Flora of North America species comparison

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Astragalus amphioxys var. amphioxys

Astragalus amphioxys var. vespertinus
Photo is of parent taxon

crescent milkvetch
Photo is of parent taxon

aladdin's slippers, evening milkvetch
Flowers

calyx cylindric, tube (5.8–)7–10.5 mm, lobes 1.5–3.7(–4.5) mm;

corolla banner (16.2–)19–24.5 mm;

keel (13.2–)14.3–18.8(–19.6) mm.

calyx cylindric, tube 8.8–13.2 mm, lobes 1.3–3 mm;

corolla banner 23–27(–28) mm;

keel 19–23.6 mm.
Legumes

15–40 mm, curved.

30–35 mm, gently incurved.
Seeds

(42–)44–56.

50–70.
2n

= 22.

Astragalus amphioxys var. amphioxys

Astragalus amphioxys var. vespertinus
Phenology Flowering late Mar–Jun. Flowering Apr–Jun.
Habitat Sandy valleys, plains, gravelly hillsides, on dunes, rarely on gumbo-clay flats, in creosote bush, Joshua tree, blackbrush, indigo bush, salt desert shrub, pinyon-juniper, and mountain brush communities. Sandy valley floors, ledges under cliffs, gravelly hillsides, in sagebrush or mountain brush communities, pinyon-juniper forests, usually on sandstone.
Elevation 400–2100 m. (1300–6900 ft.) 600–1800(–2000) m. (2000–5900(–6600) ft.)
Distribution
from FNA
AZ; CO; NM; NV; TX; UT; Mexico (Chihuahua)
[BONAP county map]
from FNA
AZ; CO; NM; UT
[BONAP county map]
Discussion

Variety amphioxys is variable and includes elements that may be taxonomically significant (D. Isely 1998).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Variety vespertinus is found locally within the Colorado Basin and occurs from northwestern New Mexico to southwestern Colorado, through southeastern Utah, extending to the Grand Canyon and Kanab Plateau of northwestern Arizona. It is a large-flowered, more or less northern form of the species that is, otherwise, poorly characterized.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Astragalus > sect. Argophylli > Astragalus amphioxys Fabaceae > subfam. Faboideae > Astragalus > sect. Argophylli > Astragalus amphioxys
Sibling taxa
A. amphioxys var. modestus, A. amphioxys var. musimonum, A. amphioxys var. vespertinus
A. amphioxys var. amphioxys, A. amphioxys var. modestus, A. amphioxys var. musimonum
Synonyms A. vespertinus
Name authority unknown (E. Sheldon) M. E. Jones: Rev. N.-Amer. Astragalus, 215. (1923)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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