Montana Field Guide

Dense-leaved Antennaria is a low, mat-forming perennial with stems which are 2-6 cm high and which spread by prostrate runners from a branched rootcrown clothed in old leaf bases. The broadly spoon-shaped basal leaves are 3-6 mm long, while the alternate stem leaves are shorter and narrowly lance-shaped with small, curled tips. The foliage is densely covered with long white hairs. 2-5 flower heads are borne atop the stems, and male and female flowers are borne on different plants. Female flower heads have 3-4 series of overlapping, narrowly lance-shaped involucral bracts which are 4-5 mm long with brownish, papery tips, in addition to having white disk flowers which are ca. 3 mm long. Ray flowers are lacking. Male heads are slightly broader with shorter involucral bracts. The seed has long, stiff bristles at the top.

Flowering primarily in July.

There are many species of small-leaved, mat-forming Antennaria. Only 2 other species have papery tips of involucral bracts that are brownish: A. umbrinella has longer, more lance-shaped leaves, and A. aromatica has foliage with glandular hairs and basal leaves that are usually greater than 6 mm long. A hand lens is necessary to discern the diagnostic characters.

Gravelly, (limestone), gently-sloping, alpine tundra.

POLLINATORS
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus pensylvanicus (Colla and Dumesh 2010).

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