Poaceae tribe Orcuttieae
Plants annual; viscid, aromatic. Culms with solid, pithy interiors, often with 5 or more nodes. Leaves with little or no distinction between sheath and blade; ligules absent; blades of upper cauline leaves similar in length to those below; siliceous cells of the leaf epidermis absent or irregular to dumbbell-shaped; microhairs of the blades bicellular, small, sunken, "mushroom-button" shaped. Inflorescences terminal, narrow, cylindrical to clavate or capitate, usually dense panicles or spikes, spikelets sessile or shortly pedicellate; rachillas tardily disarticulating between the florets. Spikelets with 4-25(40) florets. Glumes entire, denticulate, toothed, or absent; lemmas with 5-17 conspicuous veins; paleas subequal to or slightly shorter than the lemmas, well-developed, keels glabrous; lodicules absent or 2, obscure, rounded, truncate to slightly emarginate; anthers 3. Caryopses laterally compressed; hila large, punctate, basal; embryos 3/4 or more as long as the caryopses. x = 10.
|1||Lemmas deeply cleft into 5 mucronate or awn-tipped teeth, the teeth 1/3 as long as to equaling the lemma bodies; spikelets distichously arranged||Orcuttia|
|1||Lemmas entire or denticulate, often with a central mucro; spikelets spirally arranged.||> 2|
|2||Inflorescences clavate, often partially enclosed at maturity; spikelets laterally compressed, with glumes; lemmas rectangular, not translucent between the veins, the apices mucronate, otherwise entire or denticulate; caryopses without a viscid exudate, the embryo visible through the pericarp||Tuctoria|
|2||Inflorescences cylindrical, usually completely exposed at maturity; spikelets dorsally compressed, without glumes; lemmas flabellate, translucent between the veins, the apices ciliolate; caryopses covered with a viscid exudate, the embryos obscured by the pericarp||Neostapfia|