This marsh-gra.s.s is found in marshy places such as ditches and channels in paddy fields, ponds and tanks.

_Distribution._--It is found all over India and Ceylon; also in Africa, America and Australia.

12. Hygrorhiza, _Nees._

These are floating glabrous gra.s.ses with stems diffusely branching and profusely rooting at the nodes. The inflorescence is a panicle. The spikelets are 1-flowered, with a solitary flowering glume only. The flowering glume is awned, strongly 5-nerved, nerves scabrid and ciliate, the lateral nerves being marginal. Palea is 3-nerved, narrow ac.u.minate with a ciliate keel. Lodicules are suborbicular. There are six stamens with long slender anthers. Styles are free with plumose stigmas, laterally exserted. Grain is oblong, narrowed at the base, obtuse, free within the glume and its palea.

=Hygrorhiza aristata, _Nees._=

This is a floating aquatic gra.s.s. Stems are spongy, branching diffusely, 1 foot long, with feathery whorled roots in dense ma.s.ses at the nodes; branches are short, erect and leafy.

The _leaf-sheath_ is smooth, inflated, compressed, with ciliate margins.

The _ligule_ is a narrow membrane. _Nodes_ have whorls of roots.

The _leaf-blade_ is linear or ovate-lanceolate, obtuse, glabrous, glaucous beneath, base rounded or subcordate, 1 to 3 inches long and 1/2 to 3/4 inch broad.

The _inflorescence_ is a panicle, 2 inches long and broad, somewhat triangular in outline; the _rachis_ and the branches are stiff, slender and smooth, the lower branches are a little deflexed.

[Ill.u.s.tration: Fig. 120.--Hygrorhiza aristata.

1. Branch; 2. part of a leaf with ligule; 3. spikelet; 4 and 5. glume and its palea; 6. lodicules and ovary.]

The _spikelets_ are very narrow, sessile or pedicellate, articulated on the pedicel, 1-flowered and 1-glumed. The _glume_ is about 3/8 inch long (excluding the awn) and the awn is as long as the glume or slightly longer, lanceolate, with five strong nerves and the lateral ones forming thickened margins; the palea is as long as the glume. _Stamens_ are six and _lodicules_ two.

Found in ponds and tanks.

_Distribution._--All over India and Ceylon.

13. Trachys, _Pers._

These are softly, villous, diffuse annual gra.s.ses. The inflorescence consists of usually two (rarely three) divaricating spikes on a long peduncle. The rachis is herbaceous, broad flexuous, jointed and bearing at each joint a solitary globose cl.u.s.ter of two or three perfect 1-flowered glabrous spikelets surrounded by many short spinescent glumes of imperfect ones. The perfect spikelets are 4-glumed and the glumes are very unequal. The first glume is minute, tooth-like, nerveless. The second glume is long, linear-lanceolate, membranous, very acute, strongly 3- to 5-nerved. The third glume is the largest, obliquely ovate, or obovate-oblong, cuspidately ac.u.minate, rigidly coriaceous, 9- to many-nerved, paleate or not, empty. The fourth glume is shorter and narrower than the lower one, linear-oblong, ac.u.minate, chartaceous, smooth, dorsally convex, with incurved margins, bearing a bis.e.xual flower, paleate, palea is hyaline as long as the glume, and the margins are inflexed below the middle. Lodicules are very minute or wanting.

There are three stamens. The styles are very long with slender stigmas, exserted at the top of the glume. The grain is oblong, compressed, free within the glume and its palea.

=Trachys mucronata, _Pers._=

This is a diffusely branching, softly villous annual gra.s.s. The stems are many from the root, 16 to 18 inches long, ascending or dec.u.mbent and prostrate, leafy, glabrous, rooting freely at the lower nodes, especially when proc.u.mbent.

The _leaf-sheaths_ are loose, inflated, hairy or rarely glabrous. The _ligule_ is a thin membrane, or a ridge of fine closely set hairs.

_Nodes_ are villous.

The _leaf-blade_ is linear-lanceolate to ovate-lanceolate ac.u.minate, flaccid, softly villous on both the surfaces, margins often crisped, base rounded, 2 to 6 inches by 1/4 to 1/2 inch.

The _inflorescence_ consists of a long or short, slender, s.h.i.+ning peduncle bearing two or three rigid, flattened, flexuous, jointed spikes, the rachis is broad, herbaceous, with a flat, broad, closely nerved wing on both the sides and with a distinct flat midrib and jointed, each joint bears on the under surface at the articulation, a solitary, globose cl.u.s.ter of two to three perfect 1-flowered glabrous spikelets surrounded by many short spinescent glumes of imperfect ones.

The spikes vary in length from 1 to 2 inches and in breadth from 1/10 to 1/6 inch and are glabrous.

The cl.u.s.ters of _spikelets_ are about 1/4 inch in diameter, often partially sunk, in a concavity of the rachis; the perfect spikelets are 1/5 to 1/4 inch long and the imperfect are shorter.

[Ill.u.s.tration: Fig. 121.--Trachys mucronata.

A and B. The spikelets; 1, 2 and 3. the first, second and the third glume, respectively; 4. palea of the third glume; 5 and 6. the fourth glume and its palea; 7. lodicules, ovary and stamens.]

In the perfect spikelet there are four very unequal glumes. The _first glume_ is minute, tooth-like, triangular or lanceolate, acute, nerveless, 1/16 to 1/12 inch long. The _second glume_ is elongate, linear-lanceolate, acute, sometimes ciliate below the middle, membranous, narrower than the third glume, hyaline, strongly 3-nerved, 1/16 by 1/6 inch. The _third glume_ is 1/5 by 1/8 inch the largest in the spikelet, broadly and obliquely ovate or obovate, cuspidately acute, with nine to many green nerves, paleate; the _palea_ is very small, about 1/20 inch long, oblong, hyaline and rigidly coriaceous. The _fourth glume_ is much narrower and shorter than the third glume, linear oblong, ac.u.minate, chartaceous, smooth, dorsally convex, with incurved margins, bis.e.xual and paleate; the palea is as long as the glume, ac.u.minate, hyaline, the margins inflexed below the middle, ovate, acute.

_Lodicules_ are minute or absent. _Stamens_ are three with linear anthers. _Styles_ are very long with slender stigmas. The grain is oblong, compressed.

This gra.s.s grows abundantly in cultivated dry fields and in the sand near the sea-sh.o.r.e and it is easily recognized by the cl.u.s.ters of spikelets in the spike.

_Distribution._--The Deccan Peninsula--both in the interior and on the sea coast.

14. Tragus, _Haller._

These are annual or perennial gra.s.ses, with erect or prostrate stems.

Inflorescence is a spiciform raceme, bearing the spikelets in cl.u.s.ters of 2 to 4. The spikelets are 1-flowered and usually with two glumes.

Sometimes a very minute hyaline lower glume is present. The first glume is thickly coriaceous, 5-ribbed, oblong-lanceolate, and ribs with long recurved spines. The second glume is oblong or oblong-lanceolate, apiculate, chartaceous, 3-nerved and with a perfect flower; palea is as long as the glume, 2-nerved. Lodicules are broad, cuneate and fleshy.

There are three stamens. Styles are slender and distinct, with narrow stigmas exserted from the top of the glume. Grain is oblong to ellipsoidal free within the glume and its palea.

[Ill.u.s.tration: Fig. 122.--Tragus racemosus.]

=Tragus Racemosus, _Scop._=

This plant is a perennial with tufted prostrate or erect stems, rooting at the nodes freely and densely leafy. The flowering branches are erect or geniculately ascending and varies from a few inches to about a foot.

The _leaf-sheath_ is short, pale, glabrous, somewhat compressed, striate, equitant below and upper are longer, terete and green. The _ligule_ is only a ridge of short, fine hairs. _Nodes_ are glabrous.

The _leaf-blade_ is convolute when young, ovate or ovate-lanceolate, variable from 1/4 to 2 inches long and 1/10 to 1/6 inch wide, ac.u.minate, flat or somewhat wavy, glabrous on both the surfaces, rigidly pungent, densely crowded and distichously imbricate in the lower part of the stem, base is amplexicaul, and the margin is distantly serrate and rigidly ciliate.

The _inflorescence_ is a spike-like terminal panicle varying in length from 3/4 to 2 inches; the _rachis_ is wavy, slender, angular or grooved, p.u.b.escent, the peduncle is striate, p.u.b.escent and enclosed by the leaf-sheath.

The _spikelets_ are arranged in groups of two, facing each other and appearing like a single spikelet with two equal echinate glumes, sessile, or obscurely pedicelled on very short, tumid, p.u.b.escent branches.

[Ill.u.s.tration: Fig. 123.--Tragus racemosus.

1. A pair of spikelets; 2, 3 and 4. the first, second and the third glume, respectively; 5. palea of the third glume; 6. ovary, anthers and lodicules.]

There are two (rarely three) _glumes_ in the spikelet. The _first glume_ is very minute, hyaline, obtuse and it is very often not present. The _second glume_ is about 1/8 inch, ovate-lanceolate, ac.u.minate, strongly 3-ribbed with rows of stout, spreading hooked spines along the ribs and encloses a single floret. The margins of this glume are membranous and somewhat scaberulous. The _third glume_ is about 1/12 inch, oblong lanceolate, membranous minutely hairy, 3-nerved and finely pointed at the apex; the _palea_ is as long as the glume, hyaline, 2-nerved, lanceolate, subacute and irregularly toothed at the apex. _Stamens_ are three, with slender filaments, anthers are short, broad and pale yellow.

The style branches are pale and feathery. _Lodicules_ are two, fleshy and cuneate or subquadrate. The grain is free inside the glume and the palea, linear oblong, slightly compressed and pale brown, the embryo occupies about 1/3 the length of the grain.

This is one of the commonest gra.s.ses growing everywhere in tufts with usually prostrate branches. In some situations the branches are erect.

_Distribution._--Plains of India throughout and Ceylon. It is found in all the warm regions of the world.