Astragalus missouriensis var. amphibolus |
Astragalus missouriensis var. missouriensis |
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Mancos milkvetch, Missouri milkvetch |
Missouri milk-vetch |
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Habit | Plants subacaulescent to shortly caulescent. | Plants usually shortly caulescent, sometimes subacaulescent. |
Stems | to 10 cm. |
to 15 cm. |
Racemes | 4–8-flowered. |
(3–)5–15-flowered. |
Flowers | 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. |
calyx 9–12(–14.3) mm, tube 6.3–9(–9.3) mm, lobes 1.4–4.5(–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. |
Legumes | sometimes deciduous, ascending to descending, dorsiventrally compressed, lunately incurved, ellipsoid, (11–)15–25 × 7–9 mm, unilocular, apex obcompressed proximal to incurved beak, strigose. |
ascending, initially subterete or ± dorsiventrally compressed, ± straight, subsymmetrically oblong-ellipsoid, ± laterally compressed and obtuse-angled when mature, 15–28(–30) × (4–)5–9(–10) mm, subunilocular, base obtuse or sometimes cuneate, apex abruptly contracted into subulate, pungent beak, sutures prominent, strigulose. |
Seeds | 35–55. |
(33–)40–50(–56). |
2n | = 22. |
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Astragalus missouriensis var. amphibolus |
Astragalus missouriensis var. missouriensis |
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Phenology | Flowering May–Jul. | Flowering late Mar–Jul. |
Habitat | Pinyon-juniper and sagebrush communities, on igneous or sandstone outcrops or substrates. | Prairies, valleys, hillsides, dry open places, on limestone, shale, sandstone, or gypsum substrates. |
Elevation | 1600–2500 m. (5200–8200 ft.) | 300–2400 m. (1000–7900 ft.) |
Distribution |
AZ; CO; NM; UT |
AZ; CO; IA; KS; MN; MT; ND; NE; NM; OK; SD; TX; WY; AB; MB; SK |
Discussion | 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.) |
There is an irregular cline in flower size of var. missouriensis, from smallest in the north to largest in the south; caulescent forms appear to be more common southward (D. Isely 1998). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 11. | FNA vol. 11. |
Parent taxa | ||
Sibling taxa | ||
Name authority | Barneby: Amer. Midl. Naturalist 37: 447. (1947) | unknown |
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