. Development and activities of roots of crop plants; a study in crop ecology. Roots (Botany); Plant ecology; Crops and climate. . Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Weaver, John E. (John Ernest), 1884-1966; Jean, Frank Covert, 1880- joint author; Crist, John W. , joint author. Washington, Carnegie Institution of Washington - Stock Photo
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