3. Eriochloa, _H. B. & K._
These are annuals or perennials. Leaves are flat. The inflorescence is a raceme or a panicle. Spikelets are one-flowered, borne unilaterally on the branches, and the base is thickened and jointed on the top of a short pedicel. The spikelet has three glumes. The first and the second glumes are subequal, membranous. The third glume is apiculate, hardened in fruit. The lodicules are small and truncate. There are three stamens with linear anthers. Styles are two free, with plumose stigmas. The grain is oblong, free within the hardened glume and its palea.
[Ill.u.s.tration: Fig. 78.--Eriochloa polystachya.]
=Eriochloa polystachya, _H. B. & K._=
This gra.s.s is a densely tufted perennial, varying in height from 2 to 3 feet, with a short creeping root-stock. Stems are slender, or stout, simple and branching, ascending from a short creeping and rooting base, glabrous, slightly channelled on one side.
The _leaf-sheath_ is glabrous, green or partly purplish, striate, loose, mouth and margins above sometimes p.u.b.escent. The _ligule_ is a short villous ridge. _Nodes_ are perfectly glabrous.
The _leaf-blade_ is flat, linear or linear-lanceolate, ac.u.minate, glabrous on both sides, with a slender or prominent midrib, veins more or less uniform, 2 to 10 inches long and 1/6 to 1/3 inch wide, convolute when young. Sometimes the blade is purplish below.
The _inflorescence_ is a panicle on a long or short glabrous stalk, striate, 2 to 7 inches long, with four to fifteen erect or spreading, lax branches, the main rachis is glabrous, angular and deeply grooved.
Spikes or branches are slender, alternate, 1 to 2-1/2 inches, becoming shorter upwards, thickened and p.u.b.erulous at the base, and the secondary rachis is flexuous, grooved, angular, and obscurely p.u.b.escent.
[Ill.u.s.tration: Fig. 79.--Eriochloa polystachya.
1. A portion of the branch; 2, 3 and 4. the first, second and the third glume, respectively; 4a. back view of the third glume; 5. palea of the third glume; 6. lodicules, stamens and the ovary; 7. grain.]
The _spikelets_ are green or purplish, ovate, lanceolate, ac.u.minate 1/8 to 1/6 inch long, softly hairy, stalked, solitary above and binate below and then one with a long and the other with a short pedicel rising from a common short branchlet, loosely imbricate, distichous and shortly stipitate and the stipe with a purple thickening; pedicel is short, 1/24 to 1/12 inch with sometimes long deciduous hairs and the tip somewhat thickened.
There are three _glumes_ in the spikelet. The _first glume_ is membranous, covered densely with silky hairs, ovate-lanceolate, ac.u.minate, tip very minutely 3-toothed with three to five fine nerves.
The _second glume_ is similar to the first glume but with a more pointed tip, faintly 3- to 5-nerved; _palea_ is not present and if present it is very small, hyaline and empty. The _third glume_ is shorter than the first and the second glumes, thinly coriaceous, punctate, oblong, obtuse, pale, faintly 3- to 5-nerved with a short scaberulous awn, paleate; _palea_ is oblong, similar to the glume in texture, margin infolded. _Anthers_ are three, linear, pale yellow. _Stigmas_ are feathery, white when young and purple later. _Lodicules_ are two and distinct.
This is a common succulent gra.s.s growing in large or small tufts in moist situations such as sides of water channels, rivulets and bunds of paddy fields. It is very much liked by cattle. This gra.s.s is easily recognized by the silky lanceolate spikelets which have a purple thickening at the base.
_Distribution._--Plains of India and Ceylon and in all hot countries.
4. Panic.u.m, _L._
The gra.s.ses of this genus are annual or perennial and of various habits.
Inflorescence is either a raceme of spikes or, a lax or contracted panicle. Spikelets are small, solitary or two to four, rarely more ranked, 1- to 2-flowered, ovoid or oblong, rounded, or dorsally or laterally compressed, falling entire with the pedicels. There are four glumes in a spikelet. The first two glumes are empty and the first glume is small (sometimes minute) and fewest nerved. The second glume is equal or very nearly equal to the third glume, oblong-ovate or lanceolate, 5- to many-nerved. The third glume is similar to the second, male or neuter, paleate or not, 3- to 9-nerved. The fourth glume is chartaceous, sometimes shortly stalked, ovate-oblong or lanceolate, hardened in the fruit, smooth or rough, bis.e.xual, paleate; the palea is as long and of the same texture as the glume. Lodicules are cuneate or quadrate and two in number. There are three stamens and an ovary with two style branches ending in feathery stigmas. Grain is free and enclosed by the hardened fourth glume and its palea.
KEY TO THE SPECIES.
A. Inflorescence racemose of simple (rarely branched) spikes bearing secund spikelets.
I. Rachis of spikes broad and flattened.
(a) Spikelets biseriate.
Spikelets villous. 1. P. Isachne.
Spikelets glabrous.
Spikes shorter than the internodes. 2. P. flavidum.
Spikes longer than the internodes. 3. P. fluitans.
(b) Spikelets 3- to 5-seriate.
Third glume awned.
Stems stout, erect. 4. P. Crus-galli.
Stems stout, prostrate at base. 5. P. stagninum.
Third glume cuspidate.
Stems slender. 6. P. colonum.
II. Rachis of spikes narrow, filiform, terete or angular.
First glume shorter than the third.
First glume semilunate, about 1/4 of the third glume. 7. P. prostratum.
First glume 1/2 of or less than 1/2 of third glume, 5-nerved. 8. P. ramosum.
Leaf base broad or cordate.
Fourth glume shortly awned. 9. P. javanic.u.m.
Fourth glume muticous. 10. P. distachyum.
B. Inflorescence a contracted or open panicle.
I. Panicle contracted and spike-like.
Spikelets lanceolate and first glume minute. 11. P. interruptum.
II. Panicle effuse.
Annuals; first glume nearly 3/4 of the third glume. 12. P. trypheron.
Perennials; first glume less than 1/3 of the third glume. 13. P. repens.
[Ill.u.s.tration: Fig. 80.--Panic.u.m Isachne.]
=Panic.u.m Isachne, _Roth._=