Isoëtes lithophila

N. Pfeiffer

Ann. Missouri Bot. Gard. 9: 135. 1922.

Common names: Rock quillwort
Treatment appears in FNA Volume 2.

Plants becoming terrestrial. Rootstock nearly globose, 2-lobed. Leaves deciduous, bright green, pale toward base, spirally arranged, to 12(–20) cm, pliant, gradually tapering to tip. Velum covering entire sporangium. Sporangium wall unpigmented. Megaspores light gray to gray-brown, 290–360 μm diam., obscurely rugulate with low ridges; girdle obscure. Microspores brown in mass, 30–33 μm, tuberculate to spinulose. 2n = 22.

Phenology: Spores mature in winter or spring.
Habitat: Shallow depressions on granite outcrops


Isoëtes lithophila is known from granite outcrops in Burnett, Mason, and Llano counties in south central Texas.

Of conservation concern.

Selected References


Lower Taxa