Tuctoria greenei

Grows in tufts of several unbranched stems 5-15 cm tall, erect or decumbent and breaking easily at the base. Entire plant often has soft shaggy hairs, but is only slightly sticky. Has purplish nodes and leaves 5 mm or narrower. Inflorescence can be up to 8 cm long; it may be partly hidden by the leaves when young, but is held above the leaves when mature. Inflorescence usually consists of 7-15 spikelets, but may contain up to 40. Spikelets are arranged in a spiral, with those in the upper half crowded together and those near the base more widely separated. Each spikelet has 5-15 florets and 2 glumes. Lemmas are 4-5 mm long and have squarish tips with 5-9 very short teeth; central tooth is tipped by a very small spine. Roughened seeds are about 2 mm long and weigh about 0.5 mg (USFWS 2005).

Differs from the closely related Tuctoria mucronata, found only in Solano and Yolo counties, by being larger in stature (30 cm vs. 12 cm), by its squarish lemma tip, by its smaller and roughened seeds, and in having inflorescences not included in the leaf (held above the leaf) when fully mature. Both can be told from the remaining Tuctoria species by stem length, seed shape, and range. The chromosome number of T. greenei also differs from the other two species in the genus. May also be confused with plants from the Orcuttia and Neostapfia genera. Neostapfia can be distinguished by its stout cylindrical spikes which look like tiny ears of corn. Orcuttia has its spikelets arranged in two rows on opposite sides of the spike (distichous) rather than spirally as in Tuctoria and has floating juvenile leaves (absent in T. greenei). Its short-toothed, narrow lemmas also distinguish T. greenei from Orcuttia and Neostapfia plants.
In general, the Orcuttieae tribe of grasses (Tuctoria, Orcuttia, and Neostapfia) differs from other grasses in (1) having a pith-filled (vs. hollow) stem, (2) producing 2-3 different types of leaves (vs. a single type) during their life cycle: cylindrical juvenile leaves which form underwater clustered into a basal rosette, and terrestrial leaves with flattened blades distributed along the stem, (3) having terrestrial leaves that are broad throughout with the lower portion enfolding the stem only loosely (vs. leaves differentiated into a narrow, tubular sheath that clasps the stem tightly and a broader blade that projects away from the stem), (4) having leaves which lack a ligule, and (5) producing an aromatic exudate, which changes from clear to brown during the growing season (USFWS 2005).

Grows in the bottom of dried Vernal Pools on the eastern side of the Sacramento and San Joaquin Valleys.Occurs in Northern Basalt Flow, Northern Claypan, and Northern Hardpan vernal pools (Sawyer and Keeler-Wolf 1995) on both low and high terraces within grassland communities, or, rarely, pine forest (one Shasta Co. occurrence). Plants have been documented on clay, loam, and stony clay loam soils, and pools are underlain by iron-silica cemented hardpan, tuffaceous alluvium, or claypan. Occupied pools range in size from 50 square meters to 3.4 hectares (median size 0.6 hectares). Tends to grow in shallower pools than its relatives (Neostapfia and Orcuttia) or on the shallow margins of deeper pools. Associated species include Eryngium castrense, Marsilea vestita, Eryngium vaseyi, Plagiobothrys stipitatus, Alopecurus saccatus, Chamaesyce hooveri, Orcuttia pilosa, O. inaequalis, O. tenuis, Neostapfia colusana, and Gratiola heterosepala. 30-135 m in Central Valley; 1100 m in Shasta Co. (one occurrence).

Grows in Vernal Pools. Common associates include; coyote thistle (Eryngium), spikerush (Eleocharis), Hoover's spurge (Chamaesyce hooveri), colusa grass (Neostapfia colusana), and hairy Orcutt grass (Orcuttia pilosa). Seeds are almost entirely dependant on a combination of anaerobic conditions and light for germination. Fungi may play a role in the germination process. Such cues are specific to the uppermost soil strata overlain by H2O for a significant period of time. This prevents seeds which are too deep from germinating, or germination in years when insufficient precipitation has fallen to allow the plant to complete its life cycle. seeds can persist for many years in the ground. The shrink/swell nature of the clay soils in the Central Valley act as conveyors to bring deeply buried seeds to the surface.