Astragalus hallii A.Gray
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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
"Valleys of the Rocky Mountains of Colorado Territory, lat. 39-41°, coll. Hall & Harbour, no. 121."—Holotypus, GH! isotypi, G, K, MO, NY, OXF, P, PH, US!
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Description
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Species Description - Relatively coarse and leafy, rarely quite slender, diffuse or weakly ascending, variably strigulose or villosulous with fine, ascending, incurved, or subappressed, sometimes partly sinuous hairs up to 0.25-0.8 (1) mm. long, the herbage green or cinereous, the leaflets commonly bicolored, yellowish- or brighter green and glabrous or medially glabrescent above; stems several or numerous, prostrate, decumbent, or assurgent, 1.5-5 dm. long, leafless and subterranean for a space of 1-18 cm., at emergence stouter and often divaricately branched at the first 1- few nodes, the main and lateral axes usually of about equal vigor, or the branches reduced to axillary spurs, rarely lacking; stipules (1.2) 2-7 mm. long, those at the lower nodes small, amplexicaul and connate into a scarious, glabrous, campanulate, truncate or bidentate sheath, the median and upper ones triangular-acuminate or lanceolate, subherbaceous, either strigulose or glabrescent dorsally, semiamplexicaul, or united by a low collar or stipular line; leaves 2-9 cm. long, the upper ones subsessile, with (11) 13-27 (31) oblong-oblanceolate, oblanceolate, or (especially in some lower leaves) obovate-cuneate to obcordate, obtuse, truncate, or retuse, flat or loosely folded leaflets (1.5) 3-13 mm. long; peduncles 3.5-11 cm. long, mostly as long or longer than the leaf; racemes at early anthesis rather densely, later more loosely (7) 10-28-flowered, the flowers loosely spreading, declined, or deflexed, then ± secund and retrorsely imbricated, the axis a little elongating, (1) 1.5-7 cm. long in fruit; bracts submembranous, lanceolate or narrowly ovate, 1.3-5 mm. long; pedicels at anthesis ascending, straight or somewhat arched outward, (1) 1.2-2.3 mm. long, in fruit either ascending, or strongly arched outward, or straight and abruptly divaricate, somewhat thickened, 2-4 mm. long; bracteoles 0-2, minute when present; calyx 5-9 mm. long, loosely strigulose or villosulous, the hairs white, fuscous, black, or mixed in varying proportions, the oblique disc 0.8-1.4 mm. deep, the submembranous, often purplish, deeply campanulate tube (4.4) 4.7-7 mm. long, (2.8) 3-4.3 (4.6) mm. in diameter, obliquely truncate at base or gibbous-saccate behind the pedicel, the deltoid or broadly triangular- subulate teeth 0.7-2.3 mm. long, the ventral pair commonly shortest; petals reddish-violet, pink-purple, or dull lilac to whitish tipped with lurid purple; banner ± sigmoidally arched, the claw incurved conformably with the base of the calyx-tube, the blade recurved through ± 40-45° (further in withering), broadly to narrowly rhombic-oblanceolate, -elliptic, or spatulate, deeply notched, (12.4) 13-18 (18.5) mm. long, (5.4) 6.4-9.6 (10) mm. wide; wings (11.5) 12-17 mm. long, the claws 5.1-7.5 mm., the narowly oblong, oblong-oblanceolate, or -obovate, obtuse, erose-emarginate, or (when broad) shallowly notched, nearly straight blades 7.2-11 mm. long, 2.1-3.4 mm. wide; keel 9-12 (12.3) mm. long, the claws (4.9) 5.2-1.2 mm., the half-obovate blades (4) 4.5-6.2 mm. long, (2.3) 2.5-3.3 mm. wide, abruptly incurved through 90-100° to the bluntly deltoid apex; anthers (0.5) 0.55-0.75 mm. long; pod spreading, ascending (when humistrate), declined, or deflexed, either stipitate or subsessile, the stout stipe varying from no longer than wide up to 4 (4.5) mm. long, the body variable in outline, barely tumescent to greatly inflated, 1.2-2.7 cm. long, (3) 4-12 mm. in diameter, the thinly fleshy, green or purplish, strigulose or more rarely villosulous valves becoming papery or thinly leathery; ovules 20—34; seeds brown or chestnut-brown, rarely purplish-black, ± pitted, dull, (1.9) 2.1-3.3 mm. long.
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Discussion
My concept of A. Hallii falls between that of Rydberg, who placed it apart from A. famelicus in a separate section of Pisophaca, and that of Jones, for whom the two species, together with A. puniceus and A. Greenei, formed parts of an inclusive and too loosely defined A. gracilentus. The history of A. gracilentus, which Jones misinterpreted, and of A. Greenei, both small-flowered plants more closely related to A. flexuosus, has been told under the heading of A. flexuosus var. Greenei; and A. puniceus is described below. It is agreed that A. Hallii and A. famelicus cannot be separated or defined in mutually exclusive terms and are best treated as no more than varietally distinct. The single differential character of Rydberg’s sect. Hallianae was an oblong or linear, uninflated pod, as opposed to the swollen, ellipsoid to obovoid fruit of its nearest kindred. The fruit of the typical phase of A. Hallii is ordinarily of narrowly oblong-elliptic or narrowly clavate outline and ± 5-6 mm. in diameter, but some otherwise identical plants from the Colorado Rockies have oblong-obovoid, considerably inflated pods up to 7.5-8.5 mm. in diameter (cf. Crandall & Cowen 4569 from South Park, whence there are also narrow-fruiting forms). From herbarium annotations it is clear that Rydberg evaded the difficulty posed by such specimens by referring them to an imaginary species fashioned out of several discordant elements and labeled with the confused name Pisophaca Greenei. Turning to the pod of A. famelicus, we find it ordinarily inflated and ± 7.5-12 mm. in diameter, but in southern Apache County, Arizona, and even on the Flagstaff Plateau, where the species is especially common, narrowly ellipsoid pods varying from 5.5 to 7 mm. in diameter are encountered occasionally. The flowers of A. Hallii and A. famelicus are closely similar in form and fluctuate metrically around nearly the same standard length. The pod of genuine A. Hallii is papery when ripe and varies from glabrous to strigulose; that of A. famelicus is consistently pubescent but varies from papery to leathery. In short the normal or commonest types of fruit are not alike, but individual plants occur within the range of each species which bear fruits almost identical in form and texture. The slight but apparently useful dissimilarity in the pubescence, mentioned in the key below, seems to offer the nearest to a constant differential character; in the context of sect. Scytocarpi it is an inconsiderable criterion. In general A. Hallii is more diffuse in growth-habit, greener and more amply leafy, and its weaker peduncles are humistrate, so that the pods tend to fall at random angles to the raceme- axis, whereas those of A. famelicus are nearly always declined from ascending, commonly stiffer peduncles. In varietal status A. famelicus must resume its old epithet fallax.