Monographs Details: Astragalus praelongus var. lonchopus Barneby
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
Description:Variety Description - Calyx-teeth 3-6.5 mm. long, subulate or subulate-attenuate; pod erect or more rarely spreading, wholly similar to that of var. Ellisiae except for the long stipe (4.5—8 mm. long), the body 2—3 cm. long, 7—9 mm. in diameter, rounded or shallowly sulcate dorsally, the valves commonly minutely puberulent.

Distribution and Ecology - Habitats of var. praelongus, apparently confined to sandstone, 3700-5400 feet, locally plentiful in the canyons of the San Juan and Colorado Rivers in extreme northern Apache and Navajo Counties, Arizona, San Juan County, Utah, and southwestern (probably Montezuma County), Colorado, to be expected in northeastern San Juan County, New Mexico.—Map No. 73.—Late April to July, the pods often persisting over winter on withered stems.

Discussion:The var. lonchopus is distinguished consistently from other forms of its species by the long stipe alone, but the plants are often remarkable for their long calyx-teeth and a tendency toward narrow and subacute leaflets matched only rarely in var. praelongus. Its known range extends from the Four Corners country westward for about one hundred miles and north to the Natural Bridges in White Canyon; in this area it is apparently the only stinking milk-vetch, occurring in the same habitats as var. praelongus and var. Ellisiae, but sympatric with neither. The substance of the variety has been known for many years, for it is probably (at least in great part) the Rydbergiella arcta sensu Rydberg (1917, p. 501) and the Astragalus arctus sensu Tidestrom (1925, p. 327), as well as the Jonesiella arcta cited in synonymy above. These three names go back through the illegitimate A. Preussii var. arctus Sheld. to A. Preussii var. latus Jones, a minor variant of genuine A. Preussii. The pods of var. Preussii and A. praelongus are similar in orientation, shape, and stipe, but that of the Preuss milk-vetch is of papery texture, truly unilocular, and devoid of pulpy filaments in the cavity. The two species grow close together in southeastern Utah but are easily distinguished both by the fruits and by the entirely different flowers (cf. key to the subsections of sect. Preussiani).
Distribution:Arizona United States of America North America| Utah United States of America North America| Colorado United States of America North America|