Publication: Mém. Soc. Linn. Paris 6: 179.
selected vouchers: WTU
Notes: FNA2: "North American plants of Isoetes echinospora, which bear stomata, have been called I. muricata or I. echinospora var. braunii to distinguish them from European plants of I. echinospora, which do not have stomata.
Isoetes echinospora is a distinct species but has considerable variation, especially in size, color, and form of leaves. It is the most commonly encountered quillwort in oligotrophic, noncalcareous lakes and ponds of northeastern North America.
Isoetes echinospora hybridizes with I. bolanderi; I. engelmannii [ = I. x eatonii Dodge (later synonym = I. x gravesii A. A. Eaton)]; I. lacustris [ = I. x hickeyi Taylor & Luebke]; I. maritima; I. riparia [ = I. x dodgei A. A. Eaton]; and I. tuckermanii."