Dioecious. Plants 9-30 cm (stems stipitate-glandular distally). Stolons 1-5 cm. Basal leaves 1-nerved, spatulate, 6-16 × 2-6 mm, tips mucronate, faces silvery gray-pubescent. Cauline leaves linear, 5-25 mm, not flagged (apices acute). Heads 6-13 in corymbiform arrays. Involucres: staminate 5-6.5 mm; pistillate 5.5-7 mm. Phyllaries distally bright white to light yellow. Corollas: staminate 2.5-3 mm; pistillate 3-4.3 mm. Cypselae 0.7-1.2 mm, glabrous or sparingly papillate; pappi: staminate 3-4 mm; pistillate 3-5 mm. 2n = 28.
Flowering early-mid summer. Moist open areas, flood plains of streams, margins of alkaline depressions, lower montane to subalpine (subarctic); 0-3200 m; Alta., B.C., Man., N.W.T., Nunavut, Ont., Que., Sask., Yukon; Alaska, Ariz., Calif., Colo., Idaho, Minn., Mont., Nebr., Nev., N.Mex., N.Dak., Oreg., S.Dak., Utah, Wash., Wyo.
Antennaria microphylla is a primary sexual progenitor of the A. rosea polyploid agamic complex (R. J. Bayer 1990b). A. Cronquist (1955) included A. rosea within his circumscription of A. microphylla. It is preferable to recognize sexual diploids as distinct from their morphologically discrete hybrid apomictic derivatives. Antennariamicrophylla is always dioecious and has stems distally stipitate-glandular and white phyllaries; A. rosea is always gynoecious and has stems without glandular hairs and phyllaries only occasionally white.
Some authors (A. E. Porsild 1950; E. H. Moss 1959; Porsild and W. J. Cody 1980) have recognized A. nitida as distinct; comparisons of the nomenclatural types of the two show that they are conspecific. Antennaria microphylla has allelopathic properties (G. D. Manners and D. S. Galitz 1985).
Mat-forming, stoloniferous, 5-40 cm; herbage closely and persistently gray-tomentose, or some of the lvs rarely finally glabrate above; basal lvs oblanceolate or spatulate, 8-30 נ2-7 mm; heads several in a subcapitate or rather loose cyme; pistillate invols 4-7 mm, the scarious part of the bracts deep pink to bright white or dull whitish, generally appearing striate at 20 dry pistillate cors 2.5-4.5 mm; sexual or apomictic; 2n=28, 56. Dry, open places, meadows, and open woods; chiefly in the w. cordillera, e. to w. Minn., w. Ont., and n. Mich. May-Aug. (A. rosea) The name A. microphylla may eventually have to give way to the older A. chilensis Remy, from Chilean Patagonia.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.