KEY TO THE SPECIES
Base of involucel rounded; inner bristles shorter, erect, not ciliate 1. C. biflorus.
Base of involucel turbinate, inner bristles longer, spreading and spinescent, ciliate at base 2. C. catharticus.
=Cenchrus biflorus, _Roxb._=
This is an annual with erect simple stems, 6 to 24 inches long.
The _leaf-sheath_ is glabrous or nearly so, with hairs at the mouth.
The _leaf-blade_ is linear-lanceolate, finely ac.u.minate, glabrous or hairy, 3 to 10 inches long and 1/8 to 3/8 inch broad.
The _inflorescence_ is a solitary cylindric raceme of involucels, 2 to 4 inches long, enclosed in the uppermost leaf-sheath; the _rachis_ is flexuous, angular and smooth. _Involucels_ usually with two, rarely three spikelets, loosely imbricate, rounded at the base; the inner bristles are erect, dorsally flat, subulate-lanceolate, p.u.b.erulous and with thickened margins, about 1/8 inch long. The outer are shorter than the inner, glabrous, erect or subsquarrose and as long as the sessile spikelets.
The _spikelets_ are about 1/6 inch long, sub-globose, with four _glumes_. The _first glume_ is about 1/10 inch long, ovate-ac.u.minate, very thin, hyaline, nerveless or rarely 1-nerved. The _second glume_ is broadly ovate, 1/6 inch long, hyaline, acute, 1-nerved. The _third glume_ is slightly longer than the second, oblong-ovate, apiculate, 5-nerved and paleate; _palea_ 1/8 inch obtuse. The _fourth glume_ is as long as the third, ovate, obtuse, paleate. _Anthers_ are three. _Styles_ free almost to the base. The grain is 1/12 by 1/16 inch orbicular oblong, compressed, smooth and pale brown.
[Ill.u.s.tration: Fig. 117.--Cenchrus biflorus.
1. A portion of the raceme; 2. an involucel; 3, 4, 5 and 7. the first, second, third and the fourth glume respectively; 6 and 8. palea of the third and the fourth glumes; 9. the ovary and stamens; 10 grain.]
This gra.s.s is not so widely distributed as _Cenchrus catharticus_. It is confined to some East Coast districts.
_Distribution._--The Punjab, Gangetic plain, Concan, Sind and Coromandel. Also said to occur in Africa and Arabia.
=Cenchrus catharticus, _Delile._=
A tufted annual gra.s.s with geniculately ascending stems, branching at the base.
The _leaf-sheath_ is glabrous and somewhat inflated. The _ligule_ is a fringe of hairs. _Nodes_ are glabrous.
The _leaf-blade_ is linear-lanceolate, finely ac.u.minate, 1 to 4 inches long and 1/8 to 1/4 inch broad.
The _inflorescence_ is usually enclosed in the leaf-sheath, 1 to 6 inches long; the _rachis_ is flexuous, angular and glabrous. The involucels are 1/4 to 1/2 inch across, turbinate or truncate at base with an outer, shorter and inner longer series of hard, sharp, pungent spines; the inner subulate, dorsally deeply grooved, very much longer than the spikelets; margins ciliate to about half the distance from the base, and the upper half covered with very short, sharp and stiff, reflexed hairs; the outer are shorter than the spikelets, spreading or erect, glabrous or nearly so and covered with reflexed hairs.
The _spikelets_ are usually one to two and rarely three in an involucel and each one has four _glumes_. The _first glume_ is lanceolate and nerveless or ovate-lanceolate and 1-nerved, half as long as the third glume, hyaline and acute. The _second glume_ is about 1/6 inch long, ovate, acute, membranous, 5-nerved. The _third glume_ is similar to the second, paleate; _palea_ is lanceolate and short. The _fourth glume_ is as long as the third, cuspidately ac.u.minate, membranous, 5-nerved and paleate; _palea_ is ovate, as long as the glume. _Stamens_ are three.
_Styles_ are free and long with plumose stigmas. The grain is ovoid-oblong, brown and compressed.
[Ill.u.s.tration: Fig. 118.--Cenchrus catharticus.
1. A portion of the spike; 2. an involucel with two spikelets; 3, 4, 5 and 7. the first, second, third and the fourth glume respectively; 6 and 8. palea of the third and the fourth glume respectively; 9. the ovary and stamens; 10. grain.]
This gra.s.s is more common than _C. biflorus_ and is found on the East Coast districts in open sandy places.
_Distribution._--Nellore, Bellary, the Punjab and the Gangetic Plains.
CHAPTER VII.
TRIBES II AND III--ORYZEae AND ZOYSIEae.
=Oryzeae= is a very small tribe with a few genera, which usually flourish in marshes. The spikelets are in panicles, 1-flowered and the flower is usually perfect. In Oryza there are three glumes, the first two being very minute, and there is only a single glume in Leersia and Hygrorhiza.
There are usually six stamens. The palea becomes firm in texture like the glume instead of remaining hyaline, and so it is often mistaken for a glume. The spikelets are jointed on their pedicels and fall away from them.
Not floating; spikelet not awned 11. Leersia.
Floating; spikelets awned 12. Hygrorhiza.
=Zoysieae= is another small tribe with half a dozen genera. The inflorescence is either a spike-like raceme or a spiciform panicle. The spikelets are solitary in Perotis, binate in Tragus and grouped in Trachys. There is usually a complete flower in a spikelet and the glumes are membranous. Mature spikelets are deciduous with their pedicels singly in Perotis and in cl.u.s.ters in others.
Spikelets fascicled unilaterally on a broad rachis, 4-glumed, glumes not echinate 13. Trachys.
Spikelets binate and all round the rachis, 3-glumed, glumes echinate 14. Tragus.
Spikelets single, awned and 3-glumed 15. Perotis.
11. Leersia, _Sw._
These are tall perennial marsh gra.s.ses. The inflorescence is usually a more or less contracted panicle with very slender branches. The spikelets are compressed and consist of only one glume bearing a perfect flower. The solitary flowering glume is chartaceous, awnless, 3- to 5-nerved, the lateral nerves forming the thickened margin of the glume.
The palea is narrow, linear-lanceolate, as long as the glume, 3-nerved, rigid, dorsally ciliate, and with hyaline margins. Lodicules are two.
Stamens are usually six in number. Styles are short, with plumose stigmas and laterally exserted. Grain is ovoid or oblong, compressed, free within the glume and its palea.
=Leersia hexandra, _Sw._=
This is a slender perennial marsh-gra.s.s with stems rooting in the mud and with flexuous floating branches, sending up erect or ascending, weak and slender leafy branches, 2 to 4 feet high.
[Ill.u.s.tration: Fig. 119.--Leersia hexandra.
1. Erect branch; 2 and 3. bits of leaves with ligules; 4 and 5.
spikelets; 6. ovary and lodicules.]
The _leaf-sheath_ is smooth, glabrous, with eciliate margins. The _ligule_ is a short obliquely truncate or two-lobed membrane. _Nodes_ are hairy with deflexed hairs.
The _leaf-blade_ is flat, narrow, linear, tapering to a fine point, suberect and rather rigid, glabrous and with a narrow base, varying in length from 3 to 10 inches and 1/8 to 1/3 inch in breadth.
The _inflorescence_ is an oblong laxly branched, narrow pedunculate panicle, 2 to 4 inches long.
The _spikelets_ are all 1-flowered and 1-glumed, articulate on the pedicels above the rudimentary glumes, strongly laterally compressed.
The _glume_ is about 1/6 inch long, ovate-oblong, somewhat boat-shaped, acute and shortly mucronate, strongly keeled, ciliate on the keel and margins, 5-nerved, the lateral nerves forming a thickened margin; _palea_ is as long as the glume, linear-lanceolate, subacute, rigid with membranous margins. _Stamens_ are six and there are two small _lodicules_. The first two glumes are reduced to an obscure hyaline rim.