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Antennaria media ranges from Arizona to Alaska; dioecious and gynoecious populations are encountered (R. J. Bayer and G. L. Stebbins 1987). The dioecious (sexual) populations are restricted primarily to California and Oregon (Bayer et al. 1990). The main distinction between A. media and A. alpina is flags on distal cauline leaves present in A. alpina and mostly absent in A. media (Bayer 1990d). Phyllaries of the pistillate plants in A. alpina tend to be acute; they are blunter in A. media. At some point, it may be preferable to follow W. L. Jepson ([1923–1925]) and some later authors and treat A. media as a subspecies of A. alpina. Antennaria media appears to be an autopolyploid derivative of A. pulchella; genes from A. pulchella may have introgressed into the A. alpina and A. parvifolia complexes indirectly through A. media.
Antennaria media is a species of flowering plant in the daisy family known by the common name Rocky Mountain pussytoes. It is native to western North America from Alaska and northwestern Canada to California to New Mexico, where it grows in cold regions such as the alpine climate of high mountains. This is a perennial herb forming a matted patch of stolons and woolly basal leaves with flower clusters no more than about 13 centimeters tall. The flower clusters contain several flower heads. The species is dioecious, with male and female plants producing flower heads of slightly different morphologies. The fruit is an achene up to about 6 millimeters long, most of which is the long, soft pappus. There are several subspecies; one subspecies is diploid and reproduces sexually and the others are polyploid and display apomixis. Identifying features of antennaria media include the clustered flowerheads (rather than single), the small grey-hairy leaves with just one, central vein, and the dark brown phyllaries. Plants form low mats, spreading via short (less than 2 inches) stolons. Leaves grow at the base and along the erect stems; they are relatively thick, and have a sharp point at the apex. Both surfaces are evenly covered by appressed greyish hairs. Basal leaves are wider towards the top; stem leaves are narrower, equal in length and more linear in shape.
Antennaria compacta was included in A. alpina s.l. by Bayer in Cody (1996) and in Bayer (2006), who stated that morphological overlap between A. alpina and A. media poses a taxonomic problem. Bayer (2006) suggests that some of the entities he has synonymised under A. alpina, including A. friesiana subsp. compacta, are of apomictic clonal origin. This subspecies was included in A. media s.l. by Chmielewski (1997). Elven et al. (2003) followed Chmielewski (1997) by recognising this taxon as a subspecies of A. media because Chmielewski (1998) presented an analysis that included the A. alpina complex. Elven et al. (2003) will follow this treatment until a consensus is reached about A. alpina in North America and we follow this treatment here. Illustrations. • Two species in same habitat: Dorset. Left of the marker, plants with inflorescences that have more than one head per flowering stem are A. media subsp. compacta. Right of the marker, inflorescences with a single head per flowering stem are A. monocephala subsp. angustata. Nunavut, Baffin Island, Cape Dorset. Aiken. 4 August, 2005. Scale bar in cm. • Arctic Island Distribution. (Source: nature.ca)