10 Isoëtes echinospora Dur.

Syn.: Isoëtes setacea auct., I. tenella Um. ex Desv.

The taxonomic conception of the lower taxa of this polymorphic species differs considerably among authors, as does the nomenclature (cf. Jermy in Brit. Fem. Gaz. 10/1969, p. 106). This map includes the European main type, considered as I. echinospora Dur. (var. echinospora), further var. braunii (Dur.) Engelm. (syn.: I. braunii Dur., I. muricata Dur.) within a large N. American area as also on Greenland and lceland, var. maritima Hult. (syn.: I. maritima Underw., I. truncata [A. A. Eat.] Clute) along the NW. American coast, and var. asiatica Hult. (syn.: l. asiatica [Makino] Makino) in easternmost Asia. Closely related taxa are reported from Barbados (named subsp. muricata) and Chile (I. savatieri Franch.). The species s. lat. belongs to the amphi-atlantic plants (Hultén, Amphi-atl. p. 254 and map 235), although it shows a tendency towards circumpolar distribution. Cf. also Meusel et al. 1965, map. p. 9. Knowledge of its occurrence seems still to be incomplete for large areas.