This section is from the book "The Gardener's Monthly And Horticulturist V20", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
In the current number of your journal for April, 1878, page 113, J. M. says: "It would be interesting to know the farthest northern point that the Willow Oak, Quercus phellos has been found growing wild." In the spring of 1862, Mr. Hensel, Sr., brought me a branchlet, with leaves on it, of a beautiful large tree, growing in an open field, as he informed me, desiring a name for it, stating where it grew. I considered it the Willow Oak. June 13th, 1864, stopping, with others, on our way to the Susquehanna, at the public house in Martinville, Lancaster Co., Pa., it occurred to me that we were near the locality of said oak. On inquiry, one of the party had seen the tree before, and Professor Porter, then of Franklin College, had given him the name. We walked out a short distance, and sure enough, there stood a vigorous tree, densely covered with its pretty foliage, forming a full round head, about thirty feet high, a veritable Quercus phellos. How it came there the oldest inhabitant could not inform us.
This brings it somewhat farther north than Philadelphia.