Montana Field Guide

PLANTS: A short, perennial forb that grows from a well branched caudex atop of a tap root. Plants are 5-40 cm and grow prostrate to ascending to erect with showy flowers and an inflated, round seed pod.

LEAVES: Pinnately dissected, with 13-21 leaflets which are oblanceolate to linear. Leaflets have (basifixed) hairs which make the plant appear slightly grayish. The leaf sheaths (stipules) are 3-8 mm long, lanceolate, and not fused around the stem. The leaves are usually taller and surpass the inflorescence.

INFLORESCENCE: A subcapitate to loose raceme arising from leaf axils with 5-20 flowers. Flowers are long, 22-30 mm, and either predominately purple or white with purple-tips. The banner petal is 22–30 mm long and moderately reflexed. The keel petal is 14–20 mm long. Sepals are 2-4 mm longs with black and/or white strigose hairs.

Montana plants are of variety crassicarpus or paysonii.

Sources: Lesica et al. 2012; Dorn 2001; and Flora of the Great Plains 1986.

In Montana Astragalus crassicarpus has two varieties (Lesica et al. 2012):

* var. paysonis has predominately white flowers (petals) with purple tips. It is mostly found in the western half of Montana.

* var. crassicarpus has predominately purple flowers (petals). It is found on the Great Plains.

POLLINATORS
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus vagans, Bombus appositus, Bombus auricomus, Bombus bifarius, Bombus borealis, Bombus centralis, Bombus fervidus, Bombus flavifrons, Bombus huntii, Bombus mixtus, Bombus nevadensis, Bombus rufocinctus, Bombus ternarius, Bombus terricola, Bombus occidentalis, Bombus pensylvanicus, Bombus griseocollis, and Bombus insularis (Macior 1974, Thorp et al. 1983, Mayer et al. 2000, Colla and Dumesh 2010, Wilson et al. 2010, Koch et al. 2012, Miller-Struttmann and Galen 2014, Williams et al. 2014).

FRUITS
The ovary and legume are glabrous, and grow on short petioles. Legumes are 13-20 mm long, become inflated and nearly round (globose), possess a short narrow beak, and have 2 chambers. Legumes are fleshy inside, becoming leathery with age. Fruits generally lay on the ground at maturity.

Sources: Lesica et al. 2012; Dorn 2001; and Flora of the Great Plains 1986.