The Manual of the Botany of the Northern United States / Including the District East of the Mississippi and North of North Carolina and Tennessee

by Asa Gray

[*] Spikelets in 2–4 ranks on a more or less flattened rhachis.—See also n. 5 (§ Digitaria).

[+] Rhachis produced beyond the upper spikelet; glumes 3.

1. Spartina. Spikelets much flattened laterally in 2 close ranks.

[+][+] Rhachis not produced above the upper spikelet (rarely in n. 3).

2. Beckmannia. Spikelets obovate, in 2 close rows. Glumes 3 (or 4), strongly concave, carinate.

3. Paspalum. Spikelets plano-convex, sessile or nearly so. Glumes 3 (rarely 2).

4. Eriochloa. Spikelets plano-convex, lanceolate, with a basal callus, short-pedicelled.

[*][*] Spikelets irregularly paniculate or spicate.

5. Panicum. Spikelets ovate, not involucrate nor the pedicels bristly. Glumes 4, the lowest usually small or minute.

6. Setaria. Spikelets in dense cylindrical spikes or panicles, the pedicels bristle-bearing.