Astragalus egglestonii (Rydb.) Kearney & Peebles
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Authors
Rupert C. Barneby
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Authority
Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(1): 1-596.
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Family
Fabaceae
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Scientific Name
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Type
"Type collected in Datil Forest, Socorro County, New Mexico, September 7, 1920, Eggleston 17216..." Holotypus, with additional data: H"Hillside north of Morley shearing sheds, Datil, 2270 m.," NY!; isotypi, CAS, NY, US!
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Synonyms
Tium egglestonii Rydb.
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Description
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Species Description - Rather slender but often tall and stiff perennial, with a taproot and shortly forking caudex at or just below soil-level, appearing nearly glabrous, but bearing a few, scattered, straight, appressed hairs up to 0.25-0.45 mm. long on the upper parts, the margins and midribs of the leaflets, the inflorescence thinly black-strigulose; stems several, erect and strictly ascending, (1.5) 2-5.5 dm. long, simple or commonly spurred or shortly branched at 1—3 (6) nodes preceding the first peduncle, floriferous from near or above the middle, leafless at base; stipules 1.5—5 mm. long, somewhat dimorphic, the small, scarious-papery lower ones connate into a short, bidentate sheath or amplexicaul as a narrow band or collar around the stem (sometimes reduced to a stipular line), the upper ones progressively longer and narrower, deltoid-acuminate or broadly lanceolate, thinly herbaceous, about semiamplexicaul; leaves (3) 4—12 cm. long, shortly petioled or the uppermost sessile or subsessile, with (17) 21—29 oblong-oblanceolate or elliptic, obtuse, obtuse and mucronulate, or subacute, flat or loosely folded leaflets 3—13 mm. long, the midrib prominent below; racemes loosely, sometimes remotely (5) 10—30- flowered, the flowers early nodding, the axis elongating, (1.5) 3—19 cm. long in fruit; bracts submembranous, ovate or lanceolate, 1-2 mm. long; pedicels early spreading or recurved, at anthesis (0.7) 1—1.8 mm. long, in fruit either strongly recurved, or straight and then either divaricate or deflexed, thickened, 2—3.5 mm. long, persistent; bracteoles 2, minute, scarious; calyx 3.4—4.3 mm. long, strigulose with black or black and a few white hairs, the oblique disc 0.5-1 mm. deep, the campanulate tube 2.1-2.7 mm. long, 1.6-2.2 mm. in diameter, the subulate teeth 1-2 mm. long, the whole becoming papery, marcescent unruptured; petals whitish or dull greenish-ochroleucous, immaculate; banner abruptly recurved through 90° (or further in withering), rhombic-ovate or ovate-cuneate, shallowly notched or entire, 5.8-8 mm. long, 4.2-6.4 mm. wide; wings (0.2 mm. longer to 0.7 mm. shorter than the banner) 5.8-7.3 mm. long, the claws 1.8-2.4 mm., the lunately oblong, obtuse or obscurely emarginate blades 4.4-5.6 mm. long, 1.6-2.3 mm. wide, strongly but unequally incurved, the left one further than the right; keel 4.2-5.6 mm. long, the claws 1.9-2.5 mm., the nearly half-circular blades 2.7-3.5 mm. long, 1.6-2.2 mm. wide, abruptly incurved through ± 130° to the bluntly deltoid apex; anthers 0.35-0.5 mm. long; pod pendulous, stipitate, the stipe 1.5 2.5 mm. long, the body linear-oblong or -oblanceolate in outline, straight or very slightly in- or decurved, 1.5-3 cm. long, (2.5) 3-4 mm. in diameter, tapering at base into the stipe, cuneate at apex, triquetrously compressed, bluntly carinate ventrally by the suture, the lateral angles rounded, the lateral faces low-convex, the dorsal face openly sulcate, the thin, green, glabrous valves becoming papery, sub- diaphanous, stramineous, lustrous, finely cross-reticulate, inflexed as a complete septum 1.4-1.9 mm. wide; dehiscence apical and also from the base upward through the ventral suture; ovules 12-16; seeds dark purplish- or chestnut-brown, sometimes purple-dotted, nearly smooth or irregularly pitted, somewhat lustrous, 2-2.9 mm. long.
Distribution and Ecology - Meadows and open pine woods, sometimes along or near streams, in either dry or temporarily moist soils, on basaltic and sometimes granitic bedrock, 65008800 feet, rather common locally on and about the Continental Divide in west- central New Mexico, particularly in the Mogollon, San Francisco, Datil, Zuni, and San Mateo Mountains, extending west to the headwaters of the Little Colorado in the White Mountains, Apache County, Arizona.—Map No. 9.—July to September.
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Discussion
The Eggleston milk-vetch was collected in Socorro County, New Mexico, at least as early as 1897, by C. L. Herrick; this and subsequent gatherings by Prof. Wooton were misidentified as A. Rusbyi, a related species narrowly endemic to central Arizona which differs, inter alia, in its longer stipitate, strigulose pod. Within its area of dispersal in the mountains forming the watershed between the Rio Grande and the Gila and Little Colorado Rivers, A. Egglestonii is the only astragalus flowering in late summer with erect stems and very small, loosely racemose, nodding flowers, succeeded by linear-oblong, shortly stipitate, trigonous fruits. The petals are commonly whitish with no hint of pigmentation, though they vary in very dry places to a pale greenish-yellow.
A remarkable plant, provisionally referred to A. Egglestonii although differing in several important particulars, has been collected in yellow pine forest, at 6200 feet elevation along Turkey Creek, 6 miles west of Point of Pines and about 70 miles east of San Carlos in northeast Graham County, Arizona (V. Bohrer 430, ARIZ, CAS). It differs from the Eggleston milk-vetch in its diffuse, flexuous stems, white-strigulose calyx, leaflets only 13-17 in number, and remotely few- (10-13) flowered racemes. The petals were apparently pinkish when fresh, the dry banner being purple-striate. The pod is like that of A. Egglestonii, with stipe 1.5 mm. long and body 2.1 cm. long, 3.5 mm. in diameter, subtrigonous, grooved dorsally and 16- ovulate; but the valves are strigulose. More material is required to establish the status of this form, the aberrant characters of which have been omitted for the present from the specific description.
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Objects
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Distribution
Arizona United States of America North America| New Mexico United States of America North America|