124 NORTH AMERICAN FLORA [VorumE 17 
23. AMPHILOPHIS Nash, in Britton, Man. 71. 1901. 
Perennial grasses with usually flat leaf-blades and showy often silvery-white panicles, 
the axis short, making the panicle appear fan-like, or elongate with the branches scattered. 
Racemes usually numerous, the internodes of the rachis and the pedicels with manifestly 
thickened margins, the median portion thin and translucent, the margins ciliate with usually 
long hairs. Spikelets in pairs, dorsally compressed. Sessile spikelet of 4 scales, perfect, or rarely 
the lower pair or pairs staminate or empty; first scale 2-keeled, the margins narrowly infolded; 
second scale 1-keeled; third scale hyaline; fourth scale stipe-like, the blade wanting, somewhat 
thickened, merging into a usually geniculate perfect, rarely imperfect, awn, or the awn rarely 
warting. Pedicellate spikelet awnless, staminate and similar to the sessile one, or empty and 
smaller. Stamens 3. Styles distinct. Stigmas plumose. 
Type species, Andropogon Torreyanus Steud. 
Sessile spikelets in all pairs alike, perfect, awned, very rarely awnless. 
Pedicellate spikelet as wide and long as the sessile one, consisting of 3 or 4 scales, usually 
staminate, rarely empty. 
Sessile spikelet 3-4 mm. long, the first scale appressed-pubescent be- 
low on the back. 1. A. Ischaemum, 
Sessile spikelet more than 5 mm. long, the first scale glabrous, or very 
rarely with a few scattered hairs below. 
Racemes erect, on peduncles usually 1 cm. long or less; awn of the 
sessile spikelet 1-1.5 cm. long. 
Racemes nodding, on peduncles usually 1-2.5 cm. long; awn of the 
sessile spikelet 2-2.5 cm. long. 3. A. hirtifolius. 
Pedicellate spikelet much narrower than the sessile one, and sometimes 
shorter, commonly empty and reduced to a single scale, or very 
rarely of 2 or 3 scales and staminateé. 
Hairs at the summit of the rachis-internodes more than one half as 
long as the sessile spikelet. 
First scale of the sessile spikelet not pitted. 
Sessile spikelet 34 mm. long; awn usually less than 1.5 cm. 
long; panicle oblong to oval-oblong, the axis elongate. 4. A. saccharoides. 
Sessile spikelet 5mm. long or more; awn more than 1.5cm. long; 
panicle usually corymbiform or flabellate-digitate, the axis 
short. 5. A. leucopogon. 
First scale of the sessile spikelet with a pit near the apex. 
Leaves glabrous; rachis-internodes with the terminal hairs as 
BN 
. Wrightii. 
long as theniselves. 
Leaves velvety-pubescent; rachis-internodes with the terminal 
hairs one half their length. 
Hairs at the summit of the rachis-internodes less than one half the 
6. A. emersus. 
7. 
length of the sessile spikelet. 8. A. Schlumbergeri. 
9, 
A, Palmeri. 
Sessile spikelet in the lower pair or pairs differing from those above, awn- 
less, staminate or empty. 
1. Amphilophis Ischaemum (1,.) Nash. 
Andropogon Ischaemum \,. Sp. Pl. 1047. 1753. j 
Andropogon Ischaemum americanus Hack. in DC. Monog. Phan. 6: 476. 1889. 
Sorgum Ischaemum Kuntze, Rev. Gen. 792. 1891. 
A. piptatherus. 
Stems 3-8 dm. tall, often barbed at the nodes, simple or sparingly branched above; leaves 
often glaucous; sheaths glabrous; blades 5-20 cm. long, up to 6 mm. broad, narrowly linear, 
usually with a few long hairs on the upper surface near the base, otherwise glabrous; racemes 
4-10, rarely more, 4-8 cm. long, slender, lax, subflabellately arranged on a short axis; sessile 
spikelet 3-4 mm. long, oblong-elliptic, the first scale 7-9-nerved, the intercarinal space flat 
or nearly so, appressed-pubescent below, often with a pit-like depression near the apex, the 
second scale ciliate above on the keel, the fourth scale with a perfect awn 1-2 cm. long, the 
column straight or somewhat geniculate at the middle; pedicellate spikelet glabrous, stami- 
nate, lanceolate, usually colored, the first scale ciliate above on the keels, 9-nerved. 
TYPE LOCALITY: India. 
DISTRIBUTION: Introduced from Venezuela to Antigua and St. Croix; native of warm temper- 
ate and tropical regions of the Old World. 
ILLUSTRATIONS: Host, Gram. Austr. 2: £/.2, Sturm, Deuts. Fl. 52: f/. 12; Nees, Gen. Fl. 
Germ. Andropogon. 
2. Amphilophis Wrightii (Hack.) Nash. 
Andropogon Wright Hack. Flora 68: 139. 1885. 
Sorgum Wrightit Kuntze, Rev. Gen. 792. 1891. 
