Astragalus columbianus Barneby

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

Astragalus columbianus Barneby

Type

Washington: Walla Walla region, Washington Territory, June, 1883, Brandegee 720 and Tweedy 610 (apparently one collection twice numbered).—Holotypus, NY (herb. Canby.)! isotypi (Brandegee 720), GH, UC, US!

Description

Species Description - Caulescent perennials, with woody taproot and thick, multicipital, knotty root-crown, strigulose with straight, appressed hairs up to 0.4-0.7 mm. long, the stems and herbage cinereous or the foliage greenish, the leaflets pubescent or sub- glabrate above; stems apparently diffuse, (0.8) 1.5-3.5 dm. long, leafless at base, simple or branching upward from near the base, floriferous from 1-3 nodes below the middle; stipules 1-6 mm. long, the lowest membranous, ovate, obtuse, more than semiamplexicaul, the upper ones narrower or shorter, deltoid, triangular, or lanceolate, herbaceous with membranous margins; leaves 3.5-5.5 cm. long, petioled, with 5-13 oblong-elliptic, narrowly oblanceolate, or linear-oblong, obtuse, or obtuse and mucronulate, flat or loosely folded leaflets 3-12 mm. long; peduncles ascending, rather stout, 1.2-2.5 cm. long; racemes subcapitately but loosely 2-10- flowered, the flowers ascending, the axis not or scarcely elongating, less than 1 cm. long in fruit; bracts thinly herbaceous becoming papery, lance- or deltoid-acuminate, 1-5 mm. long; pedicels ascending, at early anthesis 0.6-1 mm., in fruit greatly thickened and ± 1.5 mm. long; bracteoles 0—2, setaceous when present, calyx ± 11-11.6 mm. long, strigulose with appressed black hairs, the subsymmetric disc 1.2-1.4 mm. deep, the deeply campanulate, submembranous tube 6.6-7 mm. long, 3.8-4 mm. in diameter, the narrowly lance-subulate teeth 4-4.8 mm long; petals apparently whitish; banner recurved through ± 35°, oblanceolate, 18.1-19.5 mm. long, 7.5-7.8 mm. wide; wings 18.5-19.5 mm. long, the claws 7.3-7.6 mm., the narrowly oblong, obtuse, straight blades 12.3-13 mm. long, 2.8 mm. wide; keel 13.1—13.6 mm. long, the claws it 7.5 mm., the half-obovate blades ± 6.7 mm. long, 3.5 mm. wide, incurved through ± 85° to the bluntly deltoid apex; anthers 0.7-0.8 mm. long; pod apparently ascending and probably humistrate, sessile, narrowly oblong- or lance-ellipsoid, incurved through ¼ to over Vi a circle, 2.5-4 cm. long, 8.5-10.5 mm. in diameter, obtuse or subtruncate at base, acuminate distally into an elongate, laterally flattened beak, otherwise dorsiventrally compressed, carinate ventrally by the suture, flattened or depressed dorsally, the lateral angles rounded but rugulose-reticulate when ripe, the green, fleshy, glabrous valves becoming subligneous, prominently cross-reticulate, not inflexed; dehiscence apical, through the beak, after falling; ovules 48-51; seeds brown or olivaceous, pitted and wrinkled, sublustrous, 2.5-3 mm. long.

Distribution and Ecology - Rocky slopes at low elevations in the sagebrush zone, on basalt, known positively only from along the Columbia River above Priest’s Rapids, Yakima County, Washington.—Not mapped—April to June.

Latin Diagnosis - inter Argophyllos genuinos caulibus elongatis, foliolis paucis 2-6-jugis, pedunculis abbreviatis, floribus albidis notabilis. Legumen fere A. argophylli nisi glabrum, sed habitus in sectione peculiaris, forsan subsectionem propriam sistens.—Perennis, diffusa, appresse strigulosa; stipulis liberis; foliis 3.5—5.5 cm. longis petiolatis, foliolis paucis angustis 3—12 mm. longis; pedunculis abbreviatis validis 1.5—2.5 cm. longis; racemis brevissime 2—10-floris; calycis strigulosi tubo profunde campanulato fere 7 mm. longo, dentibus lanceolatis 4—5 mm. longis; petalis albidis, iis A. argophylli et affinium similibus, vexillo circa 18—19.5 mm. longo; legumine sessili, deciduo, oblongo-ellipsoideo, infra rostrum incurvum de latere compressum obcompresso, valvulis carnosis glabris demum sublignosis ruguloso-reticulatis, haud inflexis; ovulis circa 50.

Discussion

The Columbia milk-vetch was one of several interesting and rare plants collected in the Columbia Basin by T. S. Brandegee and Frank Tweedy while they were working under W. M. Canby for the Northern Transcontinental Survey, a biological investigation underwritten by the Northern Pacific Railway. The specimens of this astragalus have been passed over by students of the genus as representing A. Casei, a species known otherwise from farther south in western Nevada and adjoining California and easily distinguished by its much longer peduncles and open racemes of more numerous and pubescent pods. I have associated with the typus, which is in advanced fruit, a flowering collection from Priest’s Rapids on the Columbia (cited above) which agrees in all important details comparable at such different periods of growth. A composite picture is thus built up of a singular astragalus which has all the technical attributes of the Argophylli, but a facies and habit of growth so peculiar that no immediate relationship within the section is apparent. The species is introduced at this place until more can be learned about it and its probable affinities. Except that it is hairless, the pod is quite like that of some forms of A. argophyllus or A. tephrodes var. brachylobus, and its mode of dehiscence after falling is characteristic of the present section. The more remarkable features of the species are its exceptionally well-developed stems, which apparently continue to elongate beyond the last peduncle after the flowers have faded; the very short peduncles and subcapitately few-flowered racemes; and the white or whitish flowers. At anthesis the plant could be confused in the Columbia Basin only with A. vallaris, which is endemic to the Grand Canyon of the Snake River, and there is no sympatric species at all similar to it when in fruit. Modern collections, which should be sought along the banks of the Columbia upstream from the mouth of the Snake, are greatly desired.

Distribution

Washington United States of America North America|