Astragalus sparsiflorus var. sparsiflorus

Pubescence sometimes more copius, always shorter than in var. majusculus, the hairs up to 0.2—0.5 mm. long; racemes (1) 2—6-flowered, the axis (0) 1.5-2.5 cm. long in fruit; banner recurved through 90°, 5.5-6.6 mm. long, 4.2-5 mm. wide; wings 5.2-5.9 mm. long, the claws 1—1.7 mm., the broadly oblanceolate or obovate, strongly but unequally incurved blades 4.2-4.5 mm. long, 1.7-2 mm. wide; keel 3.6—4 mm. long, the claws 1.4—1.8 mm., the nearly half-circular blades 2.3—2.6 mm. long, 1.4—1.8 mm. wide; pod obliquely half-obovate in profile, carinate ventrally by the concavely arched suture, openly sulcate dorsally in the lower ½-?, contracted distally into a broadly triangular, laterally flattened beak, the valves purplish-tinged or -mottled, the septum very narrow or obsolete, not over 0.2 mm. wide.—Collections: 7 (i); representative: Brandegee 562 (MO, NY); Penland 1693 (CAS, RM); Jones (from below Manitou) in 1878 (NY, POM); Ripley & Barneby 10,454 (CAS, NY, RSA); Ramaley 1378 (RM).

Habitats of var. majusculus, 5400—8000 feet, uncommon, upper canyon of the South Platte and thence south through the foothills of Pike’s Peak to the upper Arkansas River, in Denver, Park, Teller, El Paso, and Fremont Counties, Colorado.—Map No. 125.—Late May to August.

Astragalus sparsiflorus (with scattered flowers) Gray in Proc. Amer. Acad. 6: 205. 1864.—"On the lower Rocky Mountains of Colorado Territory, about lat. 40°, Hall & Harbour, no. 128."—Holotypus, GH! isotypi, BM, K, MO, NY, P, US!—Tragacantha sparsiflora (Gray) O. Kze., Rev. Gen. 948. 1891. Tium sparsiflorum (Gray) Rydb. in Bull. Torr. Club 32: 660. 1905. Batidophaca sparsiflora (Gray) Rydb. in N. Amer. Fl. 24 : 320. 1929.

The var. sparsiflorus is an extremely delicate little astragalus, remarkable for the small size of the leaflets, flowers, and fruits. Although the plants mature rapidly and ordinarily begin to bear flowers and pods within two or three months after germination of the seed, the root is potentially perennial; and even if never much thicker than a common pencil, it becomes decidedly woody in the second or third year. The pod of var. sparsiflorus, although so much shorter than that of var. majusculus, is formed after the same pattern. It is widest above the middle and then abruptly contracted into a quite similar beak which only appears more prominent because it remains unaltered while the fertile, bluntly triquetrous body is reduced in length by half.

In the Arkansas valley the Front Range milk-vetch enters the range of A. cerussatus, a species with flowers nearly as small and as few, but differing in its gray-villosulous herbage and much larger, bladdery-inflated pod.