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.

Discussion

The tribe Orcuttieae includes only three genera and nine species, all of which are restricted to vernal pools and similar habitats in California and Baja California, Mexico.

Selected References

Crampton, B. 1959. The grass genera Orcuttia and Neostapfia: A study in habitat and morphological specialization. Madrono 15:97-110

Reeder, J.R. 1965. The tribe Orcuttieae and the subtribes of the Pappophoreae (Gramineae). Madrono 18:18-28

Reeder, J.R. 1982. Systematics of the tribe Orcuttieae (Gramineae) and the description of a new segregate genus, Tuctoria. Amer. J. Bot. 69:1082-1095.

Lower Taxa

Neostapfia, Orcuttia, Tuctoria

Key

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