Trophophores converted entirely to second fertile segment, stalk 1/2 length of fertile segment. Sporophores double, 2 per leaf, 1-pinnate, 0.5--4 cm. 2 n =180.

Sporophores in June to August. Difficult to detect, plants usually hidden under other vegetation, in snowfields, secondary growth pastures; of conservation concern; 1500--3000 m; Alta., B.C., Sask.; Mont., Utah.

The leaf structure of Botrychium paradoxum is uniform and unique. Very rare teratological individuals of other moonwort species may have trophophores partially or wholly transformed into sporophores.

Botrychium × watertonense W.H. Wagner, known only from one locality in western Alberta, is the sterile hybrid of B . hesperium and B . paradoxum . It can be identified by its trophophore pinnae; all are bordered with sporangia. It may reproduce by some unknown mechanism, such as unreduced spores (W.H. Wagner Jr., F. S. Wagner, et al. 1984).