OregonFlora: Astragalus beckwithii vs. Astragalus arthuri

	Astragalus beckwithii	Astragalus arthuri
	Weiser's milkvetch	Arthur's milkvetch, Waha milkvetch
Habit		Plants perennial, subacaulescent to caulescent, strigillose, hairs basifixed.
Stems		several, ascending to erect, forming bushy clumps, 2–40 cm.
Leaves		4–14 cm; leaflets (15)19–27, linear-elliptic; oval or oblanceolate, 2–20 × 2–4 mm; tips obtuse to subacute, truncate-mucronulate or shallowly retuse; surfaces abaxially strigillose, adaxially glabrous; stipules 2–7 mm; free.
Inflorescences		racemes loosely (5)8–20-flowered; peduncles (7)10–20 cm; bracts 1.5–3.5 mm; pedicels 1–4 mm; bracteoles usually 0.
Flowers		declined at anthesis; calyces 6.6–8.8 mm, strigose with mixed black and white hairs; tubes 4.5–6 mm; teeth lance-subulate 1.8–3.5 mm; corollas 11.7–15.2 mm, ochroleucous; ovules 16–30.
Fruits		bilocular, pendulous, linear-ellipsoid, compressed-triquetrous, tapering distally into a slender acuminate beak, nearly straight or gently incurved, deeply sulcate; (25)30–40 × 2.5–4 mm, strigillose; valves papery; stipes 6–15 mm.
2n		=24.

	Astragalus beckwithii	Astragalus arthuri
Distribution	[WildflowerSearch map] [BONAP county map]
Discussion		Open coniferous forests, grassland slopes, meadows. Flowering May–Jul. 400–1400 m. BW. ID, WA. Native. Early flowering plants appear subacaulescent as the leaves are in loose basal tufts, and the peduncles appear subscapose. Later in the season, the plants are more obviously caulescent, but even then the peduncles and racemes are longer than the stems. This feature plus the long slender linear pods help distinguish this species.
Source		Flora of Oregon, volume 2, page 658 Richard Halse
Sibling taxa	A. accidens, A. agrestis, A. alpinus, A. alvordensis, A. applegatei, A. arthuri, A. atratus, A. australis, A. californicus, A. calycosus, A. canadensis, A. caricinus, A. collinus, A. conjunctus, A. curvicarpus, A. cusickii, A. diaphanus, A. drummondii, A. eremiticus, A. filipes, A. gambellianus, A. geyeri, A. hoodianus, A. howellii, A. inflexus, A. iodanthus, A. kentrophyta, A. lemmonii, A. lentiginosus, A. malacus, A. misellus, A. mulfordiae, A. multiflorus, A. newberryi, A. nudisiliquus, A. obscurus, A. peckii, A. platytropis, A. purshii, A. reventus, A. robbinsii, A. salmonis, A. sclerocarpus, A. sheldonii, A. solitarius, A. spaldingii, A. sterilis, A. succumbens, A. tegetarioides, A. tetrapterus, A. toanus, A. tweedyi, A. tyghensis, A. umbraticus, A. vallaris, A. whitneyi	A. accidens, A. agrestis, A. alpinus, A. alvordensis, A. applegatei, A. atratus, A. australis, A. beckwithii, A. californicus, A. calycosus, A. canadensis, A. caricinus, A. collinus, A. conjunctus, A. curvicarpus, A. cusickii, A. diaphanus, A. drummondii, A. eremiticus, A. filipes, A. gambellianus, A. geyeri, A. hoodianus, A. howellii, A. inflexus, A. iodanthus, A. kentrophyta, A. lemmonii, A. lentiginosus, A. malacus, A. misellus, A. mulfordiae, A. multiflorus, A. newberryi, A. nudisiliquus, A. obscurus, A. peckii, A. platytropis, A. purshii, A. reventus, A. robbinsii, A. salmonis, A. sclerocarpus, A. sheldonii, A. solitarius, A. spaldingii, A. sterilis, A. succumbens, A. tegetarioides, A. tetrapterus, A. toanus, A. tweedyi, A. tyghensis, A. umbraticus, A. vallaris, A. whitneyi
Subordinate taxa	A. beckwithii var. weiserensis
Web links	Local floras: BC, OR, WA Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: OR, WA Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Astragalus arthuri

Weiser's milkvetch

Arthur's milkvetch, Waha milkvetch

Habit

Plants perennial, subacaulescent to caulescent, strigillose, hairs basifixed.

Stems

several, ascending to erect, forming bushy clumps, 2–40 cm.

Leaves

4–14 cm;

leaflets (15)19–27, linear-elliptic; oval or oblanceolate, 2–20 × 2–4 mm;

tips obtuse to subacute, truncate-mucronulate or shallowly retuse;

surfaces abaxially strigillose, adaxially glabrous;

stipules 2–7 mm; free.

Inflorescences

racemes loosely (5)8–20-flowered;

peduncles (7)10–20 cm;

bracts 1.5–3.5 mm;

pedicels 1–4 mm;

bracteoles usually 0.

Flowers

declined at anthesis;

calyces 6.6–8.8 mm, strigose with mixed black and white hairs;

tubes 4.5–6 mm;

teeth lance-subulate 1.8–3.5 mm;

corollas 11.7–15.2 mm, ochroleucous;

ovules 16–30.

Fruits

bilocular, pendulous, linear-ellipsoid, compressed-triquetrous, tapering distally into a slender acuminate beak, nearly straight or gently incurved, deeply sulcate; (25)30–40 × 2.5–4 mm, strigillose;

valves papery;

stipes 6–15 mm.

=24.

Astragalus arthuri

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Open coniferous forests, grassland slopes, meadows. Flowering May–Jul. 400–1400 m. BW. ID, WA. Native.

Early flowering plants appear subacaulescent as the leaves are in loose basal tufts, and the peduncles appear subscapose. Later in the season, the plants are more obviously caulescent, but even then the peduncles and racemes are longer than the stems. This feature plus the long slender linear pods help distinguish this species.

Source

Flora of Oregon, volume 2, page 658
Richard Halse

Sibling taxa