Isoëtes orcuttii A. A. Eaton, Fern Bull. 8: 13. 1900.
Isoëtes nuttallii A. Braun var. orcuttii (A. A. Eaton) Clute
Plants becoming terrestrial. Rootstock nearly globose 2(--3)-lobed. Leaves deciduous, bright green, pale toward base, less than 8 cm, gradually tapering to tip, often surrounded at base by several black scales to ca. 5 mm, spirally arranged, pliant, gradually tapering to tip. Velum covering entire sporangium. Sporangium wall unpigmented. Megaspores white to gray, lustrous, 200--380 μm diam., ± smooth to obscurely tuberculate; girdle obscure. Microspores brown in mass, 20--30 μm, smooth to papillose. 2n = 22.
Spores mature in spring. Vernal pools; mostly 0--1500 m; Calif., Mexico in Baja California.
Isoëtes orcuttii, a vernal pool endemic, may be difficult to distinguish from I. nuttallii, which occurs in a wider range of habitats. Plants of I. orcuttii are generally smaller than those of I. nuttallii, which has longer, thicker, less flexible leaves and larger megaspores.