Pumice grape-fern – State Wildlife Action Plan

Photo Credit: Oregon Department of Agriculture

Pumice grape-fern is a perennial with a stout, fleshy underground stalk about 10 cm long, usually bearing a single leaf divided into sterile and fertile parts. The sterile portion of the leaf (trophophore) is dull, grayish green, glaucous, sessile or nearly so, the blade up to 4 cm long by 6 cm wide, usually ternately divided, the middle segment largest, each segment further divided pinnately into overlapping ascending, roundish, asymmetrically cuneate segments with wavy to crenate margins, the lower pinnae often lobed. The trophophore appears to originate near ground level, although it is located high on the subterranean common stalk. The fertile portion of the leaf (sporophore) is 1-3-pinnate, 1-1.5 times the length of the trophophore, with a short stalk and very compact sporangial cluster.

Overview

Species Common Name Pumice grape-fern
Species Scientific Name Botrychium pumicola
State Listing Status Threatened

Ecoregions

East Cascades

The East Cascade ecoregion extends from the Cascade Mountains' summit east to the warmer, drier high desert and down the length of the state. This ecoregion varies dramatically from its cool, moist border with the West Cascades ecoregion to its dry eastern border, where it meets sagebrush desert landscapes.

West Cascades

The West Cascades ecoregion extends from east of the Cascade Mountains summit to the foothills of the Willamette, Umpqua, and Rogue Valleys, and spans the entire length of the state of Oregon. It is largely dominated by conifer forests, moving into alpine parklands and dwarf shrubs at higher elevations.

Special needs

Pumice grape-fern is an alpine and montane species found on loose volcanic (pumice) soils. It is typically associated with alpine scree, lodgepole pine, or antelope bitterbrush frost-pockets. This species often occurs on open, flat, high-elevation ridgetops and gently-rolling slopes. Pumice grape-fern emerges in years when conditions are sufficiently moist.

Limiting factors

Small size makes this species vulnerable to trampling. Pumice grape-fern is adversely affected by fire suppression (closing canopies) and timber harvest that compacts soil. Facilities, roads, or trails can eliminate suitable habitat. The species is moderately vulnerable to climate change, primarily due to predicted increased variability in temperatures and precipitation and its dependence on specific habitat conditions.

Data gaps

Identify protected populations. Investigate whether the Newberry pumice plume represents a special habitat type for pumice grape-fern. Note the uncertainty of annual surveys for this species because of unpredictable emergence patterns.

Conservation actions

Avoid disturbing ground at known sites of occurrence, unless activities are specifically designed to maintain or enhance pumice grape-fern. Monitor known populations.

Key reference or plan

An interagency Conservation Strategy for pumice grape-fern was developed by the U.S. Forest Service and U.S. Bureau of Land Management in 2001. An interagency Conservation Assessment for 13 Botrychium species, including B. pumicola, was completed by the U.S. Forest Service and U.S. Bureau of Land Management in 2007.