Astragalus curtipes A.Gray
-
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
-
Scientific Name
-
Type
"San Luis Obispo, California, on the side of a dry hill, April 13th. Dr. Brewer."—Holotypus, Brewer 460, GH! isotypi, CAS (dated "April 14"), US (dated "April, 1861")!
-
Synonyms
Tragacantha curtipes (A.Gray) Kuntze, Astragalus leucopsis var. curtipes (A.Gray) M.E.Jones, Phaca curtipes (A.Gray) Rydb., Astragalus leucopsis var. brachypus Greene, Astragalus leucopsis var. curtus E.Sheld.
-
Description
Species Description - Perennial, of moderate stature, with a thick taproot and stems at length somewhat indurated at base, strigulose and sometimes also minutely tomentulose with appressed or narrowly ascending, short and curly together with some longer, straight hairs up to 0.4-0.8 mm. long, the stems commonly densely so, cinereous or canescent but sometimes green, the herbage greenish-cinereous, the leaflets glabrous above; stems several, erect and ascending in clumps, 2.5-4 dm. long, shortly branched or spurred at most of the lower nodes, floriferous from 2-6 nodes above the middle, the inflorescences usually projected well above the leafy stems; stipules papery-membranous, pallid or stramineous, 2-12 mm. long, all amplexicaul and connate through more than half their length into an appressed, bidentate sheath, this sometimes ruptured by expansion of the stems, the uppermost ones sometimes free or nearly so to the base, all thinly pubescent dorsally; leaves (4) 5-16 cm. long, petioled or the uppermost only quite shortly so or subsessile, with 25-39 linear-oblong to narrowly obovate, obtuse or truncate- emarginate, flat or loosely folded leaflets (2) 5-25 mm. long; peduncles erect, slender but rather stiff, (5.5) 7-25 cm. long, usually surpassing (or on the islands shorter than) the leaf; racemes rather densely 15-35-flowered, the flowers early spreading and then declined, the axis a little elongating, 2-11 cm. long in fruit; bracts scarious, lanceolate or triangular-acuminate, 1.4-3.7 mm. long; pedicels at anthesis arched outward, 1-2.8 mm. long, in fruit somewhat thickened, straight, erect or narrowly ascending, 2.5-6 mm. long; bracteoles 0, or minute and scalelike; calyx 6-8.6 mm. long, rather densely strigulose with mixed black and white or all black hairs, the slightly to strongly oblique disc 0.8-1.5 mm. deep, the campanulate tube (3.7) 4-5 mm. long, (2.8) 3-4 mm. in diameter, the subulate or lanceolate teeth (1.5) 1.8-3.6 mm. long, the whole becoming papery, marcescent unruptured; petals creamy-white, concolorous, or the keel faintly lilac-tipped; banner gently recurved (at a point remote from the orifice of the calyx) through about 50°, rhombic-spatulate, shallowly emarginate or subentire, 13—16 mm. long, 6-8.8 mm. wide; wings as long or a little shorter, 12.4-15.3 mm. long, the claws 6—7.7 mm., the narrowly oblong-oblanceolate, obtuse or obscurely emarginate, often undulate-erose blades 7.4-9.4 mm. long, (2.1) 2.4-3.1 mm. wide, more or less incurved in the distal half; keel 10.7—12.7 mm. long, the claws 5.9-7.5 mm., the half obovate blades (4.8) 5-6.5 mm. long, 2.8—3.5 mm. wide, abruptly incurved through 85—95° to the bluntly deltoid, sometimes obscurely porrect apex; anthers 0.5-0.8 mm. long; pod ascending, loosely spreading, rarely declined, sessile on and disjointing from a stiff, stipelike gynophore 2.3-5.5 (6) mm. long, the body obliquely obovoid or half-obovoid-ellipsoid, bladdery-inflated, 2.3—3.6 cm. long, 1.2—1.8 (2) cm. in diameter, broadly to narrowly obconic at base, contracted distally into a short, broadly deltoid, laterally flattened, erect or slightly to strongly incurved beak, the sutures both filiform, the ventral one straight or slightly convexly or concavely arcuate, the dorsal one strongly gibbous-convex, the thin, pale green, sparsely strigulose valves becoming papery-membranous, stramineous, lustrous, subdiaphanous, delicately cross-reticulate, not inflexed, the funicular flange 0 or not over 0.3 mm. wide; dehiscence apical, after falling; ovules (26) 28-37; seeds brown, smooth but dull, 2.2-3.3 mm. long.
Distribution and Ecology - Grassy and brushy hillsides, rocky bluffs, and fallow fields near the coast, 50—450 feet, commonly associated with outcrops of serpentine or metamorphic bedrock, locally plentiful in scattered stations from the mouth of San Simeon Creek, San Luis Obispo County, south to near Point Arguello, Santa Barbara County, also (in slightly different form discussed below) on San Miguel and Santa Rosa Islands; a poorly known but probably distinct form isolated inland in San Benito County. Map No. 111.—(January) February to June, sometimes again in fall.
-
Discussion
The Morro milk-vetch, A. curtipes, is nearly related to A. Nuttallii with which it agrees in most technical respects other than the elevation of the pod on a gynophore which simulates the true stipe of sect. Trichopodi. It is a tall, graceful astragalus, of more slender growth than the rank, erect phases of A. Nuttallii var. virgatus found farther north and is much less copiously and softly villous than the prostrate var. Nuttallii native to coastal bluffs in the same; latitudes. Superficially it resembles some forms of A. trichopodus var. lonchus (= A. leucopsis). Jones at first subordinated the species to A. leucopsis as a variety and later concluded that it represented no more than "a freak of A. leucopsis with connate stipules." No one who has seen the colonies of A. curtipes, uniform in all critical characters, on the coastal hills of San Luis Obispo County, or who has learned to discriminate between a true stipe and a stipelike gynophore, will care to endorse this view. The Morro milk-vetch and A. trichopodus var. lonchus are apparently vicariant and allopatric; the latter extends north to the Channel Islands from its main area much farther south along the coast, where it is known only on Santa Cruz and Anacapa, while A. curtipes extends south only to Santa Rosa and San Miguel. The possible significance of the provocative similarity, combined with morphologically profound differences in the fruit of these two coastal milk-vetches, is discussed further in the introduction to sect. Densifolii.
The description of the Morro milk-vetch, prepared from samples of the populations found on the islands and the seaward slope of the outer Coast Ranges, takes no account of the evidently related but imperfectly known astragalus from San Benito County, probably a distinct entity. The mainland plant nearly always has stems much more densely pubescent than the leaves—the canescent vesture of the internodes contrasting with the scarious, thinly pubescent stipules and green or greenish-cinereous foliage—peduncles well surpassing the leaves, and whitish, concolorous petals. On the islands the common phase is more thinly pubescent throughout, with dorsally glabrous or glabrate stipules, green stems, peduncles about equaling the leaf, and a lilac keel-tip. The vesture of the insular plant lacks the shorter, curly type of hair nearly always present in continental A. curtipes. The collections cited above are of the strictly typical form; the following represent the island variant which seems scarcely to deserve taxonomic status: Munz & Crow 11,749, 11,828; Munz 11,745 (all POM); and the typus of A. leucopsis var. brachypus, which would furnish, if needed, a varietal epithet.
The form or relative of A. curtipes already mentioned as isolated in the interior is known to me from two fruiting collections from San Benito County (San Benito, J. T. Howell 11,075; Buena Vista Ranch, 4 miles southwest of Reinoso Peak, 1600 feet, Gregory S. Lyon 1862, both CAS) which differ collectively from A. curtipes in having enormous pods, 4.5-7 cm. long, 2.5-4 cm. in diameter. The leaflets vary from glabrous to pubescent above. The characters of this form have not been introduced into the description of A. curtipes, pending discovery of the flowers.
The typical, coastal form of the Morro milk-vetch was collected first in 1832 by the Irish botanist Thomas Coulter (Nos. 433, 434, K), but his material was passed over by Bentham as representing the then little-known A. asymmetricus.
-
Objects
-
Distribution
California United States of America North America|