Astragalus Kentrophyta var. Kentrophyta

  • Title

    Astragalus Kentrophyta var. Kentrophyta

  • Author(s)

    Rupert C. Barneby

  • Scientific Name

    Astragalus kentrophyta A.Gray var. kentrophyta

  • Description

    94c. Astragalus Kentrophyta var. Kentrophyta

    Decumbent, loosely matted, the longest intemodes up to 4-15 mm. long, the plants sometimes flowering as seedlings and the stem then solitary, erect, only 2-5 mm. long, but ultimately freely branching and at length forming mats up to 3 dm. in diameter, the stems and leaves loosely strigulose with ascending, straight or sinuous hairs up to 0.5-0.9 mm. long, mostly attached laterally at base, but nearly always some minutely spurred at base and thus dolabriform, the stems commonly canescent, the leaflets greenish or greenish-cinereous, glabrous or medially gla- brescent above, in age stiff and prickly; stipules 1.5-6 mm. long, dimorphic, the lowest connate into a short sheath, the upper ones longer, acerose in age; leaves (7) 10-25 mm. long, with 5-7, relatively distant, linear-oblanceolate leaflets up to 7-12 mm. long, the terminal spinule 0.5-1.2 mm. long; peduncles subobsolete, or up to 2 mm. long, mostly concealed by stipules; calyx 3.4—4 mm. long, the tube 1.9-2.4 mm. long, 1.4-1.8 mm. in diameter, the teeth 1.4-2 mm. long; petals whitish; banner 4—5.5 mm. long, 2-3 mm. wide; wings 3.8-5.2 mm. long, the claws 1.5-2 mm., the blades 2.9-3.7 mm. long, 1.1-1.4 mm. wide; keel 3-4 mm. long, the claws 1.2—1.9 mm., the blades 2—2.4 mm. long, 1—1.3 mm. wide; pod subsymmetrically ovoid-lenticular, (3.5) 4—7 mm. long, (2) 2.4—3.8 mm. in diameter, minutely cuspidate but not beaked; ovules 2—3 (4). Collections. 13 (o); representative: A. Nelson 3621 (NY, RM); J. Macoun 10,191 (ND), C. L. Porter 4308 (RM, SMU, TEX); Rydberg 79 (NY).

    Bluffs, dunes, and gullied ridges in the badlands, mostly below 5000 feet, scattered and apparently not common, known from scattered stations on the northwestern Great Plains from southwestern Wyoming and western Nebraska north to southwestern Saskatchewan and southern Alberta; reported from western Kansas. —Map No. 37.—June to September.

    Astragalus Kentrophyta (spiny growth, the old generic name) Gray in Proc. Philad. Acad. 1863, p. 60. 1863, and in Proc. Amer. Acad. 6: 231. 1864 based on Kentrophyta montana Nutt. el T. & G., Fl. N. Amer. 6: 231. 1838.—"Hills of the Platte, in naked Holotypus, labeled "Kentrophyta montana. Platte Hills, BM! isotypus, labeled Kentorus * montanus. R. Mts.," NY!—Tragacantha montana (Nutt.) O. Kze., Rev. Gen. 941. . Astragalus montanus (Nutt.) Jones, Rev. Astrag. 80, Pl. 5. 1923 (non L.,_175J).

    Kentrophyta viridis (green) Nutt. ex T. & G„ Fl. N Amer. 1: 353. 1838.- With the preceding [K. montana]."—Holotypus, labeled "Kentorus * viridis. R. Mts. Platte.," BM! isotypus, NY!—Astragalus Kentrophyta ß viridis (Nutt.) Hook, in Lond. Jour. Bot. 6: 215. 1847. A. viridis (Nutt.) Sheld. in Minn. Bot. Stud. 1: 118. 1895 (non Bge., 1869). Phaca viridis (Nutt.) Piper in Contrib. U. S. Nat. Herb. 11 (Fl. Wash.): 374. 1906. A. tegetarius var. viridis (Nutt.) Barneby in Leafl. West. Bot. 6: 97. 1951.

    Through an accident of history Nuttall’s kentrophyta was the first form of its species to be described. However, it is probably only a marginal derivative of the biotypically richer and biologically more successful var. implexus, which has pioneered onto the higher prairies and there acquired by mutation, balanced against a new lowland environment, some individuality of aspect and a few minor differential characters. It is listed and keyed above among the forms with dolabriform hair-attachment; but laterally affixed hairs are few and hard to find in some individuals, and the basal spur is always short, sometimes obscure in nearly all the hairs. In its whitish petals, narrow banner, and few ovules the var. Kentrophyta more nearly resembles var. Jessiae, which differs in its smaller fruit and leaflets equally pubescent on both sides. The contrast between linear-oblanceolate and linear-elliptic leaflets emphasized in my revision (Barneby, 1951, p. 98) has not been confirmed in material examined subsequently.

    Nuttall’s kentrophyta is unquestionably perennial or potentially so, but it seems to be short-lived, rarely persisting long enough to acquire a suffruticulose caudex and often flowering precociously. Seedling plants with almost filiform taproot and solitary, erect stem a few con- timeters long are capable of flowering and setting fruit even before the cotyledons have withered.

    The record of A. Kentrophyta from Kansas ("Wichita County," acc. B. B. Smyth in Trans. Kans. Acad. 15: 61. 1897) has not been confirmed and is omitted from the map.