There is a rich history that resides in biological collections, such as herbaria – and discoveries, as well – as Don Pfister, the Asa Gray Professor of Systematic Botany and Curator of the Farlow Library and Herbarium, discusses here:
On the evening of Thursday the 25th of May, beginning at 7:30PM, the Philadelphia Botanical Club will have its monthly meeting, and Ned Barnard and Catriona Briger, co-authors of Philadelphia Trees: A Field Guide to the City and the Surrounding Delaware Valley, will talk about their book, in a lecture titled “Trees of Philadelphia”.
For more information, see here: http://darwin.ansp.org/hosted/botany_club/meeting.html
The history of plants is also underground, and not just in the roots:
A very much older tree was also found underground not far from there, a number of decades ago:
To read more about that, see here (Chapter 1): http://fitlersquarepress.com/chapters/