Astragalus collinus var. laurentii (Rydb.) 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
-
Scientific Name
-
Type
"Type collected east of Heppner [err. "Heffner"], Oregon, W. E. Lawrence 744" Holotypus, collected 17 July, 1917, NY! isotypi, RSA (with more exact data: a"at head of Hinton Creek, 13½ miles e. of Heppner, 3128-3375 ft." (comm. S. Conrade Head ex herb. Ore. State Coll.), US!
-
Synonyms
Homalobus laurentii Rydb., Astragalus laurentii (Rydb.) M.Peck
-
Description
Variety Description - Stipe of the pod (3.5) 5-10 mm. long; otherwise as given in the key. [Key: "Pod plumper and averaging shorter, obliquely ovate-oblong in profile, gently incurved, 0.8-1.5 cm. long, 3.3-4.2 mm. in diameter, typically villosulous with hairs up to 0.5-1 mm. long, exceptionally glabrous; ovules (7) 8-12"]
Distribution and Ecology - Dry grassy hills and hilltops, in sandy or stony clay soils derived from basalt, locally abundant and forming colonies, 2900-3600 feet, about the headwaters of Rock, Willow, and Butter Creeks in Morrow County, Thirty-mile Creek in extreme southeastern Gilliam County, and at about 2000 feet in the lower Umatilla Valley in northwestern Umatilla County, Oregon.—Map. No. 28.—May to July.
-
Discussion
The typus of the Lawrence milk-vetch and the collections cited as representative originated at points a few miles apart along the road from Heppner to Lena, and probably consist of random examples from one large population. There is only one other record, from the Umatilla Valley near Echo, of exactly typical var. Laurentii (Schallig SI90, RSA). In the strict sense the variety differs from var. collinus only in the relatively short and broad, gently incurved, few-ovulate pod beset with longer spreading hairs, but the modification is a striking one. North of Heppner, along upper Rock Creek (where first collected by Leiberg, No. 66, NY) in the southwest corner of Morrow County, and extending west to Thirty-mile Creek in adjoining Gilliam County, A. collinus is represented by a form with pods similar to that of var. Laurentii but averaging a little longer and entirely glabrous. I have suggested (1956, p. 487) that these plants may have come into being as a result of introgression between var. Laurentii and the closely related A. curvicarpus var. subglaber, which reaches its eastern limit along the lower John Day River in Gilliam County. However, the copious vesture of the herbage and the impressed reticulation of the pod-valves are characteristic of A. collinus, and the plants occur in extensive and uniform populations which are certainly self-perpetuating. For the present the glabrous-fruiting form is interpreted as a minor variant of var. Laurentii.
-
Objects
-
Distribution
Oregon United States of America North America|