Plants annual; viscid-aromatic, more or less hairy throughout, not producing juvenile floating leaves. Culms 5-15(30) cm, simple or branching at the upper nodes, erect or ascending, often rather fragile, readily breaking apart at the nodes. Leaves without ligules, with little or no distinction between sheath and blade; blades flat, becoming involute when dry. Inflorescences terminal, clavate spikes, partially included or exserted at maturity, spikelets spirally arranged; disarticulation tardy, above the glumes and between the florets. Spikelets laterally compressed, with 5-40 florets. Glumes irregularly short-toothed or entire; lemmas (3)4-7 mm, 11-17-veined, not translucent between the veins, entire or denticulate, usually with a central mucro; paleas subequal to or slightly shorter than the lemmas; lodicules 2, 0.1-0.5 mm, sometimes fused to the paleas; anthers 3, exserted on long, slender, ribbonlike filaments at anthesis; styles 2, apical, long, filiform, stigmatic for 1/3-1/2 of their length; stigmatic hairs short, often sparse. Caryopseslaterally compressed, pyriform to oblong, pericarp not viscid; embryos visible through the pericarp, brown, from 3/4 as long as to nearly equaling the caryopses; epiblasts present. x = 10. Name an anagram of Orcuttia.

Tuctoria has three species, all of which grow in vernal pools or similar habitats, two in the Central Valley of California and one in Baja California Sur, Mexico. Both of the species found in the Floraregion are endangered by loss of habitat to urbanization and agriculture.

1.   Tuctoria greenei (Vasey) Reeder
Awnless Spiralgrass

Culms 5-15(30) cm, erect or decumbent, often geniculate; nodesoften purplish. Blades 1.5-5 cm long, to 5 mm wide, curved outward. Spikes 2.5-5(8) cm, exserted at maturity, congested above; lower internodes 4-5 mm; upper internodes 1-2 mm. Spikelets with 5-15(40) florets. Glumes subequal, 3-5 mm, prominently many-veined, irregularly dentate at the apices; lemmas (3)4-5(6) mm, prominently 9-13-veined, apices truncate and mucronate; paleas slightly shorter than the lemmas; anthers 3-3.5 mm, whitish; lodicules about 0.1 mm, not fused to the paleas. Caryopses about 2 mm, slightly compressed laterally, oblong, minutely rugose. 2n = 24.

Tuctoria greenei grows at elevations below 150 m in the Central Valley of California.

2.   Tuctoria mucronata (Crampton) Reeder
Prickly Spiralgrass

Culms to 12 cm, ascending, often decumbent or geniculate at the base; nodesusually concealed by the leaves. Blades 2-4 cm, involute, usually curved outward, tapering to a fine point. Spikes 1.5-6 cm, more or less included in the upper sheaths at maturity, congested throughout; internodes 1-2 mm. Spikelets with 5-10 florets. Glumes subequal (or the lower slightly shorter than the upper), 4-7 mm, mucronate, sometimes with 1 or 2 short lateral teeth; lemmas 5-7 mm, prominently 11-15-veined, apices erose or with a few minute teeth, central vein extending into a prominent mucro as much as 1 mm long; paleas slightly shorter than the lemmas; anthers about 3 mm, yellow, becoming pinkish in drying; lodicules about 0.5 mm, fused to the paleas. Caryopses about 3 mm, laterally compressed, broadly oblong, smooth. 2n = 40.

Tuctoria mucronata is known from only two locations in Solano County, California; both locations are at elevations below 10 m.