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Montana Field Guide

Montana Field Guides

Woolly-head Clover - Trifolium eriocephalum

Species of Concern
Native Species

Global Rank: G5
State Rank: S2
(see State Rank Reason below)

Agency Status
MNPS Threat Rank: 2
C-value: 4

External Links

State Rank Reason (see State Rank above)
Known from eight large occurrences on the Bitterroot National Forest. Invasive weeds, particularly spotted knapweed, are a problem in the habitat occupied by the species. Timber harvest and related road-building activities may also negatively impact populations. However, Trifolium eriocephalum appears capable of tolerating some level of disturbance.
General Description
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.

Diagnostic Characteristics
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.

Species Range

Range Comments
WA to MT south to CA, NV and UT (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 30

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

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

Ecological Systems Associated with this Species

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Citation for data on this website:
Woolly-head Clover — Trifolium eriocephalum.  Montana Field Guide.  .  Retrieved on , from