CHAPTER VIII.
TRIBE IV—ANDROPOGONEÆ.
Andropogoneæ 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 Ischæmum and Andropogon. There may be only one flower in the spikelet as in Eremochloa and Saccharum or two as in Ischæmum and Apocopis. In the genera Polytoca and Coix the spikelets are unisexual 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. Maydeæ.
- The spikelets are all unisexual, 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. Sacchareæ.
- 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. Ischemeæ.
- 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. Ischæmum.
- 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.
- Margins of the first glume of the sessile spikelet inflexed.