Montana Field Guide

Woolly-head Clover is a perennial with erect stems that are 20-60 cm tall and arising from a thick taproot and a branched rootcrown. The leaves have three leaflets that are 2-7 cm long and elliptic to oblong with sharply toothed margins. The base of each leaf petiole is enlarged to form two lance-shaped wings, or stipules, that are 2-5 cm long. The foliage is sparsely to densely long-hairy. 25-80 flowers are borne in globose clusters at the ends of the main stem or on side branches. The pinkish to red flowers are nodding and 12-17 mm long with a hood-shaped upper petal, or banner, as well as two narrow, separate petals on the side (wings); the two lower petals are united into a boat-shaped petal, or keel. The calyx has five long teeth at the mouth and is covered with long, feather-like hairs. The fruit is a small pod with 4 ovules.

Ours is subspecies arcuatum McDermott. There are many species of clover in Montana, and a technical key should be consulted for positive identification. This species can be distinguished from other perennial species of Trifolium occurring at lower elevations by the combination of having an erect, leafy habit, lacking a leafy involucre below the inflorescence, and by its long feathery hairs on the calyx teeth.

Dry meadows, woods and margins in the foothill and lower montane zones.

POLLINATORS
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus vagans, Bombus appositus, Bombus auricomus, Bombus bifarius, Bombus borealis, Bombus centralis, Bombus fervidus, Bombus flavifrons, Bombus frigidus, Bombus huntii, Bombus melanopygus, Bombus mixtus, Bombus nevadensis, Bombus rufocinctus, Bombus sylvicola, Bombus ternarius, Bombus occidentalis, Bombus pensylvanicus, Bombus bimaculatus, Bombus griseocollis, Bombus impatiens, Bombus insularis, Bombus suckleyi, Bombus bohemicus, Bombus flavidus, and Bombus kirbiellus (Plath 1934, Hobbs 1966, Macior 1974, Heinrich 1976, Bauer 1983, Thorp et al. 1983, Mayer et al. 2000, Rao and Stephen 2007, Wilson et al. 2010, Colla and Dumesh 2010, Colla et al. 2011, Koch and Strange 2012, Koch et al. 2012, Miller-Struttmann and Galen 2014, Williams et al. 2014).

STATE THREAT SCORE REASON
Reported threats to Montana's populations of Woolly-head Clover include impacts due to noxious weeds, and potential impacts from firewood gathering and recreation activity (MTNHP Threat Assessment 2021). Spotted Knapweed (Centaurea stoebe) occurs with low density at some populations with slight negative impacts. Noxious weed populations have potential to expand with greater negative impacts following ground disturbances that expose bare soil, such as firewood gathering and recreation activity. Information about the scope, severity, and timing of impacts from firewood gathering and/or recreational activities is needed to assess their contribution to impacts.