12-13 
mm. long, straight or nearly so ; pedicellate spikelet usually present as a subulate scale 
1-2 mm. long. [A. macrourus var. corymbosus Chapm. ] 
3 In wet soil, District of Columbia to Floridaand Mississippi. Fall.—A form differing from the type 
in having the spathes generally about equalling the racemes and few if any of them narrow and in- 
rolled on the peduncles is known as A. corymbosus abbrevidtus ( Hack.) Nash. It ranges as far north as 
Long Island, EK y 
