15. Perotis, _Ait._
These are slender annual or perennial gra.s.ses with short broad leaves.
Inflorescence is a spike or spiciform raceme. The spikelets are 1-flowered, sessile or shortly pedicelled and jointed. There are three glumes in the spikelet. The first and the second glumes are empty, subequal, narrowly linear with a strong midrib which is produced into a long capillary awn. The third glume is very small, hyaline, lanceolate, acute, 1-nerved and with a perfect flower; palea is small, narrow, hyaline and nerveless. Stamens are three with short anthers. Styles are short and united at the base with very short stigmas. The grain is long and narrow, longer than the flowering glume.
[Ill.u.s.tration: Fig. 124.--Perotis latifolia.]
=Perotis latifolia, _Ait._=
This gra.s.s is an annual with slender leafy stems, branching at the base, prostrate at first and then geniculately ascending, terminating in inflorescences and varying in length from 3 to 15 inches.
The _leaf-sheaths_ are glabrous, usually all short except the one next to the inflorescence which is two or three times as long as the lower sheaths. The _nodes_ are purple and glabrous.
The _leaf-blade_ is short, 1 to 1-1/4 inches long, ovate or lanceolate, cordate at base, acute and glabrous on both the surfaces; the margin is minutely serrate, rigidly ciliate and with a very narrow hyaline border.
The _inflorescence_ is a slender, crinite, spike-like raceme, 1 to 8 inches long, with a finely scabrid main _rachis_.
The _spikelets_ are narrow linear 1/12 to 1/8 inch or longer, purple, shortly pedicelled and 1-flowered, pedicels are short with a hyaline swelling on the upper side at the base.
[Ill.u.s.tration: Fig. 125.--Perotis latifolia.
1 and 2. Spikelets; 3, 4 and 5, the first, second and the third glume, respectively; 6. ovary, stamens and lodicules.]
There are three _glumes_. The _first_ and the _second glumes_ are empty, narrow-linear, purple, scabrid, 1-nerved and awned; awns are capillary, varying in length from 1/3 to 1/2 inch. The _third glume_ is very minute with very small palea. There are three _stamens_ and two small _lodicules_. _Styles_ are somewhat shorter. The grain is long and cylindric.
This gra.s.s grows in open waste places and in dry fields all over the Presidency.
_Distribution._--Throughout India.
CHAPTER VIII.
TRIBE IV--ANDROPOGONEae.
Andropogoneae is a very large tribe with about thirty genera. It is very well represented in South India and some genera are of very wide distribution.
The spikelets are usually arranged in pairs at each joint, one sessile and the other stalked. The spikelets may all be similar as in Imperata or they may be different as in Ischaemum and Andropogon. There may be only one flower in the spikelet as in Eremochloa and Saccharum or two as in Ischaemum and Apocopis. In the genera Polytoca and Coix the spikelets are unis.e.xual and the male and female spikelets are found in the same inflorescence, the female being below and the male being continuous with it. The spikelet nearly always consists of four glumes, the first or the first and the second being firmer and coriaceous or chartaceous. The flowering glumes are always shorter than the empty glumes, and are hyaline. The fourth glume is often awned or reduced to an awn.
The main rachis of the inflorescence is usually jointed at the base. In addition to this the rachis may be jointed all along its length, so as to become separated into distinct joints when mature as in Rottboellia, Saccharum and Andropogon, or it may be continuous as in Imperata. The pedicels of spikelets and the lower portions of the rachilla of the spikelets may have long hairs.
Sub. Tribe 1. =Maydeae.=
The spikelets are all unis.e.xual, spicate, the male and female spikelets are dissimilar, and are on the same or on different spikes.
Fruiting spikelets enclosed in a stony nut-like polished bract 16. Coix.
Fruiting spikelets with the first glume forming a crustaceous nut-like envelope to other glumes and grain 17. Polytoca.
Sub. Tribe 2. =Sacchareae.=
The spikelets are all similar, in compound racemes or panicles; the first glume not sunk in the hollow of the rachis. Spikelets are 1-flowered.
Rachis not fragile; spikelets in cylindrical silvery thyrsus 18. Imperata.
Rachis fragile; spikelets in open very much branched silky panicles 19. Saccharum.
Sub. Tribe 3. =Ischemeae.=
Spikelets many, dissimilar, in solitary, digitate or fascicled racemes or spikes; first glume not sunk in the hollow of the rachis.
Margins of the first glume of the sessile spikelet inflexed.
Spikes rarely solitary; spikelets binate, 2-flowered and awned 20. Ischaemum.
Spikes solitary; spikelets 1-flowered; first glume of the sessile spikelet pectinate 21. Eremochloa.
Margins of the first glume of the sessile spikelet not inflexed.
Spikes solitary or binate; spikelets 1- to 2-flowered, diandrous; first glume broad and truncate 22. Apocopis.
Spikes 2 or more; spikelets binate, upper alone awned 23. Lophopogon.
Sub. Tribe 4. =Apludeae.=
Spikelets three on an inarticulate rachis 24. Apluda.
Sub. Tribe 5. =Rottboellieae.=
Spikelets similar or dissimilar, 1- to 2-flowered, solitary, 2- or rarely 3-nate on the internodes of an articulated spike or raceme, not awned; the first glume is not keeled, sunk in a cavity of joints of the rachis; sessile spikelets 4-glumed.
Sessile spikelets single; first glume flat 25. Rottboellia.
Sessile spikelets geminate in all except the uppermost joints 26. Mnesithea.
Sessile spikelets binate; first glume globose, pitted 27. Manisuris.
Sub. Tribe 6. =Eu-Andropogoneae.=
Spikelets are dissimilar, 1-flowered, 2-(rarely) 3-nate on the whorled articulate branches of simple or compound racemes or panicles; glumes four, first glume not keeled, fourth glume usually awned.
Spikelets binate below and 3-nate at the top on a spicate or panicled inflorescence 28. Andropogon.
Spikelets in two superposed series. Upper series of one or more sessile bis.e.xual or female spikelets with one terminal pedicelled male spikelet.