About Physematium oreganum subsp. oreganum
Physematium oreganum subsp. oreganum produces fronds (leaves) that are twice pinnate to pinnate-pinnatifid, meaning the second leaf division does not extend completely to the base. Fronds grow from a short, scaly rhizome. Individual plants sometimes grow as a single clump, but can form an elongated mass when the rhizome is longer. Mature fronds reach up to 25 cm in length and 12 cm in width, and are held in an upright to angled position. The rachis may have sparse, very short glandular hairs, and can be distinguished from the closely related Physematium scopulinum by the absence of long rachis hairs. Small round sori form on the underside of pinnae, and are initially partially covered by a narrowly lobed indusium. This subspecies typically grows in open rocky areas and on rock outcrops. It has a wide distribution across the western United States and southwestern Canada, with more scattered populations occurring further east.
