Montana Field Guide

Plants: Annuals with a fibrous root system and up to several stems. Stems erect to prostrate with ascending tips, 10-70 cm in length (Douglas et al. 1999); herbage villous to hirsute (Lesica 2012), densely so on the bottom of the involucre and top of the peduncle (Barneby 1989).

Leaves: Palmately compound, alternate (Douglas et al. 1999); leaflets 3, 5-16 mm in length, 2.5-9 mm in width (Barneby 1989), obovate, the margins serrate distally; stipules 5–10 mm long, lanceolate, adnate to the petiole (Lesica 2012), the margins smooth to shallowly toothed (Barneby 1989), occasionally with a bristle tip (Douglas et al. 1999); petioles usually 1-4.5 cm in length, although the far distal ones may be shorter (Barneby 1989).

Inflorescences: Racemes axillary, 5–10 mm long, longer than the leaves, subtended by a villous, saucer-shaped involucre of partially fused bracts (Lesica 2012); involucre 5-12 mm across, split about halfway into 5-11 lobes; lobes entire to 3-toothed (Barneby 1989), papery, bristle-tipped and typically untoothed (Douglas et al. 1999); heads a half-sphere becoming ovoid, each with about 7-40 flowers (Barneby 1989).

(Lesica’s contribution adapted from Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)

Flowering June-August (Barneby 1989).

Resembles White-tip Clover (T. variegatum) in structure, habit, and flower-head size, and is associated with it in wet meadows. However, Woolly Clover has long, soft hairs nearly all over, thickly so at the uppermost part of the peduncle and bottom of the involucre, and usually just a single seed. White-tip Clover is glabrous and usually 2 seeded (Barneby 1989).

Moist meadows (Barneby 1989), sandy banks along rivers to dry hillsides (Hitchcock et al. 1961).

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).

Flowers: Flowers white to pink, 4–5 mm long; calyx villous basally, 3-5 mm in length, nearly as long as the corolla (Lesica 2012), the tube with 10 ribs and 1.6-2.3 mm in length, the teeth triangular and spine-tipped, entire and ca 1.5-3 mm in length (Barneby 1989).

Fruit: Legume obovoid to oval, 1.5-2 mm in length, the valves weakly networked with ridges or slightly gritty distally, enclosing 1 (Barneby 1989) or 2 seeds (Lesica 2012).

(Lesica’s contribution adapted from Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)

STATE THREAT SCORE REASON
Reported threats to Montana's populations of Woolly Clover include threats due to exotic species and associated risks from herbicide application (MTNHP Threat Assessment 2021). Common St. John's-wort (Hypericum perforatum), Leafy Spurge (Euphorbia virgata), Spotted Knapweed (Centaurea stoebe), and exotic grasses occur with some populations. Chemical herbicide is applied to control co-occurring noxious species and likely inflicts additional stress at these populations.