Astragalus trichopodus var. lonchus (M.E.Jones) Barneby
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Authors
Rupert C. Barneby
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Authority
Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(2): 597-1188.
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Family
Fabaceae
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Scientific Name
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Type
"This is my No. 3083 from San Diego..."—Holotypus, collected by Jones on March 17, 1882, POM (2 sheets)! isotypi, CAS, NY!
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Synonyms
Astragalus leucopsis var. lonchus M.E.Jones, Phaca canescens Nutt. ex Torr. & A.Gray, Phaca leucopsis Torr. & A.Gray, Astragalus leucopsis (Torr. & A.Gray) Torr., Tragacantha leucopsis (Torr. & A.Gray) Kuntze, Phaca encenadae Rydb.
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Description
Variety Description - Loosely strigulose-villosulous with shorter, sinuous or curly together with some or many longer, ascending or spreading and incurved, more rarely all straight and subappressed hairs up to 0.4—0.75 mm. long, the stems commonly canescent, the foliage greenish-cinereous to almost white-felted, the leaflets equally pubescent on both sides or medially glabrescent, even quite glabrous above; stems mostly erect or ascending in clumps; racemes (12) 15-36-flowered, the axis (2) 3.5-11 cm. long in fruit; peduncles (5.5) 8—20 (30) cm. long; petals greenish-white or cream-colored, rarely veined with pale pink or purple, the keel rarely pink-tipped; banner 11.3-19 mm. long; keel 8.6-13.3 mm. long; stipe of the pod 5-15 mm. long, the body very obliquely ovoid, half-ovoid, half-ellipsoid, or lunately half-ellipsoid, (1.7) 2—4 (4.5) cm. long, (0.8) 1—1.8 (2.1) cm. in diameter, broadly cuneate or turbinate at base, contracted distally into a short, broadly deltoid, laterally flattened beak, shallowly sulcate ventrally, the valves finely strigulose with white or sometimes fuscous hairs, more rarely glabrous distally or throughout.
Distribution and Ecology - Coastal bluffs, mesas, and sandy fields near the ocean, sometimes hanging down from shaley clay cliffs or descending to shingle banks behind barrier beaches, mostly between 5 and 250 feet, but southward extending rarely up to 6 (10) miles inland and up to 1000 feet along seaward-running canyons, common and locally abundant in a narrow strip along the Pacific Ocean from Point Mugu, Ventura County, California, to the Santa Maria Plains in northern Baja California; Santa Cruz, Anacapa, and Catalina Islands, on the last also up to 1000 feet.—Map No. 112.—February to June and occasionally in fall and winter.
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Discussion
The ocean milk-vetch, var. lonchus, is listed first in order of precedence to emphasize the presumably primitive condition of the pod, through which the relationship of the whole species to A. asymmetricus is perceived. Within its range of dispersal the variety is the only astragalus (except for the nearly or perhaps actually sympatric var. trichopodus on Catalina) with pod at once greatly inflated and stipitate. Care, however, must be taken on the northern Channel Islands to distinguish the superficially similar A. curtipes, in which the shorter "stipe" is in reality a gynophore.
The variety is quite variable in size of the flower, in length of the calyx-teeth, and in density and distribution of the vesture, and the variations are correlated in some degree with distribution. Species such as this, confined to a narrow coastal strip, consist of a linear sequence of populations, and it is not surprising to find some characters becoming dominant at one end or the other, for the reticulate pattern of gene exchange feasible in organisms of continental dispersal is here hardly possible. In var. lonchus large flowers are prevalent northward, the smallest flowers occurring only in Lower California. Densely canescent foliage is common southward and only occasional northward. The pod is consistently strigulose north of San Diego and not infrequently glabrous below the boundary. The calyx-teeth southward are rarely more than 2 mm. long and commonly over 2 mm. northward. The correlation is incomplete, and no effective differentiation into discrete geographic races is apparent.
The vesture of var. lonchus is commonly composed of short, more or less crisped hairs mixed with longer, straighter, ascending ones, but either sort may predominate and occasionally one sort is absent or nearly so. The fluctuations are rather sporadic in distribution, even though plants of a given population are commonly alike in this respect. On the other hand, the leaflets sometimes vary in one small colony from glabrous to pubescent above.
A more important variant of var. lonchus occurs occasionally on Catalina and Santa Cruz Islands. Here plants are found apparently indistinguishable from the normal form except that the stipules, at least low on the stems or low on the more slender, lateral branches, are fully amplexicaul and connate-sheathing (cf. Fosberg S4778, S4618, POM, and C. B. Wolf 2751, RSA). Free-stipuled plants have been collected more commonly on both islands. It must be left to future field workers to discover whether the variants occur together or in separate populations.
As originally defined, var. lonchus was thought to differ from typical A. leucopsis in its elongate peduncles and flowers faintly suffused with purple coloring. There is no visible trace of anthocyanin in the type-series so far as known to me, and the plants appear to represent no more than robust minor variants easily matched in any large set of specimens. Rydberg’s P. encenadae is the state with glabrous fruit, although some isotypi have a few hairs on the proximal half of the pod-body. The species has been collected repeatedly near Ensenada, where glabrous- and puberulent-fruiting plants are found in about equal numbers.
The distribution of var. lonchus is so compact and natural that I have hesitated to incorporate in the range or map some strikingly discrepant data. In the first place the type-locality at Santa Barbara is almost certainly an error. The variety has not been seen since on the mainland north of Point Mugu, a point on the coast about forty miles southeast of Santa Barbara; it was unknown in the Santa Barbara region to C. F. Smith (Fl. Santa Barb. 43. 1952). Significantly the Nuttall labels associated with his Phaca canescens read at NY simply, "Upper California" and at PH "Angeles," and it seems likely that the "dry plains," hardly descriptive of the country around Santa Barbara, were in reality much farther south. Specimens labeled "Nanaimo, Vancouver Island" (J. Macoun 125, ND, NY) must surely have been a chance introduction, possibly in ballast from San Pedro or San Diego harbors. A specimen from "Piñería Alta, Sonora," collected by Schott (NY), may have originated at San Diego where the Boundary Survey naturalists botanized extensively; at least there is no modern record to substantiate an improbable range-extension.
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Objects
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Distribution
California United States of America North America| Baja California Mexico North America|