Astragalus nuttallianus var. austrinus |
Astragalus sect. Leptocarpi |
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rio fronteras milkvetch, smallflower milkvetch, southern small flower milk vetch |
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Habit | Plants strigulose or hirsutulous. | Herbs annual, biennial, or perennial, caulescent; caudex superficial. |
Stems | (1–)3–25(–35) cm. |
single or few to many. |
Leaves | 1–6.5 cm; leaflets 7–11(–17), blades often narrowly elliptic, sometimes broader proximally, apex rounded. |
odd-pinnate, petiolate to subsessile; leaflets (3 or)5–25(or 27). |
Racemes | (1–)2–5(–8)-flowered; axis very short in fruit. |
subumbellate or loosely flowered, flowers ascending, spreading, or declined. |
Peduncles | 3–10 cm. |
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Flowers | calyx 3.7–5.4 mm, silvery-pilose, tube (1.5–)2–3 mm, lobes 1.8–2.1 mm; corolla white or tipped pink or purple, banner (4–)5.5–7 mm; keel apex triangular-acute or sharply deltate, usually beaklike. |
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Corollas | usually pink-purple, purple or purple-tinged or -tipped, ochroleucous, or lilac, rarely whitish, banner recurved through 20–80°, keel apex acute, round, deltate, or triangular-acuminate, sometimes slightly beaklike. |
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Calyx | tubes campanulate. |
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Legumes | 13–24 × 1.8–2.8(–3) mm, glabrous or strigulose. |
deciduous, usually sessile, rarely short-stipitate, short gynophore sometimes present, ascending, spreading to declined, incurved-ascending, or pendulous, mostly linear to linear-oblanceoloid, oblong, or crescentic, sometimes 3-sided, rarely ellipsoid or fleshy, straight or incurved, rarely slightly decurved, compressed laterally, slightly 3-sided or subterete, bilocular. |
Seeds | 14–18. |
(2–)4–30. |
Hairs | basifixed or malpighian. |
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Stipules | distinct. |
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2n | = 24. |
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Astragalus nuttallianus var. austrinus |
Astragalus sect. Leptocarpi |
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Phenology | Flowering Mar–May (summer–fall). | |
Habitat | On limestone substrates, in various vegetative types. | |
Elevation | 600–2200 m. (2000–7200 ft.) | |
Distribution |
AZ; CA; CO; KS; NM; OK; TX; Mexico (Baja California, Chihuahua, Coahuila, Durango, Nuevo León, Puebla, Sonora) |
w United States; se United States; n Mexico |
Discussion | Variety austrinus occurs from southern Kansas to the southern tip of Texas and northern Mexico, and westward to Arizona and southern California, where it grades into var. imperfectus (D. Isely 1998). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Species 24 (18 in the flora). Section Leptocarpi is complex morphologically, with eight subsections recognized, one of them, subsect. Coahuilani Barneby, occurring only in northern Mexico. The subsections within the flora area are: subsect. Pringleani Barneby (Astragalus nothoxys); subsect. Arizonici Barneby (A. arizonicus); subsect. Mohavenses Barneby (A. albens, A. mohavensis); subsect. Parvi Barneby (A. hypoxylus); subsect. Tricarinati (Rydberg) Barneby (A. bernardinus, A. tricarinatus); subsect. Californici (A. Gray) Barneby (A. acutirostris, A. breweri, A. claranus, A. emoryanus, A. pauperculus, A. rattanii, A. tener); and subsect. Leptocarpi (M. E. Jones) Barneby (A. leptocarpus, A. lindheimeri, A. nuttallianus, A. nyensis). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 11. | FNA vol. 11. |
Parent taxa | ||
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Hamosa austrina, A. austrinus | |
Name authority | (Small) Barneby in F. Shreve and I. L. Wiggins: Veg. Fl. Sonoran Desert, 709. (1964) | M. E. Jones: Rev. N.-Amer. Astragalus, 266. (1923) |
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