by University of Minnesota

1913

by University of Minnesota. Dept. of Botany

1926

by University of Minnesota

1890

by University of Minnesota

1926

by University of Minnesota

1925

by University of Minnesota

1913

by University of Minnesota. Agricultural Experiment Station

1925

by University of Minnesota (Minneapolis-St. Paul campus)

1923

by Columbia University

1916

by University of Minnesota

1911

by Denison University

1904

by University of Minnesota

1875