Andropogon.} clvii. gramine^ (Stapf). 209 
least from the middle upwards sharply indexed margins, 2-keeled, 
the upper more or less boat-shaped, keeled upwards, 3-1-nerved, 
sometimes aristulate. Valves ciliate or ciliolate, rarely glabrous, 
of lower floret hyaline, 2-nerved, of upper 2-fid or 2-dentate, hyaline 
or firmer and sometimes substipitiform below the insertion of the 
awn. Valvule a hyaline nerveless scale, or 0. Lodicules 2, minute, 
glabrous. Stamens 3. Stigmas laterally exserted ; styles terminal. 
Grain narrowly lanceolate to oblong in outline, subterete to plano- 
convex ; embryo about half the length of the grain. Pedicelled 
spikelets often very different from the sessile in shape and less 
so in size, always more or less compressed dorsally, never concave or 
channelled on the back, sometimes reduced and then often small or 
quite suppressed. Glumes herbaceous -chart aceous to membranous, the 
lower muticous or very rarely aristulate. Valves, if present, hyaline, 
ciliate, muticous. — Mostly perennial grasses of varying habit (see 
below). 
Species about 100, mostly in the tropics of both hemispheres. 
The genus Andropogon, even in the restricted sense in which it is understood 
here, is probably more heterogeneous than any other genus of Andropogonece. 
A. distachyus, Linn., has been accepted as its type, and the species immediately 
allied to it (about 12) are taken to constitute the subgenus Eu-Andropogon, an 
Old-World group. The remainder falls into 3 fairly natural groups which are 
only loosely connected with Eu-Andropogon and may even be entitled to rank 
as distinct genera. 
The total inflorescences of Andropogon and, to a still greater degree, of the 
immediately following genera are sometimes very complicated, and therefore 
require some explanation. The culms of Andropogon are either simple, termi- 
nating with a corymb or pair of racemes (very rarely with a single raceme), 
or they are branched; if branched, the branches (1) may be confined to the 
base, when they are either barren or mixed, that is, terminating with racemes 
after giving off a few barren leaves, or (2) the branches may extend over all 
the nodes of the culm, resulting in a suffrutescent habitus (24, A. cyrtocladus 
and 25, A. Bentii), or (3), they are restricted to the upper region, with a more 
or less pronounced tendency towards the formation of “false ” or spatheate 
panicles in which the branches, and their divisions, are specialised for the pro- 
duction of racemes. This is the usual type, to which the remarks below apply. 
Whether the culms be simple or divided, the corymbs or pairs of racemes 
always develop inside the sheath of a more or less modified leaf, and where such 
corymbs or pairs are gathered in groups, the groups behave in the same way. 
The modification of these protective leaves becomes the more pronounced the 
more composite the branching, and within the branch system, the nearer the leaf 
approaches to the summit or periphery. It finds its expression in a progressive 
suppression of the blade and in the widening and thinning, and the temporary 
or permanent inflation of the sheath. These m odified leaves are generally desig- 
nated “spathes.” More composite branching systems are often distinguished 
as having “ common ” and “ special ” spathes, according to whether they em- 
brace several branch-divisions or only the final elements. The “special” 
spathes are termed here “ spatheoles ” whilst all the others are simply spoken 
of as “subtending leaves” or “spathes” according to whether they more 
resemble the uppermost vegetative leaves or the spatheoles. 
As the racemes represent an easily recognizable definite and complex unit in 
the building up of the spatheate panicle, so they themselves enter into the 
formation of a still higher and more complex unit, marked off by the spatheoles 
from the system of axes that constitutes the framework of the panicle. This 
unit is made up of the raceme or racemes, the internode which serves as their 
EL. TROP. APR. VOL. IX. P 
