Mutations, variations, and relationships of the Oenotheras :
MacDougal, Daniel Trembly,1865-1958.
Vail, Anna Murray,1863-joint author.
Shull, George Harrison,1874-1954,joint author.
Washington, D.C. : Carnegie Institution of Washington,
1907.
Bibliography: p. 91-92.
Oenothera.
Plants