A Handbook Of Some South Indian Grasses Part 19

These are tall perennial gra.s.ses. Inflorescence is a much branched open panicle, branches spreading or erect, capillary and fragile. Spikelets are small, 1-flowered, binate, one sessile and the other pedicelled, the sessile spikelet is bis.e.xual and the pedicelled is female and rarely bis.e.xual; sessile spikelets are deciduous with the contiguous joint of the rachis and the pedicel. There are four glumes. The first glume is chartaceous, equal in length to the second, oblong or lanceolate. The second glume is concave. The third glume is hyaline, empty. The fourth glume is very small or absent. Lodicules are present. There are three stamens. Stigmas are laterally exserted. Grain is oblong or sub-globose.

=Saccharum spontaneum, _L._=

This is a tall perennial gra.s.s with a creeping root-stock bearing erect stems and occasionally dec.u.mbent or prostrate stolons. Stems vary in length from 5 to 20 feet. Branches and axillary buds grow out piercing the sheaths near the nodes.

The _leaf-sheath_ is glabrous, but woolly at the mouth. The _ligule_ is a distinct ovate membrane. The _nodes_ are glabrous.

The _leaf-blade_ is very long, narrow linear, ac.u.minate and narrowing downwards into the stout midrib, coriaceous, glabrous and 1-1/2 to 2 feet by 1/8 to 1/4 inch.

The _panicle_ is lanceolate, 8 to 24 inches, silky and the peduncle just below the panicle is softly silky, branches are whorled, three to five at a level, 2 to 4 inches long, rachis of the branches almost capillary, jointed and fragile, joints with long cilia at the back.

The _spikelets_ are binate, one sessile and another pedicelled, both bis.e.xual and alike, lanceolate, 1/8 to 1/6 inch long, callus is minute and bearded with spreading silky hairs 1/2 inch long.

[Ill.u.s.tration: Fig. 129.--Saccharum spontaneum.

1. Two spikelets; 2, 3, 4 and 5. the first, second, third and the fourth glume, respectively; 6. ovary, stamens and lodicules.]

There are four _glumes_. The _first glume_ is lanceolate, subulate, ac.u.minate, 2-nerved, flattened dorsally, coriaceous at the base and hyaline above it, and with smooth incurved margins. The second _glume_ is about equal to or slightly shorter than the first, lanceolate, ac.u.minate, 1-nerved, keeled with an opaque base; margins and keel are ciliate with fine long hairs. The _third glume_ is hyaline, ovate-lanceolate, nerveless, acute, ciliate. The _fourth glume_ is very slender, ciliate, ac.u.minate, paleate; _palea_ is minute, very variable.

_Stamens_ are three. _Lodicules_ are cuneate or quadrate. The grain is very small, oblong.

_Distribution._--This occurs all over India along the sides of the river.

20. Ischaemum, _L._

The gra.s.ses of this genus are either annuals or perennials. The inflorescence consists of spikes, solitary, digitate or fascicled, articulate and fragile; the joints of the floral axis and the pedicels of the pedicelled spikelets are trigonous and hollowed ventrally.

Spikelets are binate, one sessile and one pedicelled; the pedicelled spikelets are dissimilar from the sessile and both usually 2-flowered.

The sessile spikelets have four glumes. The first glume is coriaceous, oblong or lanceolate, convex more or less, marginally winged above the middle, truncate or two-cuspidate at the apex and awnless. The second glume is as long as the first, coriaceous, concave, acute or obtuse, awned or not. The third glume is hyaline, deeply cleft into two lobes with an awn in the cleft, and 3-nerved, paleate; palea is linear-lanceolate enclosing either stamens and ovary or ovary alone.

Lodicules are cuneate or quadrate.

KEY TO SPECIES.

Racemes two or three; the first glume of the sessile spikelet dorsally flat, not channelled or depressed along the middle line.

Margin of the first glume of the sessile spikelet incurved narrowly from the base to the apex.

First glume of sessile spikelets with nodulose margins. 1. I. aristatum.

First glume of sessile spikelets closely transversely ribbed. 2. I. rugosum.

First glume of the sessile spikelet translucent, bicuspidate at the tip and with smooth margins. 3. I. pilosum.

Margin of the first glume of the sessile spikelet broadly incurved from below the middle.

First glume of the sessile spikelet with smooth margins, callus bearded. 4. I. ciliare.

Raceme solitary; the first glume of the sessile spikelet deeply grooved at the back along the middle line. 5. I. laxum.

=Ischaemum aristatum, _L._=

This is a perennial gra.s.s, with fairly stout, erect or somewhat dec.u.mbent, simple or branched, glabrous, leafy stems, 1 to 4 feet high.

The _leaf-sheath_ is loose, glabrous and auricled. The _ligule_ is a distinct membrane, broad or narrow. _Nodes_ are glabrous.

The _leaf-blade_ is linear-lanceolate, flat, ac.u.minate, narrowed towards the base which may be acute, subcordate or rarely even petiolate, glabrous or spa.r.s.ely hairy above and glaucous beneath, 4 to 10 inches long and 1/4 to 1 inch broad.

The _inflorescence_ consists of one or two, erect, stout or slender, fragile racemes, 1 to 5 inches long.

[Ill.u.s.tration: Fig. 130.--Ischaemum aristatum.

1. A portion of the raceme showing the joints, sessile and pedicelled spikelets; 2, 3, 4 and 6. the first, second, third and the fourth glume, respectively, of the sessile spikelet; 5 and 7. palea of the third and the fourth glumes, respectively; 8. ovary, stamens and lodicules; 9.

first glume of the pedicelled spikelet.]

The _spikelets_ are 1/6 to 1/3 inch long, the sessile and the pedicelled closely pressed together, glabrous or hairy; the callus of the sessile spikelet broad and thick, with or without hairs. The _sessile spikelet_ is awned and consists of four glumes. The _first glume_ is 1/5 inch long or less, oblong or linear-oblong, cartilaginous below the middle, with two to four (or rarely up to six) marginal nodules on each edge, sometimes these are connected by shallow ridges, thinner above the middle, with green anastomosing veins, tip obtuse or 2-toothed, and margins narrowly incurved. The _second glume_ is chartaceous, lanceolate, ac.u.minate, 1-nerved and with a smooth rounded keel. The _third glume_ is ovate-lanceolate, membranous, 1-nerved, ac.u.minate, male or bis.e.xual with an oblong palea. The _fourth glume_ is cleft to or below the middle into lanceolate acute lobes, with a brownish red awn 1/2 inch or more long at the sinus twisted at the lower portion and straight above, paleate, usually female; _palea_ is linear oblong. The _pedicelled spikelet_ is as long as the sessile, inarticulate on the very thick, short pedicel which is densely or spa.r.s.ely hairy at the base. The _first glume_ is scimitar-shaped, coriaceous, acute, with a somewhat semi-circular wing. The other _glumes_ are as in sessile spikelets, but the fourth glume has no awn and may have a mucro.

This gra.s.s is a variable one. There is much variation in the breadth of the leaves and in the markings and hairiness of the spikelets. The spikelets may be glabrous or hairy and the marking in the first glume of the sessile spikelets varies in the matter of marginal nodules--it may have mere shallow notches or deep well-formed nodules and there may be transverse ridges or they may be absent. This gra.s.s is abundant on the West Coast and rare in the East Coast.

_Distribution._--Throughout the plains and lower hills of India and Ceylon.

[Ill.u.s.tration: Fig. 131.--Ischaemum aristatum.

A. A portion of the raceme showing the joints; B. a sessile and a pedicelled spikelet. 1, 2, 3 and 6. the first, second, third and the fourth glume, respectively; 4 and 5. palea of the third and the fourth glume; 7. ovary and lodicules; 8. first glume of the pedicelled spikelets.]

=Ischaemum rugosum, _Salisb._=

This is an erect annual gra.s.s with tufted, leafy, compressed stems varying in length from 10 inches to 2 feet.

The _leaf-sheath_ is glabrous, loose and compressed, with a membranous auricle confluent with the truncate _ligule_. _Nodes_ usually glabrous but sometimes also p.u.b.erulous.

The _leaf-blade_ is narrow, linear-lanceolate, flat, base contracted, flaccid, ac.u.minate, rounded at the base, glabrous or spa.r.s.ely hairy on both the surfaces; the topmost leaf is often reduced to an inflated sheath enclosing the inflorescence partially.

[Ill.u.s.tration: Fig. 132.--Ischaemum rugosum.

1. A part of the raceme showing sessile spikelets with reduced pedicelled spikelets; 2. a sessile spikelet and a well developed pedicelled spikelet; 3. a reduced pedicelled spikelet; 4, 5, 6 and 8.

the first, second, third and the fourth glume of the sessile spikelet; 7 and 9. palea of the third and fourth glumes of the sessile spikelet; 10.

ovary.]

The racemes are usually two, erect, fragile, 1 to 3 inches long with a slight thickening of the peduncle below the inflorescence; the joints are 1/3 to 2/3 as long as the sessile spikelets; trigonous and subclavate, and with long hairs on one side. The _spikelets_ are linear-oblong, glabrous or villous, 1/8 to 1/4 inch long, sessile and stalked spikelets close together; the pedicel of the stalked spikelet is thick about 1/3 or less than the length of the sessile spikelet, ciliate on one side, confluent with the thick callus of the sessile spikelet, which is spa.r.s.ely bristly. The _sessile spikelet_ consists of four glumes and is awned. The _first glume_ is concave, pale yellow, shining and cartilaginous to about 2/3 its length from the base, and the upper third is membranous, dimidiately ovate; at the back in the cartilaginous portion, there are three to six deep convex smooth ridges running across the glume; the membranous tip is thin and with anastomosing green veins; the margins of this glume are thick, narrowly incurved, ciliolate, and with a narrow wing on the outer margin. The _second glume_ is oblong-lanceolate or lanceolate, coriaceous, ac.u.minate, scaberulous, keeled and laterally compressed and on the keel just below the tip there is a narrow ciliate wing. The _third glume_ is ovate-lanceolate, hyaline, ac.u.minate 1- to 3-veined, male or empty, with a narrow hyaline palea. The _fourth glume_ is shorter than the third, deeply cleft into two lanceolate acute lobes, 3-veined at the base; awn up to about 2/3 inch long; _palea_ is linear lanceolate. Stamens are three and _lodicules_ are small and cuneate.

The pedicelled spikelet is very variable. It is shorter than the sessile, with obscure transverse ridges and may consist of four glumes, but without an awn to the fourth glume; sometimes this spikelet is reduced to a single glume.

The grain is broadly oblong, brownish and compressed.

_Distribution._--Throughout India and Ceylon.