William Francis Ganong Quote
The evidence seems to show beyond question that our present species of plants have descended by gradual evolution from simpler and fewer species which formerly existed, and which in turn were evolved from still simpler and fewer kinds - back, it is possible, to a single kind which throve in remotest antiquity.
A Textbook of Botany for Colleges, Chapter II (p. 10), The Macmillan Co. 1921
