One of the recent consulting projects for the Morris Arboretum Urban Forestry consulting Group involved assisting Jerry Shrack, the Director of Horticulture at the Philadelphia Zoo, in the preservation of one of Philadelphia’s oldest residents. Tucked into a forgotten corner of the Zoo behind a maintenance building is a massive English elm (Ulmus procera) that is said to have been planted by John Penn, the son of William Penn, in 1784 when he built his home “Solitude” which stands today just a few yards away from this venerable giant. At almost seven feet across at shoulder height and 100 feet tall the Penn English elm at 230 years old is the oldest and largest tree in their collection and is a great source of pride to Jerry.

When Jerry assumed his current position he found this specimen hidden behind a screen of sucker sprouts with a crown that was full of deadwood and storm damaged limbs after years of neglect. Having taken several of the courses offered through the School of Arboriculture at the Arboretum Jerry recognized the importance of this treasure and called on the Urban Foresters from Morris for assistance. A program of care was outlined and Ken LeRoy from John B. Ward and sons was retained to prune and cable as well as fertilize and monitor for insect and disease problems. Now several years on the fruits of his labor are evident. The vigor of the tree has improved and some of the structural issues have been addressed. The basal sucker sprouts have been removed and the knobby trunk with multiple galls and protrusions is visible for all to see and admire.

With an eye to the future, Jerry utilized some of those suckers and rooted the cuttings in his greenhouse to bring a new generation of Penn English elms. In November a sapling was planted at Marquand Park in Princeton N.J. A few yards away is a cutting from the Treaty Elm that stands in front of College Hall on the University of Pennsylvania campus. As these trees develop they will be referred to as the Father and Son trees in the Penn grove. We have Jerry and Ken both to thank for their efforts in preserving this horticultural treasure and helping us to honor a piece of the history around us. 


Written by Robert Wells, Associate Director of Arboriculture Outreach, Morris Arboretum