Monographs Details: Astragalus kentrophyta var. coloradoensis M.E.Jones
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(1): 1-596.
Synonyms:Astragalus montanus var. coloradoensis (M.E.Jones) M.E.Jones
Description:Variety Description - Either diffuse and loosely matted, or assurgent, the stems up to 12 cm. long, the longest internodes up to 1-1.5 (2) cm. long, the foliage early becoming rigid and prickly, loosely strigulose with sinuous and some straighter, ascending, or largely subappressed hairs up to 0.6-0.9 mm. long, the stems canescent, the leaflets cinereous on both sides; stipules 1.5-7.5 mm. long, amplexicaul but connate at base only, with narrowly lanceolate or caudate, at length acerose free blades; leaves 9-24 mm. long, with 3-7, mostly 5, linear-elliptic leaflets acuminate at both ends, 4—15 mm. long, the vulnerant spinule 1.5-2.5 mm. long; peduncles 2-6 mm. long, the axis of the (1) 2-flowered raceme produced up to 8 mm. beyond the second flower; calyx 6-8.3 mm. long, the tube 2.4-3.3 mm. long, 2-2.3 mm. in diameter, the linear-setiform teeth 3.4-5 mm. long; petals pale purple; banner ovate- or elliptic-cuneate, 7.3-10 mm. long, 4—6 mm. wide; wings 6.6-9.6 mm. long, the claws 2.1-2.3 mm., the blades 4.9-6.7 mm. long, 1.5-2.9 mm. wide; keel 4.8-6.2 mm. long, the claws 2.3-2.8 mm., the blades 3-3.6 mm. long, 1.7-1.9 mm. wide; pod subsymmetrically ellipsoid, lance- or oblong-ellipsoid, (5) 7-10 mm. long, 2.8-4 mm. in diameter, straight or nearly so, shortly acuminate but scarcely beaked; ovules 4—8.

Distribution and Ecology - Canyon benches, sandy bluffs, and talus under cliffs, on sandstone, 3200— 5000 feet, local, known only from the canyons of the Colorado River and tributary streams in southeastern Utah (near Hanksville and Burr Desert, Wayne County; Glen Canyon and vicinity, eastern Kane and adjoining San Juan Counties) and extreme northern Arizona (Lee’s Ferry, Coconino County). Map No. 38. April to June.

Discussion:The canyon kentrophyta, var. coloradoensis, was passed over in the preliminary revision (Barnebv 1951 p 102) as a large-fruiting variant of var. elatus, admittedly a remarkable form but one too little know at the time to permit evaluation of its status. Recently collected plants from Utah have the long, broad pod of the typus combined with a flower calyx substantially longer than anything known hitherto in A. Kentrophyta, much larger than those of var. elatus, the form of the species with which var. coloradoensis has othervise most in common. The canyon kentrophyta is of shorter duration than var elatus and has a more slender root and caudex. It blooms a month or more earlier and occupies an ecological niche at slightly lower elevations. Not only are the flowers and pods much larger. but the ovules are, at least on the average, more numerous by one or two pairs. The stipules even low on the stems are less stroglv connate than in var. elatus or in most other forms of A. Kenthrophyta, but not truly free as Jones described them, unless the sheath is ruptured by expansion of the stem.
Distribution:Utah United States of America North America| Arizona United States of America North America|