Physematium oreganum subsp. oreganum

Frond Structure

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.

Rhizome and Growth Form

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.

Frond Size and Posture

Mature fronds reach up to 25 cm in length and 12 cm in width, and are held in an upright to angled position.

Rachis Characteristics

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.

Sori and Indusium

Small round sori form on the underside of pinnae, and are initially partially covered by a narrowly lobed indusium.

Habitat

This subspecies typically grows in open rocky areas and on rock outcrops.

Distribution

It has a wide distribution across the western United States and southwestern Canada, with more scattered populations occurring further east.