Isoetes Isoetes, Bory

11. I. histrix Bory View in CoL , Compt. Rend. Acad. Sci. (Paris) 18: 1167 (1844)

( I. delalandei Lloyd , I. phrygia Hausskn. ).

Terrestrial; stem 3-lobed. Leaves 5-10 cm x 0- 5—1 -0 mm, more or less flat, linear; stomata numerous; membranous margin wide at base, narrowing abruptly just above sporangium but continuing up the leaf for 1 -2 cm; leaf-bases persistent over several years as black, shiny, horny scales with central, short, broad lobe and two longer lateral, often spine-like lobes. Sporangium completely covered by velum; megaspores 400-560 p, with small tubercles which often become confluent, especially on the basal surface; microspores brown, spinulose. 2« = 20. Sandy places, where water lies in winter, from cliff-tops to open pinewoods. Mediterranean and Atlantic coasts of Europe, northwards to 50° N. Br Co Cr Ga Gr Hs It Ju Lu Sa Si.

This species is variable in the size and ornamentation of both types of spores and in the form of the persistent leaf-bases.