Montana Field Guide

Perennial with a branched caudex clothed in old leaf bases. Stems prostrate to ascending, sericeous, 3–10 cm. Leaf blades cordate-ovate, pinnately divided into 5 to 7 pinnately toothed leaflets, 5–15 mm long, sparsely to densely sericeous above, white-tomentose beneath. Inflorescence a few-flowered, sericeous cyme with spreading branches. Flowers: sepals broadly lanceolate, 4–7 mm long with narrower bracteoles 3–5 mm long; petals yellow, 5–8 mm long, truncate. Achenes smooth, about 2 mm long (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Flowering in early summer (FNA 2014).

Barry Johnston in his 1980 monograph of Potentilla section Multijugae supports recognition of this taxon at the specific level, in a section different from that of P. concinna. This he based on characters of style shape and texture and leaf lobing pattern. However, this monograph is a Doctoral thesis so did not undergo the same peer-review process that a published article would.

The Potentilla treatment by authors Ertter, Elven, Reveal, and Murray in Flora of North America, Volume 9 (2014) accepted Potentilla macounii as a distinct species in Section Concinnae based on a combination of characteristics: subpinnate leaves where at least two proximal pairs of leaflets well separated from the terminal leaflets and plants having somewhat softer hairs.

Potentilla macounii has at least 2 leaflets on the petiole that are well separated from the terminal leaflets plus the inflorescence has 1-5 flowers, stipules are entire or shallowly lobed, bracteoles are shorter than sepals, petals are longer than sepals, and style is at least 2 mm long. In Potentilla concinna leaflets are attached at the tip of the petiole (Lesica et al. 2012). In Potentilla pensylvanica the stipules are deeply lobed, bracteoles are equal or longer than the sepals, and the styles are 1.2 mm or less. In Potentilla hippiana the inflorescence usually has more than 5 flowers and the petals and sepals are similar in length. In Potentilla rubicaulis the inflorescence usually has 1-5 flowers, but the styles are about 1 mm long.

Sandy to gravelly, shallow, often calcareous soil of grasslands, woodlands, outcrops; valleys, montane (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

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 fervidus, Bombus frigidus, Bombus rufocinctus, Bombus occidentalis, Bombus pensylvanicus, Bombus impatiens, and Bombus flavidus (Thorp et al. 1983, Wilson et al. 2010, Colla and Dumesh 2010, Colla et al. 2011, Koch and Strange 2012, Koch et al. 2012, Williams et al. 2014).