Astragalus lentiginosus var. palans (M.E.Jones) M.E.Jones
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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(2): 597-1188.
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Family
Fabaceae
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Scientific Name
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Type
"Montezuma Canon, Utah, June 1, 1892, coll. by Miss Alice Eastwood."—Holotypus, POM! isotypi, CAS, GH, MO (dated "May 29"), NY (fragm.), UC!
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Synonyms
Astragalus palans M.E.Jones, Tium palans (M.E.Jones) Rydb., Astragalus amplexus Payson, Hamosa amplexa (Payson) Rydb., Tium amplexum (Payson) Rydb.
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Description
Variety Description - Perennial, sometimes of short duration, thinly strigulose with appressed or subappressed hairs up to 0.45—0.7 mm. long, the herbage green or yellowish-green, the leaflets glabrous above or on both sides, exceptionally pubcscent on both sides; stems several, erect or incurved-ascending, commonly stout and purplish, (1) 1.5-3.5 (4) dm. long; leaves (3.5) 5-11 cm. long, with 13-21 (23) broadly obovate-cuneate, oblong-elliptic, more rarely oblong-oblanceolate or (especially in some lower leaves) suborbicular-obcordate, obtuse, emarginate, or subacute, flat or loosely folded leaflets (3) 5—17 (26) mm. long; peduncles erect or incurved, much shorter than or equaling the leaf; racemes (6) 10-28-flowered, the axis either scarcely or greatly elongating, (1) 2—12 (14.5) cm. long in fruit; calyx 6.3—9.4 mm. long, either white- or black-strigulose, the cylindric or deeply campanulate tube 4.7-6.8 mm. long, 2.4-3.6 mm. in diameter, the teeth (0.9) 1.1-3 (4) mm. long; petals purple; banner broadly obovate-spatulate, rhombic-obovate, or -oblanceolate, 13.5-17.5 (18.3) mm. long, 6.8-10 mm. wide; wings 11.8-16.8 mm., the claws 5.4-7.3 (8) mm., the blades 6.9-10.2 (12) mm. long; keel 10.115 (15.3) mm. long, the claws 5.4—7.5 mm., the blades 5.8—9 mm. long, 2.5—3.6 (3.8) mm wide; pod spreading, declined, and thence incurved-ascending, or ascending at a wide angle, obliquely linear-lanceolate to narrowly ovate-acuminate in profile, nearly straight to lunately or hamately incurved, (1.2) 1.5—2.7 cm. long, 4-7.5 mm. in diameter, subterete to somewhat laterally compressed when little curved, dorsiventrally so when greatly curved, contracted distally into a triangular-acuminate, long-cuspidate, unilocular beak about 5—8 mm. long, the some what fleshy, green or brightly mottled, glabrous or less often strigulose valves becoming leathery or stiffly papery, stramineous or finally blackish, inflexed as a complete or subcomplete septum 1.4-2.5 mm. wide; ovules 20-42.
Distribution and Ecology - Open mesas, sandy rock-ledges and canyon-terraces, rocky washes, and alkaline sandy flats, mostly 4000-7000 feet, on sandstone, sometimes on limestone, perhaps occasionally on granitic or volcanic bedrock, usually in piñon-juniper forest, locally plentiful in scattered stations in the Colorado Basin south of Tavaputs Escarpment in southwestern Colorado, southeastern Utah, and northern Coconino and Navajo Counties, Arizona, westward to the Grand Canyon; also at lower elevations (± 2500 feet and possibly down to 1000 feet) in the Virgin Valley, Washington County, Utah, and along the Colorado River below Grand Canyon in northern Mohave County, Arizona.—Map No. 131.—April to June.
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Discussion
To those who have become familiar with the freckled milk-vetch through its commoner manifestations on the deserts of California or in the Great Basin, the inclusion of var. palans in the A. lentiginosus complex comes at first as a disagreeable or even unacceptable surprise. However its close relationship is quickly comprehended as its various phases are encountered, and is reflected in the mere existence of such a combination as A. palans var. aranosus, proposed by the botanist most intimately concerned with the discovery and description of these and allied forms. The great variation in the pod of var. palans has been emphasized and illustrated elsewhere (Barneby, 1945, p. 135, Pl. IV, figs. 23-26) but is so important to an understanding of the variety’s circumscription that it can be mentioned again without apology. The fruit varies from slenderly fusiform and straight or almost so to incurved through about a halfcircle. A comparatively short, little-incurved, clawlike pod, which ascends from the raceme, closely resembles the least-swollen states of var. araneosus or var. diphysus. Curvature commonly becomes more pronounced with increasing length and leads to the extreme (nomenclaturally typical) phase in which the pod is technically declined from an arched pedicel but so strongly bent inward that the tip is brought into a more or less vertical attitude. In addition to the variation in outline, the valves may be brightly mottled with red or purple, green and concolorous, or green suffused with red, and may be either glabrous or (as in the typus of A. amplexus) strigulose. The mode of compression also varies greatly, and the transverse section may be round, round and emarginate at either one or both sutures, or decidedly obcordate. Like many species which consist of populations isolated one from the other by barriers to migration as effective as the deeply sculptured canyons of the Colorado Plateau, var. palans consists of numerous races differing further in density and distribution of the pubescence, size of flowers, and length of fruiting raceme. Until the patterns of variation and geographic dispersal have been compared in greater detail than is possible at present, it cannot be foretold whether the polymorphic concept adopted in these pages may yield or not to further elaboration. In this connection the populations in northwestern Arizona, remarkable for their straight erect or ascending pod and leaves pubescent on both sides, will deserve special scrutiny (cf. Lemmon 3116, 3326, wrongly referred in my revision to var. mokiacensis). It is also conceivable that A. Bryantii, referred for technical reasons to another section of the genus, may prove to be an anomalous offshoot of the same group of forms.
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Objects
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Distribution
Arizona United States of America North America|