Flora of North America species comparison

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Astragalus amphioxys var. amphioxys

Astragalus sect. Argophylli
Photo is of parent taxon

crescent milkvetch
Habit Herbs perennial (sometimes flowering as annual), usually tuft- or mat-forming, acaulescent, subacaulescent, or caulescent; caudex usually superficial or aerial, sometimes subterranean.
Stems

(when present) obsolete, single, few, or several to many.
Leaves

odd-pinnate, usually petiolate, rarely short-petiolate or subsessile;

leaflets (1 or)3–39(–43).
Racemes

subcapitate to loosely flowered, flowers erect, ascending, spreading, declined, or nodding, secund, and retrorsely imbricate.
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.

Corollas

purple, pink-purple, magenta-purple, violet, bluish, lilac, scarlet, ochroleucous, greenish white, or white, banner barely recurved (A. phoenix) or recurved through 20–50° (90–100° in A. accumbens), keel apex obtuse.
Calyx

tubes cylindric or deeply campanulate.
Legumes

15–40 mm, curved.

usually deciduous, usually sessile, rarely subsessile or substipitate, gynophore sometimes present, usually ascending (humistrate), less often spreading or pendulous, subglobose to ellipsoid, narrowly lanceoloid, ovoid or oblong-ellipsoid, or lanceoloid-ovoid, straight or usually incurved, usually compressed dorsiventrally, sometimes obcompressed, 3-sided, turgid, or inflated, unilocular, subunilocular, or bilocular.
Seeds

(42–)44–56.

11–70.
Hairs

basifixed or malpighian.
Stipules

distinct (except anomalous forms of A. missouriensis, A. tephrodes, and A. zionis).
2n

= 22.

Astragalus amphioxys var. amphioxys

Astragalus sect. Argophylli
Phenology Flowering late Mar–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.
Elevation 400–2100 m. (1300–6900 ft.)
Distribution
from FNA
AZ; CO; NM; NV; TX; UT; Mexico (Chihuahua)
[BONAP county map]
w North America; n Mexico
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.)

Species 44 (44 in the flora).

Section Argophylli comprises ten subsections, widespread in western North America from southern British Columbia and Saskatchewan southward to northern Baja California, northern Sonora, and western Texas.

The subsections are: subsect. Argophylli (A. Gray) M. E. Jones (Astragalus argophyllus, A. callithrix, A. columbianus, A. cyaneus, A. desereticus, A. eurylobus, A. henrimontanensis, A. iodopetalus, A. piutensis, A. shortianus, A. tephrodes, A. tidestromii, A. uncialis, A. zionis); subsect. Pseudargophylli Barneby (A. feensis, A. waterfallii); subsect. Neomexicani Barneby (A. neomexicanus); subsect. Newberryani M. E. Jones (A. eurekensis, A. loanus, A. musiniensis, A. newberryi, A. phoenix, A. welshii); subsect. Concordi S. L. Welsh (A. concordius); subsect. Coccinei M. E. Jones (A. coccineus); subsect. Eriocarpi (A. Gray) Barneby (A. anserinus, A. funereus, A. inflexus, A. leucolobus, A. nudisiliquus, A. purshii, A. subvestitus, A. utahensis); subsect. Parryani Barneby (A. parryi); subsect. Missourienses M. E. Jones (A. accumbens, A. amphioxys, A. castaneiformis, A. chamaeleuce, A. consobrinus, A. cymboides, A. laccoliticus, A. missouriensis, A. piscator); and subsect. Anisi Barneby (A. anisus).

(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
Sibling taxa
A. amphioxys var. modestus, A. amphioxys var. musimonum, A. amphioxys var. vespertinus
Subordinate taxa
Name authority unknown A. Gray: Proc. Amer. Acad. Arts 6: 209. (1864)
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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