Astragalus adsurgens var. robustior Hook.
-
Authors
Howard S. Irwin, 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
"Common in the mountain-vallies, from the Kettle Falls to the sources of the Columbia, on the west side of the Rocky Mountains. Douglas."—Holotypus, labeled "Mountain vallies and subalpine hills on the banks of Flathead River, Douglas." K! presumed isotyp
-
Synonyms
Astragalus nitidus Douglas ex Hook., Astragalus nitidus var. robustior (Hook.) M.E.Jones, Astragalus adsurgens subsp. robustior (Hook.) S.L.Welsh, Astragalus striatus Nutt. ex Torr. & A.Gray, Astragalus hypoglottis var. robustus Hook., Astragalus sulphurescens Rydb., Astragalus crandallii Gand., Astragalus adsurgens var. pauperculus Blank., , , , Astragalus sulphurescens var. pinicola E.H.Kelso
-
Description
Variety Description - Habit of the species; leaves 4—17 cm. long, with (9) 11—25 leaflets (4) 8-27 (33) mm. long; peduncles (3) 4—14 (16.5) cm. long; racemes (7) 16-50-flowered, the axis (0.6) 1.5—9 (13) cm. long in fruit; calyx 5.8—10.5 mm. long, strigulose with mixed black and white, all white, or rarely all black, straight or crisped hairs, the tube (4) 4.4-7 mm. long, (2) 2.3-3.2 mm. in diameter, the teeth subulate or subulate-setaceous, 1.4—4.2 mm. long, often crowded toward the dorsal side, the ventral sinus wide and deeply cut back, the orifice thus oblique; petals magenta-purple, reddish-lilac, dull blue, pale milky-white (the keel then maculate), or whitish drying creamy; banner 13-19.5 mm. long, 4-7 (8) mm. wide; wings 10.6-17.5 mm. long, the claws 5-8.3 mm., the blades 5.8-10 mm. long, 1.5-2.5 mm. wide; keel (8.8) 9.5-15 mm. long, the claws 4.9-8.3 mm., the blades 4.2-7 mm. long, 1.7-2.5 mm. wide; pod sessile or nearly so, the narrowly ovoid-, oblong-, or lance-ellipsoid body 7-12 mm. long, 2.3-3.8 mm. in diameter, densely pubescent with shorter sinuous and often some longer, straighter, mixed white and black or all white hairs; ovules 9-14 (16).
Distribution and Ecology - Plains, prairies, and dry hillsides, usually in bare rocky or gravelly places, northward on gravelly or shingly lake shores or river banks, in various soils but most abundant on sedimentary bedrock, widespread and locally abundant between 700 and 6400 feet along the east foothills of the Rocky Mountains and on the adjoining plains and prairies, from northeastern New Mexico to Alberta, and through the Peace River district into the northernmost Rocky Mountains in northeastern British Columbia, to Great Slave Lake in southwestern Mackenzie, and east (becoming less frequent) to northeastern and southwestern Manitoba, western Ontario, western (and one station in southeastern) Minnesota, and northern Iowa, in Colorado ascending westward into the higher valleys and parks up to 11,000 feet, where found on brushy hillsides, in mountain meadows, and in open pine forest; extending west of the Continental Divide to the Columbia Basin in southern British Columbia and northeastern Washington, to central Idaho, and to extreme northeastern and possibly central Utah; introduced in Yukon; reported from Kansas (Fernald, 1950, p. 911).—Map No. 77—May to August, fruiting into September northward and at great altitudes.
-
Discussion
A formidable synonymy has grown up around the common American form of the standing milk-vetch, var. robustior, and it remains as an index of the polymorphism encountered everywhere in A. adsurgens, whether in the Old or New Worlds. Apart from variation in stature and amplitude of the foliage, which can safely be attributed to accidents of environment or season, the variable features of var. robustior are size of the flowers, length of the calyx- teeth, color of the petals and of the hairs in the inflorescence (including the pod), and density or dispersal of the pubescence considered either separately or together. In his summary monograph Rydberg maintained three American species in the complex, stressing differential characters which for purposes of comparison and discussion may be tabulated as follows (abstracted from keys and descriptions in Rydberg, 1929, pp. 441, 449, 450).
A. striatus
Calyx tube.....4—6 mm.
Calyx teeth.....3—4 mm.
Petals.....purple rarely white
Leaflets.....13-25, strigose or glabrate above
Pod.....strigose
A. chandonnetii
Calyx tube.....4 mm.
Calyx teeth.....3—4 mm.
Petals.....white or ochroleucous
Leaflets.....13-19, silvery-silky
Pod.....white-hairy
A. sulphurescens
Calyx tube.....4-5 mm.
Calyx teeth.....as long as tube
Petals.....ochroleucous
Leaflets.....11-19, glabrate
Pod.....black-hairy
It will be seen than no significant difference was claimed for A. Chandonnetti other than the more silvery foliage. It represents, in fact, a series of pale- or white-flowered forms such as occur commonly in populations of bluish- or purple-flowered plants as well as in colonies of uniformly pallid hue. Color of the petals is not correlated with density of pubescence, and pale coloring of the flowers is not correlated with a white-hairy inflorescence or pod. The case of A. sulphurescens is different, for this apparently coincides with an incipient racial differentiation correlated with a range at comparatively high elevations in the Colorado Rocky Mountains. In the Front Range especially, but also farther southward, the leaflets of var. robustior are almost consistently glabrous above, a state unusual (though not unknown) elsewhere in the variety’s range. However the glabrescent and consequently green rather than ashen herbage of the Colorado populations does not go hand in hand with pallid petals. It must be emphasized further that the petals, even in the Front Range, are not truly ochroleucous, but white when fresh, fading yellowish (as the epithet sulphurescens literally means) in drying. In Colorado one finds concurrently with glabrescent foliage a tendency toward relatively long calyx-teeth, but similarly long teeth are found in silvery-pubescent plants sporadically northward. The presence of black (or fuscous) hairs on the pod, mixed with white in various proportions, is a common feature of the species, but it has no racial significance and no recognizable pattern of occurrence. The Colorado material that I have seen is quite heterogeneous in the technical characters singled out for emphasis by Rydberg, and is notable finally for commonly glabrate foliage, commonly long calyx-teeth (2.6-4.2 mm.), and commonly whitish petals, but all these characteristics are seldom associated in the same plant. The var. pinicola, of which the petals were described as "mostly white slightly yellow after drying," supposedly differed from A. sulphurescens in a slightly deeper calyx-tube and erect rather than "reflexed" (meaning, I suppose, distally recurved) teeth, but is only one of several minor variants in the Colorado mountains.
The remaining synonyms of var. robustior have little but a historic interest. The typus of A. Crandallii has not been examined, and no duplicate has been identified as such in an American herbarium. I follow Rydberg in interpreting it as a white-flowered form of var. robustior similar to that described as A. sulphurescens. Blankinship’s var. pauperculus corresponds with a slender or depauperate phase found occasionally in the Rocky Mountain foothills and very commonly on outcrops in the higher prairies. Relatively small flowers and short racemes are commonly but not consistently correlated with dwarf stature and narrow leaflets.
-
Objects
-
Distribution
New Mexico United States of America North America| Colorado United States of America North America| Wyoming United States of America North America| Utah United States of America North America| Nebraska United States of America North America| Iowa United States of America North America| Minnesota United States of America North America| South Dakota United States of America North America| North Dakota United States of America North America| Montana United States of America North America| Idaho United States of America North America| Washington United States of America North America| Manitoba Canada North America| Ontario Canada North America| Saskatchewan Canada North America| Alberta Canada North America| British Columbia Canada North America| Yukon Canada North America|