Experimental studies on the nature of species.
Clausen, Jens(Jens Christian),1891-1969,author.
Keck, David D.(David Daniels),1903-author.
Hiesey, William M.(William McKinley),1903-author.
Carnegie Institution of Washington.
Includes bibliographical references (pages 124-125) and index.
Plant ecology.
Heredity.
Botany