Monographs Details: Astragalus brauntonii Parish
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(2): 597-1188.
Family:Fabaceae
Discussion:

354.  Astragalus Brauntonii

Tall, coarse perennial of rapid growth, with a thick taproot and ultimately indurated, trunklike base, densely villous-tomentulose throughout with fine, short, entangled and (especially the stems and leaf-rachises) longer, spreading, mostly wavy hairs up to (1.1) 1.3-1.7 mm. long, the stems white, the herbage canescent or greenish, the leaflets equally pubescent on both sides; stems several or numerous, erect and ascending (or becoming diffuse late in the year), stout, fistular, striate, 7-15 dm. long, commonly spurred at most nodes preceding the first peduncle or shortly branched upward, floriferous from about 5-12 distal axils; stipules submembranous becoming papery, 3-10 mm. long, deltoid- or lance-acuminate or -caudate, or the uppermost ones linear-lanceolate, pubescent dorsally, the blades deflexed, amplexicaul-decurrent around ?-½ the stems; leaves (3) 4-16 cm. long, the lowest shortly petioled, the rest subsessile, with 25-33 oblong-ovate or -obovate, or lance-elliptic, acute, obtuse and mucronulate, or apiculate, flat or loosely folded leaflets 3-20 mm. long, at least in age carinate dorsally by the midrib; peduncles spreading or incurved-ascending, 2.5-9 cm. long, much shorter than the leaf; racemes densely 35-60-flowered, narrowly cylindric or oblong, 15-20 mm. in diameter at full anthesis, sometimes interrupted at base, the flowers deflexed and retrorsely imbricated, the axis slightly elongating, 3.5-10 (14) cm. long in fruit; bracts membranous, narrowly lance-acuminate or -caudate, 2.5-5 mm. long, deflexed; pedicels ascending and arched outward, at anthesis 0.5-0.7 mm., in fruit thickened, (0.7) 1-1.5 mm. long; bracteoles 0; calyx 6.2-8.1 mm. long, villous- villosulous with white or partly with fuscous or black hairs, the strongly oblique, shallow disc 0.5-0.9 mm. deep, the ovoid-campanulate tube 3.3-4.1 mm. long, 3-3.8 mm. in diameter, distended dorsally at base but scarcely gibbous, the firmer, narrowly lance-acuminate or -caudate teeth 2.6-5 (6) mm. long, the whole becoming turgid, a little accrescent, papery-membranous, investing (ruptured or not) the base of the fruit; petals dull pinkish-purple, marcescent; banner oblanceolate or obovate-elliptic, shallowly emarginate or subentire, 9.1-11.7 mm. long, 4.5-5.5 mm. wide; wings 7.2-10 mm. long, the claws 3.3-4.6 mm., the obliquely elliptic or linear-oblanceolate, distally incurved blades 5.6-6.6 mm. long, 2-2.3 mm. wide; keel 6.4—8.5 mm. long, the claws 3.3-4.3 mm., the half-obovate blades 3-7—4.5 mm. long, 2.2-2.5 mm. wide, abruptly incurved through 95-100° to the rounded apex; anthers 0.5-0.6 mm. long; pod deflexed, deciduous from an incipient gynophore 0.5-0.7 mm. long, oblong or plumply lance-oblong in outline, nearly straight to gently incurved, 6.5-9 mm. long, (2.5) 3-4 mm. in diameter, obtuse or commonly retuse at base, abruptly contracted distally into an erect or slightly in- or decurved, subulate beak 1-1.5 mm. long, otherwise bluntly triquetrous, keeled ventrally by the prominent, thick suture, deeply grooved dorsally, the lateral angles broadly rounded, the green, thinly fleshy, villous or villous-tomentulose valves becoming stramineous, firmly papery, transversely reticulate beneath the vesture, inflexed through the proximal ½-? of the pod-body as a complete or subcomplete septum 1-1.3 mm. wide; seeds dark brown, pitted or wrinkled but somewhat lustrous, 1.4—2 mm. long.—Collections: 14 (ii); representative: Braunton 1281 (CAS, DS, K, MO, POM), in 1901 (DS), in 1907 (DS, TEX); Rixford (from Monrovia) in 1926 (CAS); Hastings (from Temescal Canyon) in 1942 (NY); C. B. Wolf 8000 (CAS, NY, POM).

Disturbed places and natural openings in chaparral, sometimes locally abundant on fire breaks, in stiff gravelly clay soils overlying granite or sandstone, 501500 feet, rare and local but in good years forming considerable colonies, known only from some seven stations (some now doubtless destroyed or threatened) in the foothills surrounding the plain of Los Angeles in Los Angeles and Orange Counties, southern California: south end of Santa Monica Mountains back from the immediate coastal bluffs; Sierra Madre near Monrovia; Sierra Peak, Santa Ana Mountains.—Map No. 158.—March to July.

Astragalus Brauntonii (Ernest Braunton, an early member of the California Botanical Society) Parish in Bull. S. Calif. Acad. Sci. 2: 26, Pl. 1. 1903.—"Above Santa Monica ... Dr. H. E. Hasse, June 25, 1899, in ripe fruit, and May, 1902 (type) in flower and immature fruit ..."—Holotypus, as designated by Parish, not found (1960) at DS; isotypi (3 sheets), US! paratypus Hasse in 1899, DS! (also POM, fragm!). A spm. collected near Sherman, June 18, 1901, Ernest Braunton, DS (herb. Parish.), POM, should probably be accounted another paratypus.—Brachyphragma Brauntonii (Parish) Rydb. in N. Amer. Fl. 24: 399. 1929.

The Braunton milk-vetch is a boldly handsome species, rivaling some of the coarser Old World Alopecuroidei in stature. Young plants are herbaceous down to the ground, but after a year or two develop a ligneous trunk several centimeters in diameter. The species is easily recognized by its tall, fistular stems whitened by a coat of spreading or entangled hairs, by the ample leaves composed of 12-16 pairs of dorsally keeled leaflets, and especially by the narrow, dense racemes of small, nodding, purplish flowers which arise from several distal axils and form a sort of panicle of spikes. As the flowers fade the petals turn brown and papery, investing with the somewhat accrescent calyx the base of the forming pod; they are not promptly shed as in most species of the genus. The Braunton milk-vetch is of easy culture in southern Californian gardens and should be preserved, if not for its beauty, at least for its rarity and biological interest. The long diameter of its known natural range is about eighty miles.