Astragalus coltonii M.E.Jones var. coltonii
-
Authors
Rupert C. Barneby
-
Authority
Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(1): 1-596.
-
Family
Fabaceae
-
Scientific Name
-
Synonyms
Homalobus coltoni Rydb.
-
Description
Variety Description - Sparsely leafy, ephedroid or ± junceous, the numerous stems arising from the buried root-crown or (especially on rocky slopes) from an aerial, ultimately forking and suffruticulose caudex; leaflets, when present, either pubescent on both sides or glabrous above, greenish or cinereous; leaves 2-10 cm. long, the lowest ones petioled and bearing 1—5 distant pairs of linear, rarely linear-oblong, obtuse or subacute, flat or commonly involute leaflets 4—10 (14) mm. long, the terminal one confluent, the upper leaves, sometimes nearly all, reduced to a wiry or subfiliform rachis often expanded at tip into a linear phyllode representing the terminal leaflet; peduncles 1—3 dm. long; racemes (2) 5—20 flowered; stipe of the pod 4—9 mm. long, the body 2.5-3.2 cm. long, (3) 3.5-5.2 mm. in diameter.
Distribution and Ecology - Dry banks, gullied clay knolls, cobblestone bluffs, sometimes on sandy rock ledges or on boulder-strewn talus under cliffs, mostly 5500-6600, rarely up to 8000 feet, mostly on sandstone, locally plentiful along the west edge of the Colorado Basin from the upper Price River in Carbon County south to the Kaiparowits Plateau in Kane County, Utah; Sevier Valley in Sevier County.—Map No. 25.— April to June.
-
Discussion
In dry springs and always with the advance of summer the Colton milk-vetch forms inconspicuous broomlike tufts of almost leafless stems not easily recognized as an astragalus. However in late April or May of favorable years, the plants erupt into a mass of pink-purple which rivals that of Hedysarum boreale Nutt, in richness of color and is quickly followed by strings of bladelike pods pendulous on thready stipes. In its area of dispersal it is the only ephedroid astragalus with bright purple flowers. Mention has already been made of the variation in position of the root-crown. An exposed caudex, anomalous in sect. Lonchocarpi, is correlated with talus habitat and is believed to be the result of physical accident rather than an inherent character. The var. aphyllus represents an extreme stage in leaf-reduction.
Jones has recorded (1923, p. 71) the Colton milk-vetch from Tintic Valley in eastern Juab County, Utah, but there is no corresponding specimen at POM, and the record may have been based on an old misidentification of A. pinonis. A more recent range-extension to the Uinta Basin (Graham, 1937, p. 246) is based on collections of A. (Pectinati) saurinus, a species similar in its junceous growth-habit and purple flowers, but very different in its truly connate stipules and sessile pod. The var. Coltoni was apparently first collected somewhere in Utah by Capt. Bishop in 1872, but the specimens were fragmentary and mixed with the typus of A. Episcopus (NY).
-
Objects
-
Distribution
Utah United States of America North America|