Astragalus altus

  • Title

    Astragalus altus

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Astragalus altus Wooton & Standl.

  • Description

    24. Astragalus altus

    Tall but slender, presumably perennial but the root unknown, the herbage strigulose with fine, straight, appressed or subappressed hairs up to 0.3-0.5 mm. long, the leaflets bicolored, pale green and pubescent beneath, deeper green and glabrous above; stems (reportedly several) erect or stiffly ascending, 5-6.5 dm. long, naked, glabrous, purplish at base, freely branching upward from well below the middle (at about 7-9 nodes preceding the first peduncle), the stiffly ascending branches all floriferous and sometimes again branched or spurred; stipules sub- membranous early becoming papery-scarious, 2.5-6 mm. long, dimorphic, the lowest largest, connate into a closely amplexicaul, bidentate, at length fragile and irregularly ruptured or circumscissile sheath, the median and upper ones progressively narrower, lanceolate or triangular-acuminate, very briefly connate at base or semiamplexicaul and free; leaves (2.5) 3.5-10 cm. long, the lowest shortly petioled, the rest subsessile, with (13) 15-25 ovate to lance- or oblong-elliptic, obtuse and mucronulate or subemarginate, flat leaflets (2) 3-12 mm. long; peduncles erect or incurved-ascending, 3.5-6 cm. long, a little longer or shorter than the leaf; racemes at first rather closely, at length loosely (15) 20-45-flowered, the flowers nodding, the axis a little elongating, 2.5-6.5 cm. long in fruit; bracts membranous, narrowly ovate to lance-acuminate, 1.2-2.5 mm. long; pedicels ascending, at length arched outward or in age straight and spreading, at anthesis 1-1.3 mm., in fruit scarcely thickened, 1.2-1.5 mm. long; bracteoles 0-2, minute when present; calyx 4.3-5.1 mm. long, thinly strigulose with black or mixed black and white hairs, the oblique disc 0.9-1.5 mm. deep, the pallid, campanulate tube 3.3-4 mm. long, 2.4-2.8 mm. in diameter, the triangular-subulate teeth 0.8-1.3 mm. long, the ventral pair commonly much shorter and often broader than the rest, the orifice oblique, the whole becoming papery, marcescent unruptured; petals apparently ochroleucous, described as "bright yellow"; banner gently recurved through 4550°, rhombic-elliptic or oblanceolate, shallowly notched, 9.6-10 mm. long, 3.4 4.8 mm. wide; wings 8.7-9.7 mm. long, the claws 3.5-4 mm., the narrowly elliptic or lance-elliptic, obtuse or erose, gently incurved blades 6-6.4 mm. long, 1.8-2.4 mm. wide; keel 6.4—7.6 mm. long, the claws 3—4 mm., the half-obovate blades 3.7-4.2 mm. long, 1.9-2.3 mm. wide, abruptly incurved through 90° to the bluntly deltoid apex; anthers 0.4—0.5 mm. long; pod pendulous, stipitate, the straight, slender, glabrous stipe 5—6 (or, ex char. "8—10") mm. long, the body obliquely half-oblance-ellipsoid, about 1.5 cm. long and 4.5 mm. in diameter, slightly incurved, cuneate at base, abruptly contracted at apex into a minute cusp, laterally compressed and bluntly trigonous, carinate ventrally by the prominent suture, shallowly and openly sulcate dorsally, the thinly papery valves sparsely strigulose with black or white and a few intermingled black hairs, inflexed as a hyaline septum 0.4 mm. wide; ovules 6—10; dehiscence and seeds unknown.—Collections: 3 (o); representative: Wooton (from Tularosa Creek) in 1901 (NMC); Wooton (topotypi) in July, 1899 (ARIZ, DS, RM).

    Openings in yellow pine forest, 6500—7800 feet, local and apparently rare, known only from the White and Sacramento Mountains, Otero County, New Mexico.—Map No. 9.—July to September.

    Astragalus altus (tall) Woot. & Standl, in Contrib. U. S. Nat. Herb. 16: 136. 1913.— "Type in the U.S. National Herbarium No. 690253, collected at Toboggan in the Sacramento Mountains, Otero County, July 31, 1899, by E. O. Wooton."—Holotypus, US! isotypus, NMC! —Atelophragma altum (Woot. & Standi.) Rydb. in Bull. Torr. Club 55: 161. 1928.

    The tall milk-vetch, A. altus, is related to the Mexican Strigulosi described up to this point, although not in particular to any one species. The flower is like that of A. strigulosus in its moderately curved banner and wings, but the pod differs in its marked lateral compression, vestigial septum, and few ovules. The pod is similar to that of A. Rusbyi, the species with which A. altus was originally compared; but the flowers of the latter are smaller and more loosely racemose, the petals more strongly incurved and little or irregularly graduated. As interpreted by Wooton & Standley, A. Rusbyi included a large element of A. Egglestonii, a species not then described, which differs further from A. altus in its short stipe, glabrous pod- walls, and broad septum.

    The tall, slender, and graceful stems of A. altus are freely branched in a paniculate fashion unusual in the genus. The flowers were described as bright yellow, but in the dry state are hardly yellower than many astragalus flowers which are ochroleucous when fresh. The color, as well as the nature of the root and caudex, needs investigation in the field. The species is apparently quite uncommon and has eluded my search on several occasions. Toboggan, the type-locality, was a small settlement in the Sacramento Mountains near Cloudcroft, now abandoned, although the name persists in the form of Toboggan Canyon, situated shortly to the south. According to Wooton and Standley (1910, p. 770) Toboggan stood at an elevation 400 meters lower than Cloudcroft.