round the ovary.
Lodicules are two, linear or oblong-linear and hyaline. Stamens are
three. Styles are distinct. Grain is long, narrow and cylindrical.

KEY TO THE SPECIES.

Awn tripartite from the base and not articulate
with the top of the glume, persistent and
glabrous.

Annual.

Glumes I and II not awned.

Awn without any column and branched
from the base. 1. A. Adscenscionis.

Awn with a short column and with
shorter branches. 4. A. mutabilis.

Perennial.

Panicle cylindric, glumes I and II
awned; callus with white silky hairs. 2. A. setacea.

Panicle effuse, glumes I and II awned
or not; callus naked. 3. A. Hystrix.

Awn with a long column, tripartite at the top.

Annual; panicle lax, narrow; glumes I
and II awned. 5. A. funiculata.

[Illustration: Fig. 171.--Aristida Adscenscionis.]

=Aristida Adscenscionis, _L._=

This grass is usually an annual becoming a perennial under favourable
conditions. Stems are slender, sometimes even filiform, erect, or
ascending, simple or branched, varying in length from 9 inches to 3
feet.

The _leaf-sheath_ is glabrous, thinly striate. The _ligule_ is a row of
fine short hairs. _Nodes_ are glabrous.

The _leaf-blade_ is narrow, linear, tapering to a fine point, convolute
in bud, scabrid above and smooth below, with a minutely serrate, very
narrow, hyaline margin, 1 to 10 inches long and 1/12 inch broad.

The _inflorescence_ is a lax, narrow, subsecund panicle, varying in
length from 3 to 12 inches, and with a slender glabrous peduncle; the
main rachis is filiform and glabrous; branches are either solitary or
binate, unequal; branched either from the middle or the base; _pedicels_
are short and capillary.

[Illustration: Fig. 172.--Aristida Adscenscionis.

1. A spikelet; 2. first and second glumes; 3. palea; 4. lodicules,
stamens and ovary; 5. third glume with awns; 6. grain.]

The _spikelets_ are narrow, erect, green, occasionally also purplish,
1/4 to 1/3 inch long exclusive of the awn. There are three _glumes_. The
_first glume_ is linear-lanceolate, acute, membranous, 1-nerved with a
scaberulous keel, 1/16 to 3/16 inch long. The _second glume_ is longer
than the first, linear-lanceolate, acute, occasionally 2-toothed and
apiculate, 1-veined about 1/4 inch long and with a smooth keel. The
_third glume_ is as long as