If you walk along the Wissahickon, you’ll see plenty of hemlocks (Tsuga canadensis) – these are evergreens, with flattened needle-like leaves that have a whitish striping on their undersides and cones that are about an inch high, and so are reasonably easy to differentiate from the other common conifer you’ll see up around there, the white pine.
Hemlocks along the Wissahickon can be a pretty good size, with trunks over a foot across and tops reaching dozens of feet towards the sky. But there used to be much larger hemlocks here.
In 1933, a book was published called “Penn’s Woods: 1682 – 1932″. It was written by Edward Embree Wildman, with the goal of documenting all the trees in the area that were alive at the time of William Penn’s arrival in 1682 and were still living at time of the 250th anniversary of that arrival – in 1932, that is.
And Wildman noted some very large hemlocks, growing along the Wissahickon -
“Before leaving the city we have four more Penn trees to record. One of these is the largest hemlock we have on record. These trees grow in our beautiful Wissahickon Valley, along the lower bridle path. A beech nine feet, four inches in girth stands on the Jenkins Estate, Far Country. A half mile below is the great hemlock, twelve feet, five inches in girth. It is about 100 yard south of the Walnut Lane Bridge near the stream. Two other hemlocks nearby measure more than nine feet at breast height.”
Wildman (1933), p. 57
I had never seen 4′ wide (note that Wildman measured the circumference, not the diameter) hemlocks in the Wissahickon before, but you never know, and so on the morning of the 4th of May (2013) I went up to the Walnut Lane bridge, paced off 100 yards on the western side of the creek, and didn’t see any hemlocks there; but the far side of the creek was so lushly green that I couldn’t really see into it that well, and so I wanted to go back and do the same thing on the eastern side – and I did that the following evening.
And, as I was walking there, with evening falling and along the interceptor sewer that’s right nearby the upper trail on the west side of the creek, as I got close to the Walnut Lane Bridge, I looked up at it (the bridge, that is), and it seemed about a hundred yards away, and I looked down to my left and saw a little grove in the crepuscular haze, and I wondered if that was where these enormous trees had been…
Well, in the interest of accuracy and/or precision, I went up to the bridge and paced off a hundred yards back downstream (from whence I came, that is), and I saw that I’d gotten it right and that the little grove down by the stream was about a hundred yards south of the bridge, and so that was quite likely where Wildman had seen that enormous hemlock … but I didn’t see any hemlocks down there, and most of the trees that I saw there looked to be less than 80 years old, based on their size, except for one large tulip poplar, which looked to be about a meter across, and so is probably ~100 years old, and therefore would’ve been there, as a youngster, when that tall hemlock was there, and it would’ve possibly grown right alongside it, occasionally in its shadow even, perhaps (though not much, of course, given that tulip poplars like light).
In 1996, there was a paper published in Bartonia, the Journal of the Philadelphia Botanical Club, written By Dr. John M. Fogg, Jr., that documented the flora of the Wissahickon Valley. It had the appropriate title, “Annotated checklist of the plants of the Wissahickon Valley” and in it he does, of course, mention hemlocks, calling them “One of the commonest and most handsomest trees of the valley.” And he goes on to say: “Often forming pure stands, especially on the west or north facing slopes, as at: Walnut Lane, Valley Green, south of Rex Avenue, above Covered Bridge.” (Fogg, 1996; Bartonia vol. 59)
Dr. Fogg did not mention the enormous hemlocks from Wildman’s book, however, he (Fogg, that is), didn’t mention much in the way of specific individual plants for other entries in this checklist, and so this doesn’t mean he didn’t see these ancient, enormous trees – and, he was botanizing the Wissahickon in the 1930s, and so I’m quite certain he would have seen them, in addition to the numerous other ones he would have frequently encountered in his visits to the Wissahickon.
Hemlocks have been common in the Wissahickon deep into Philadelphia’s history. In William P.C. Barton’s 1818 flora of Philadelphia (“Compendium Florae Philadelphicae”; v. 2; p. 182), he calls this plant “Pinus canadensis” with a common name of “Hemlock Spruce”, and describes it as “A very large and fine tree. The boards and scantling made from its trunk are called hemlock timber. On the Wissahickon ; abundant. On the Schuylkill, often met with.” Additionally, in Ida Keller and Stewardson Brown’s 1905 Handbook of the Flora of Philadelphia and Vicinity, the hemlock is listed as being in “Philadelphia – Wissahickon.”
And there are collections of hemlocks in the herbarium of the Academy of Natural Sciences (PH) that also attest to its long presence in the Wissahickon. On the label of one of these collections, collected by Henry A. Lang on the 9th of April 1924, the label indicates: “Wissahickon Ravine, common”‘, thereby indicating that much like today, there was quite a bit of hemlock there in the early 20th century. There are other collections of hemlocks at PH – from J. Bernard Brinton, M.D. (a founding member of the Philadelphia Botanical Club), collected on the 23d of June 1889 (this label simply indicates “Wissahickon”, with no further details given); and from Edgar T. Wherry (who was a botany professor at the University of Pennsylvania, among many other things), collected the 2d of August 1945, when he clipped a branch from a “Small tree on steep rocky hillside, Wissahickon Creek ravine near Thomas Mill Road”.
Hemlocks are one of the characteristic trees of the Wissahickon, and have been for quite some time – however, the populations we see now have a different aspect compared to the ones that would have been here in centuries past. While the smaller size classes that were here in former times we most certainly still see today, the larger ones, the oldest hemlocks in the wetter areas, the ones that would have reached the sizes of the nephilim that were here in Wildman’s time in the 1930s, are no longer here.