Astragalus Traskiae

  • Title

    Astragalus Traskiae

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Astragalus traskiae Eastw.

  • Description

    133. Astragalus Traskiae

    Diffuse, leafy, perennial, with a woody taproot and superficial root-crown or caudex (sometimes buried in drifting sand), densely villous-tomentulose throughout with extremely fine, contorted and entangled, together with some few straighter, widely ascending hairs up to 0.7—1 mm. long, the stems white-pannose, the herbage canescent, the leaflets equally pubescent on both sides, the inflorescence largely or wholly fuscous-pubescent; stems several, decumbent and ascending, (0.8) 1.5—2 (4) dm. long, branched at base and bearing short, leafy spurs at nearly all nodes preceding the first peduncle, together forming low, mounded clumps;  stipules deltoid or triangular-acuminate, 1.5-4 mm. long, semiamplexicaul, densely pubescent dorsally; leaves (4) 5-10 cm. long, all petioled, with 21-29 ovate, obovate, oval, or oblong-elliptic, obtuse or emarginate, flat, dorsally keeled leaflets (2.5) 5-15 mm. long, diminishing upward along the rachis; peduncles 4-14 cm. long, at anthesis ascending, weighed down by the fruit and then drooping or humistrate, either longer or shorter than the leaf; racemes loosely (or at first densely) 12-30- flowered, the axis more or less elongating, 2.5-8 cm. long in fruit; bracts submembranous, lance-subulate, 1.5-2 mm. long; pedicels at anthesis ascending, rather stout, in fruit either ascending or spreading, 1-1.5 mm. long; bracteoles commonly 2, sometimes minute or hairlike; calyx 7.5-9 mm. long, the slightly oblique disc 1.3-1.5 mm. deep, the deeply campanulate tube 5.2-6.2 mm. long, 3.5-4 mm. in diameter, the broadly subulate teeth 2.3-3.5 mm. long, the whole becoming papery, marcescent unruptured; petals ochroleucous, concolorous, drying yellowish; banner oblanceolate or rhombic-elliptic, shallowly notched, 14.2-17.5 mm. long, 6-8.2 mm. wide; wings 12.2-14.5 mm. long, the claws 6.5-7.1 mm., the oblong or oblong-oblanceolate, straight or nearly straight, obtuse, truncate, or obliquely emarginate blades 7.2-8.9 mm. long, 2.1-2.6 mm. wide; keel 10.2-12.9 mm. long, the claws 6.7-7.4 mm., the half-obovate blades 5.2-6.1 mm. long, 2.6-2.9 mm. wide, incurved through about 85° to the bluntly deltoid apex; anthers 0.5-0.6 mm. long; pod essentially pendulous and vertical, spreading or even ascending from horizontal or humistrate peduncles, the straight, slender stipe 4-8.5 mm. long, the body obliquely lance-oblong, half-oval, or half-elliptic in profile, very slightly incurved, 8—16 mm. long, 3.2-5.5 mm. in diameter, broadly cuneate or subtruncate at base, contracted distally into a stout, rigid, subulate beak 1.5-4.5 mm. long, triquetrously compressed with obtuse angles, carinate ventrally by the thickened, straight or slightly incurved suture, openly grooved dorsally, the thinly fleshy, villous-tomentulose valves becoming greenish-stramineous, leathery, transversely reticulate, inflexed as a complete or almost complete septum 1.1-1.8 mm. wide; ovules 12-16; seeds (not seen ripe) ± 2 mm. long.—Collections: 4 (o); representative: Trask (from Santa Barbara Island) in 1901 (ND); Moran 826 (CAS, DS); Dr. Laye Miller (from San Nicolas Island) in 1938 (SBM).

    Sandy windswept ocean bluffs, gullied banks, and coastal dunes, up to 650 feet, known only from San Nicolas and Santa Barbara Islands off the coast of southern California.—Map No. 109.—March to July, probably intermittently through the year.

    Astragalus Traskiae (Luella Blanche Engle Trask, 1865-1916, pioneer explorer of California’s insular flora) Eastw. in Proc. Calif. Acad. Sci. Ill, 1: 102, Pl. VIII, fig. 6. 1898.—"San Nicolas Island ... collected in April, 1897, by Mrs. Blanche Trask . .. "—Holotypus, CAS! isotypi, MO, POM!—A. Nevinii var. Traskiae (Eastw.) Jones, Contrib. West. Bot. 10: 87. 1902 ("Traskae"). Tium Traskiae (Eastw.) Rydb. in N. Amer. Fl. 24: 390. 1929.

    The Trask milk-vetch has been reported from Anacapa (Abrams, 1944, p. 591) and San Clemente Islands (Eastwood in Leafl. West. Bot. 3: 66), but is known to me through concrete specimens only from San Nicolas and Santa Barbara, where it is the only perennial astragalus. The San Clemente record was probably based on material of the closely related and endemic A. Nevinii, a species very similar in its tomentose vesture and habit of growth but differing in its smaller flowers, fewer leaflets, and glabrous pod. The Anacapa record has not been traced to the source but very likely originated, like that of A. Nevinii from the same island, through misidentified flowering material of A. miguelensis. The latter, common on Anacapa, superficially resembles the Neviniani in its white-woolly foliage and yellowish flowers, but may be distinguished even at anthesis by the connate stipules and later by the sessile, inflated, essentially unilocular pod.

    The Trask and Nevin milk-vetches are copy-book examples of insular endemism and of divergent evolution presumably of an orthogenetic type; their close interrelationship is self- evident and has never been disputed. At one point Jones reduced A. Traskiae to varietal rank, but he subsequently restored it (1923, p. 264) to that of species, to which its differential characters fully entitle it. Jepson has interpreted the two species as forming one variable entity and described (1936, p. 369) the pod as "puberulent to tomentulose, glabrate"; but this apparent simplification only serves to conceal the more complex and more interesting facts.