Astragalus missouriensis var. amphibolus
Mancos milkvetch, Missouri milkvetch
to 10 cm.
4–8-flowered.
calyx 8.5–13 mm, tube 7–10 mm, lobes 1.5–3 mm;
corolla usually pink-purple, rarely white;
banner (14.5–)16–22(–24) mm;
keel (11.5–)12.8–17.3(–18.5) mm.
sometimes deciduous, ascending to descending, dorsiventrally compressed, lunately incurved, ellipsoid, (11–)15–25 × 7–9 mm, unilocular, apex obcompressed proximal to incurved beak, strigose.
35–55.
Astragalus missouriensis var. amphibolus
The fruits of var. amphibolus are initially dorsiventrally compressed, and ultimately dehisce apically while still attached to the inflorescence (though sometimes deciduous). The fruits have a lateral ridge down each valve, with the valves separated by more or less prominent bicarinate keels. In these features, along with the typically persistent fruits, the plants can be distinguished from the similar Astragalus amphioxys var. amphioxys where their ranges are contiguous, as in northwestern New Mexico and vicinity. R. C. Barneby (1947b, 1964) suggested that hybridization occurs between the two taxa.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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