2. Digitaria, Rich.
Annuals or perennials. The spikelets are lanceolate, 2- to 3-nate, in digitate or racemose spikes, jointed on the pedicels but not thickened at the base, 1-flowered. There are usually four dissimilar glumes in the spikelet. The first glume is hyaline very minute, sometimes absent in the same species. The second glume is membranous, 1- to 5-nerved or nerveless. The third glume is membranous, almost equal to the fourth, usually 7- to 9-nerved, the nerves being straight, close, parallel and prominent, with a minute palea or without a palea. The fourth glume is chartaceous or sub-chartaceous, usually 3-nerved and paleate; palea is equal to and similar to the fourth glume, 2-nerved. Lodicules are two, small, broadly cuneate. Stamens are three. Styles are distinct with plumose stigmas exserted laterally near the apex of the spikelet. Grain is enclosed in the fourth glume and its palea.
KEY TO THE SPECIES.
- Spikelets 1/10 inch or more.
- Spikes usually few, spikelets bearded 1. D. sanguinalis. Var. ciliaris.
- Spikelets not bearded 2. Do. Var. extensum.
- Spikes usually many; spikelets spreading 3. Do. Var. Griffithii.
- Spikelets less than 1/10 inch.
- Spikes narrowly winged; spikelets subsilky with slender (not clavellate) hairs 4. D. longiflora.
Fig. 71.—Digitaria sanguinalis, Var. ciliaris.