OregonFlora: Astragalus beckwithii vs. Astragalus tweedyi

	Astragalus beckwithii	Astragalus tweedyi
	Weiser's milkvetch	Tweedy's milkvetch
Habit		Plants perennial, caulescent, loosely strigillose to villosulous, hairs basifixed.
Stems		few, ascending to erect, 20–80 cm.
Leaves		3–10(13) cm; leaflets (7)11–23, narrowly oblong-oblanceolate to linear-oblong, 5–22(25) × 1–2 mm; tips retuse to obtuse; surfaces abaxially strigillose, adaxially strigillose to glabrous; stipules 1–7 mm; free.
Inflorescences		racemes dense but elongating and becoming looser, 10–35(50)-flowered; peduncles (5)7–15 cm; bracts 1.5–6 mm; pedicels 0.8–2.5 mm; bracteoles 0.
Flowers		erect to spreading at anthesis; calyces gibbous-convex at bases, 8–10.5 mm, villous or villous-tomentulose with mostly white hairs; tubes 7.5–9 mm; teeth triangular, 1–2.1 mm; corollas 15–18.6 mm, ochroleucous, unspotted; ovules 12–19.
Fruits		unilocular; erect, oblong-ellipsoid; straight or slightly arcuate, laterally compressed, bicarinate, 12–15 × 3–4(5.4) mm, rugulose, sparsely pilosulose or glabrous; valves coriaceous; stipes 6–10 mm.

	Astragalus beckwithii	Astragalus tweedyi
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion		Dry hillsides, ridges, roadside banks, sagebrush. Flowering May–Jul. 100–1000 m. Col. WA. Native. In Oregon, there are three species of Astragalus that have calyces that are obviously gibbous at the base so that the pedicel is attached obliquely: A. tweedyi, A. collinus, and A. curvicarpus; the three species are closely related. Astragalus tweedyi can be distinguished by its erect fruits, while the other species have pendulous fruits.
Source		Flora of Oregon, volume 2, page 675 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. arthuri, 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. 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) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Astragalus tweedyi

Weiser's milkvetch

Tweedy's milkvetch

Habit

Plants perennial, caulescent, loosely strigillose to villosulous, hairs basifixed.

Stems

few, ascending to erect, 20–80 cm.

Leaves

3–10(13) cm;

leaflets (7)11–23, narrowly oblong-oblanceolate to linear-oblong, 5–22(25) × 1–2 mm;

tips retuse to obtuse;

surfaces abaxially strigillose, adaxially strigillose to glabrous;

stipules 1–7 mm; free.

Inflorescences

racemes dense but elongating and becoming looser, 10–35(50)-flowered;

peduncles (5)7–15 cm;

bracts 1.5–6 mm;

pedicels 0.8–2.5 mm;

bracteoles 0.

Flowers

erect to spreading at anthesis;

calyces gibbous-convex at bases, 8–10.5 mm, villous or villous-tomentulose with mostly white hairs;

tubes 7.5–9 mm;

teeth triangular, 1–2.1 mm;

corollas 15–18.6 mm, ochroleucous, unspotted;

ovules 12–19.

Fruits

unilocular; erect, oblong-ellipsoid; straight or slightly arcuate, laterally compressed, bicarinate, 12–15 × 3–4(5.4) mm, rugulose, sparsely pilosulose or glabrous;

valves coriaceous;

stipes 6–10 mm.

Astragalus tweedyi

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Dry hillsides, ridges, roadside banks, sagebrush. Flowering May–Jul. 100–1000 m. Col. WA. Native.

In Oregon, there are three species of Astragalus that have calyces that are obviously gibbous at the base so that the pedicel is attached obliquely: A. tweedyi, A. collinus, and A. curvicarpus; the three species are closely related. Astragalus tweedyi can be distinguished by its erect fruits, while the other species have pendulous fruits.

Source

Flora of Oregon, volume 2, page 675
Richard Halse

Sibling taxa