It wasn’t long after Timothy Block and Ann Fowler Rhoads had published a comprehensive guide to Pennsylvania’s plants—“The Plants of Pennsylvania” (Penn Press, 2000)—that the duo realized their work was only half done.

Four years and more than a few long nights later, the pair has finally finished work on the follow-up book they knew they had to write—“Trees of Pennsylvania” (Penn Press, 2004), a comprehensive guide to Pennsylvania’s more than 200 known tree species.

It sounds like too many trees to take in in just one day.

But with a single hike around the 92-acre University of Pennsylvania Morris Arboretum in Chestnut Hill, where both Block and Rhoads work, you can see just about all of them.

The Arboretum boasts one of the finest collection of trees anywhere, and because it is the official arboretum of the Commonwealth of Pennsylvania, just a handful of the trees covered in Block and Rhoads’ book can’t be found there.

“ I can think of, maybe, only a half-dozen trees in the book that we don’t have samples of here,” says Block, director of botany at the arboretum.

Written for all

Other state tree guides have been published in the past—including “Trees of Pennsylvania, the Atlantic States and the Lake States,” written by former Morris Arboretum director Hui Lin Li—but Block and Rhoads (senior scientist of the Pennsylvania Flora Project at the Arboretum) say the time for a new guide had come.

They believe no other guide offers the breadth of information readers will find in “Trees of Pennsylvania.”
“ This is a book that you’ll be able to pick up and read, just because it’s really, really interesting,” says Block.

The authors went out of their way to make the book readable for the general public, so that even the botanically challenged can learn a thing or two about the state’s natural world by reading it.

Along with detailed information on each tree—flowering and fruiting time, autumn leaf color and the size of the largest recorded specimen—the book also features line drawings by botanical artist Anna Anisko, photographs, range maps and keys to help readers identify specific species.

“ We went to great lengths to simplify things,” Block says. “ We really went out of our way to make things simple for people.”

A stroll in the park

With Block and Rhoads’ guide in hand, readers should be able to connect what they see in the book with what they’ll find at the Arboretum.

In fact, that’s the reason the book was written, Rhoads says.

“ It just seemed that there was a need for a book that could help people better understand and appreciate this aspect of our natural surroundings,” Rhoads says.

“ Trees shape and give structure to the landscape in such a prominent way.”

Among the most impressive trees to be found at the Arboretum is Penn’s prized white oak, a fine specimen of one of the Eastern United States’ most prominent species.

The view from below the tree’s branches, Arboretum staffers say, is among the best on the grounds. That white oak, in fact, will grace the cover of “Trees of Pennsylvania” when it is published next month.

That doesn’t mean it’s the authors’ favorite, though—both insist choosing just one is impossible.

“ I have trouble picking a single favorite,” Rhoads says. “There are just so many interesting trees and beautiful trees that I’d have to beg off from singling one out.”

The Arboretum is open year-round, except for Thanksgiving, Christmas Eve and Christmas Day, New Year’s Eve and New Year’s Day. For more information, call 215-247-5777.