Bartram, John

Mohl, Hugo von (1805-1872), a German botanist, helped develop the cell theory. According to this theory, all plants and animals are made up of… See more » Gray, Asa (1810-1888), was the leading authority of his time on plant life in the United States. Gray specialized in the classification and… See more » Candolle, Augustin Pyrame de (1778-1841), a Swiss botanist, published many books about plant classification and its theoretical aspects. His… See more »