OregonFlora: Astragalus iodanthus

	Astragalus iodanthus
	Humboldt River milkvetch
Habit	Plants perennial, caulescent, strigillose to villosulous, hairs basifixed.
Stems	several, prostrate to decumbent, 3–40 cm.
Leaves	2–8 cm; leaflets 7–21, obovate to oblong or oblanceolate to elliptic, 3–18 × 2–12 mm; tips truncate to retuse, obtuse or mucronate; surfaces sparsely strigose to glabrous; stipules 2–6 mm; free.
Inflorescences	racemes 7–21-flowered; peduncles 1–4.5 cm; bracts 1–3 mm; pedicels 0.3–2 mm; bracteoles 0–2.
Flowers	widely ascending or spreading at anthesis; calyces 3.3–8 mm, strigillose or rarely villosulous with black or mixture of black and white hairs; tubes 2.6–5 mm; teeth subulate or triangular, 1–3 mm; corollas 9–15.5 mm, bright purple to lilac or whitish, sometimes lilac-tinged or -tipped; ovules 14–30.
Fruits	unilocular to semibilocular, deflexed, humistrately spreading, lanceolate, linear-lanceolate or lance-elliptic, curved through a quarter- to half-circle or more, dorsiventrally or trigonously compressed, ventrally sulcate, 15–40 × 2.5–8.5 mm, often mottled, strigillose or glabrous; valves stiffly papery or subcoriaceous; stipes 0.

	Astragalus iodanthus
Distribution	[WildflowerSearch map] [BONAP county map]
Discussion	2 varieties.
Source	Flora of Oregon, volume 2, page 666 Richard Halse
Sibling taxa	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. 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. iodanthus var. diaphanoides, A. iodanthus var. iodanthus
Web links	Local floras: CA, OR Local Web sites: CalFlora, CalPhotos, 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 iodanthus

Humboldt River milkvetch

Habit

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

Stems

several, prostrate to decumbent, 3–40 cm.

Leaves

2–8 cm;

leaflets 7–21, obovate to oblong or oblanceolate to elliptic, 3–18 × 2–12 mm;

tips truncate to retuse, obtuse or mucronate;

surfaces sparsely strigose to glabrous;

stipules 2–6 mm; free.

Inflorescences

racemes 7–21-flowered;

peduncles 1–4.5 cm;

bracts 1–3 mm;

pedicels 0.3–2 mm;

bracteoles 0–2.

Flowers

widely ascending or spreading at anthesis;

calyces 3.3–8 mm, strigillose or rarely villosulous with black or mixture of black and white hairs;

tubes 2.6–5 mm;

teeth subulate or triangular, 1–3 mm;

corollas 9–15.5 mm, bright purple to lilac or whitish, sometimes lilac-tinged or -tipped;

ovules 14–30.

Fruits

unilocular to semibilocular, deflexed, humistrately spreading, lanceolate, linear-lanceolate or lance-elliptic, curved through a quarter- to half-circle or more, dorsiventrally or trigonously compressed, ventrally sulcate, 15–40 × 2.5–8.5 mm, often mottled, strigillose or glabrous;

valves stiffly papery or subcoriaceous;

stipes 0.