Vascular Plants of the Gila Wilderness

Presented in Association with the
Western New Mexico University Department of Natural Sciences

Key to the genus Argyrochosma in the Gila National Forest

The genus Argyrochosma is represented by only two species in the Gila National Forest: Argyrochosma limitanea subsp. mexicana and Argyrochosma fendleri. This genus is easily separable in the field from the Pellaeas, to which they are closely related, by the presence of the whitish powdery substance farina found on the underneath (abaxial) surface of the pinnules in Argyrochosma.

1. Rachis remains stout and linear, the costae branching off at regular angles of about 45 degrees. The pinnules are strongly revolute over about half the surface, appearing rolled. The branching pattern looks like this .....Argyrochosma limitanea subsp. mexicana.
1. Rachis bends easily and may angle away from the costae at the takeoff points especially distally, becoming hard to distinguish from costae more distally on the frond. The hydrated pinnules not revolute over most of the surface, appearing flat. The branching pattern looks more like this .....Argyrochosma fendleri.

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