XIII. Pedicularis howellii Gray (Howell's lousewort)

Area of Application: Throughout the area covered by the Northwest Forest Plan.

A. Introduction

Pedicularis howellii is an herbaceous perennial green root parasite in the Scophulariaceae (figwort) plant family. Howell's lousewort is the common name most frequently applied to this species.

Pedicularis howellii is considered to be closely associated with old-growth habitat, and is classified as a Survey and Manage Strategy 1 and 2 species under the FSEIS/ROD (USDA Forest Service and USDI Bureau of Land Management 1994a, 1994b). It is listed on List 4, "limited distribution", by the California Native Plant Society (Skinner and Pavlik 1994). P. howellii is on List 2 (threatened or endangered in Oregon, but more stable or common elsewhere) by the Oregon Natural Heritage Program (1998), and it is a Bureau of Land Management Assessment Species in Oregon and Washington. This species is managed as a Sensitive species on all 4 National Forests where it occurs due to its local endemism.

B. Unique Characteristics, Biology, and Ecology

The following is a technical description of Pedicularis howellii:

Perennial herb, glabrous to the inflorescence; stem rather stout, 3-4.5 dm high, naked toward the base; basal leaves none, the cauline ovate or oblong ovate in outline, cleft and parted with 3 to 7 more or less serrate or toothed segments, sometimes merely denticulate or mainly entire, 3-5 cm long, slender petioled; flowers in a short, dense spike, with ovate, denticulate bracts that are basally woolly; calyx campanulate, woolly villous, the lobes very short; corolla 8-10 mm long, pale yellowish or white, the sometimes rose colored galea short beaked, strongly arching over the much shorter, obscurely lobed lover lip (Meinke 1982; after Peck 1961).

Pedicularis howellii can be confused with a related species, P. racemosa, but it can be distinguished from P. howellii on the basis of its 2 lobed calyx and its long, narrow, undivided leaves.

Bumblebees may be involved in pollination of Pedicularis howellii (USDA Forest Service and USDI Bureau of Land Management 1994b). Flowering occurs in June and July (Meinke 1982). Seed set and seed germination in the field are high. Seed germination is patchy, typically concentrated in the vicinity of the maternal parent plant. P. howellii may require nearly saturated soil for germination, but later stages are probably intolerant of poor drainage. Sufficient snowpack to provide soil moisture during the blooming season may be an important limiting factor. Longer distance dispersal may be facilitated by animals (e.g., deer, chickarees, squirrels) since the density of plants is often high along game trails. This species may require disturbance (e.g., fire, windthrow, root rot centers) to maintain population viability. Interspecific competition may limit P. howellii (USDA Forest Service and USDI Bureau of Land Management 1994b).

C. Specific Habitat Associations

This species is found in partial shade or along the edges of forest openings in a variety of conifer/shrub plant associations. Associated species commonly include Abies magnifica, A. concolor, Picea breweriana, Tsuga mertensiana, and Pinus monticola, over a 30-80 percent shrub understory typically including Quercus sadleriana, Vaccinium membranaceum, and Ceanothus prostratus. Habitat is found primarily on northern exposures ranging from 1280-1921 m (4200-6300 ft.) elevation (Barker and Maercklein 1984; USDA Forest Service and USDI Bureau of Land Management 1994b). It does not appear to be limited to a particular habitat, plant association, or seral stage, but does seem dependant upon a specific suitable soil moisture regime (Barker and Maercklein 1984) and the apparent need for heimiparasitic root attachments to adjacent host plants (Macior 1986). Pedicularis howellii is more abundant in open forest (USDA Forest Service and USDI Bureau of Land Management 1994b) where the mixed-conifer canopy is most commonly less than 40 percent (Barker and Maercklein 1984). The most common micro-habitats within mature forest stands are light gaps (USDA Forest Service and USDI Bureau of Land Management 1994b) and the edge of forest canopy openings, where sunlight favors development of plants to the flowering stage (Macior 1986). Populations are most commonly found along natural or man-made forest edges such as streams, lakes and wet meadows (30%), trails or roads (40%), and other forest canopy openings (Barker and Maercklein 1984). Populations there have higher densities and greater vigor (Barker and Maercklein 1984) and produce the greatest proliferation of seedlings (Macior 1986). Natural forest occurrences that can provide these habitat niches include fire, windthrow, high water tables, and pockets of frost or disease that remove the conifer overstory (Barker and Maercklein 1984; USDA Forest Service and USDI Bureau of Land Management 1994b).

Climate within the range of Pedicularis howellii is characterized by short, cool, dry summers and wet, cold winters. Precipitation averages between 203-305 cm (80-120 inches), with much of it falling as snow. Approximately 68 percent of known populations occur on aspects of northeast to northwest. Substrate is variable, including ultramafic, metasedimentary, and granitic. Soils are commonly shallow and skeletal with surface textures nearly always loams to clay loams.

D. Range of Pedicularis howellii

1. Known Range

Pedicularis howellii is found only in the Siskiyou Mountains, within the Klamath Mountains Province of southwestern Oregon and northwestern California. Approximately 85 occurrences straddle the California/Oregon border along the Klamath/Siskiyou National Forests border, and range southwest along the Klamath/Six Rivers National Forest borders in California (Williams 1996). All known sites are on National Forest lands, with no likely habitat expected to be on private lands. About 47 percent of the plants are managed by the Klamath NF, 35 percent by the Siskiyou NF, 15 percent on the Rogue River NF, and 3 percent just inside the Six Rivers NF (Barker and Maercklein 1984).

2. Suspected Range

Populations of this species are not expected beyond the currently known range.

E. Timing of Surveys

Surveys should be conducted during the flowering or fruiting periods (June through August) when plants are most easily identifiable.

F. Threats

Threats to Pedicularis howellii include fire suppression, clearcut timber harvesting, mechanical site preparation, cattle grazing, trail and road construction, and recreation (Meinke 1982; USDA Forest Service and USDI Bureau of Land Management 1994b).

REFERENCES

Barker, L. and D. Maercklein. 1984. Pedicularis howellii Botanical Investigation Report and Management

Recommendations. Unpub. report on file, Klamath National Forest.

Macior, L. W. 1986. Pollination Ecology and Endemic Adaptation of Pedicularis howellii Gray (Scrophulariaceae). Pl. Sp. Biol. 1: 163-172.

Meinke, R. J. 1982. Threatened & Endangered Vascular Plants of Oregon: An Illustrated Guide. U. S. Fish and Wildlife Service, Portland, OR. 352 pp.

Oregon Natural Heritage Program. 1998. Rare, Threatened and Endangered Species of Oregon. Oregon Natural Heritage Program, Portland, Oregon. 92 pp.

Peck, M. E. 1961. A Manual of Higher Plants of Oregon (Second edition). Oregon State University Press, Corvallis, OR.

Skinner, M. W., and B. M. Pavlik. 1994. California Native Plant Society's Inventory of Rare and Endangered Vascular Plants of California. The California Native Plant Society. Sacramento, CA.

USDA Forest Service and USDI Bureau of Land Management. 1994a. Final supplemental environmental impact statement on managing of habitat for late successional and old-growth species within the range of the northern spotted owl. Portland, Oregon.

USDA Forest Service and USDI Bureau of Land Management. 1994b. Final supplemental environmental impact statement on managing of habitat for late successional and old-growth species within the range of the northern spotted owl. Appendix J2, Results of Additional Species Analysis. Portland, Oregon.

Williams, B. 1996. Interim Management Guidelines for Howell's lousewort (Pedicularis howellii Gray). Unpublished manuscript.