Montana Field Guide

Slender Fleabane is a perennial with 1-few stems that are 3-15 cm tall, arising from a taproot and woody rootcrown. Foliage is covered by short hairs. The basal leaves have a pointed leaf blade 7-25 mm long tapering at the base to the leaf stalk. Stem leaves are linear and few. The daisy-like, flowering heads are 1-3 on the stem. Involucral bracts are 3.5 mm long, finely glandular, and usually with short, spreading hairs. The 15-40 rays are blue or sometimes purple, 4-8 mm long and 1-1.7 mm wide. The achenes have 15-30 inner bristles about as long as the disk corollas, and outer bristles are obscure or wanting.

Flowering in late July - early August.

A combination of the woody rootcrown, single-veined basal leaves, reduced stem leaves, absence of spreading stem hairs, blue rays, and leaf shape distinguish it from most western Erigeron in our area including E. tweedyi and E. cespitosus. A hand lens or microscope and technical key are needed for positive identification.

Open limestone slopes in the upper montane zone.

POLLINATORS
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus bifarius, Bombus centralis, Bombus fervidus, Bombus flavifrons, Bombus huntii, Bombus melanopygus, Bombus mixtus, Bombus rufocinctus, Bombus occidentalis, and Bombus insularis (Thorp et al. 1983, Wilson et al. 2010, Colla and Dumesh 2010, Koch et al. 2012).

STATE THREAT SCORE REASON
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).