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Grindelia howellii Steyermark

Howell's Gumweed

Asteraceae (Aster family)

General Description: Howell's gumweed is a stout, short-lived perennial with upright stems 30-90 cm tall clustered on a taproot. The glandular herbage usually has some additional long, soft hairs, especially on upper portions of the stem. Leaves are rough and relatively thin; those at the base are lance-shaped and up to 20 cm long. The clasping stem leaves are smaller, with entire, dentate or denticulate margins. One to several flower heads are borne in a terminal, open inflorescence. Heads are radiate with bright yellow rays about 1 cm long. The surrounding spherical-shaped involucres are comprised of numerous, narrow, very sticky bracts that have pronounced recurved tips.

Illustration.

Field Identification Tips: The bright yellow flower heads are easily seen in the field. These heads are subtended by sticky, recurved involucral bracts. Plants are distinguished by their glandular stems which also have some long, soft hairs, at least in the upper branches and inflorescence area. In addition, the stem leaves are wide at the base and clasping.

Photo © Christine Lorain CLICK PHOTO FOR A LARGER IMAGE

Phenology: Flowering from mid-July to late August.

Similar Species: Grindellia squarrosa and G. nana are two similar-looking species occurring within the range of Howell's gumweed. They both have essentially glabrous stems, as opposed to the strongly glandular and resinous foliage of G. howellii.

Habitat: The few known Idaho populations occur in an area of open, grassy, southerly-facing bluffs surrounded by mixed conifer forests. In Montana, populations occur in a variety of natural and disturbed habitats, especially the latter. These roadside, pasture, forest opening, and grassland populations are located along the transition zone between lower elevation grassland and intermixed lower forest areas. Grindelia howellii does not tolerate closed canopy shade and is apparently adapted to early successional, disturbed areas.

Global Distribution: Howell's gumweed is a regional endemic with two disjunct population centers located about 150 miles apart in northern Idaho and western Montana. The majority of known populations are in Montana, within Missoula and Powell counties.

Photo © Christine Lorain CLICK PHOTO FOR A LARGER IMAGE

Idaho Distribution: Known from bluffs above the St. Maries River in Benewah County.

References:

Lorain, C. C. 1991. Species management guide for Grindellia howellii (Howell's gumweed), on the St. Joe National Forest. Unpublished report prepared for the Panhandle National Forests by the Idaho Department of Fish and Game, Conservation Data Center, Boise. 17 pp. plus appendices.

Lorain (Ebrahimi), C. 1991. Rare plants on the Idaho Panhandle National Forests. Unpublished pamphlet prepared for the U.S. Department of Agriculture, Idaho Panhandle National Forests, Coeur d'Alene, ID. 49 pp.

Montana Natural Heritage Program. Montana rare plant field guide. Available at: http://nhp.nris.state.mt.us.

Shelly, J. S. 1989. Report on the conservation status of Grindellia howellii, a candidate threatened species. Unpublished report prepared by the Montana Natural Heritage Program, Helena, MT. 139 pp.