Oakland Cemetery

In between Friends Hospital and Greenwood Cemetery, just a bit off Roosevelt Boulevard in Philadelphia, is Oakland Cemetery.  Friends Hospital, founded in 1813, is the oldest private psychiatric hospital in the US, and it also has a beautiful landscape – with its azaleas along the way down to Tacony Creek behind it, with its enormous American elm tucked away into a corner behind one of its buildings, and with the many other trees and flowers dotting and shading it throughout, it’s a surprising little refuge of calm and color in the city, as traffic along the Boulevard rushes by, just beyond the gates and fence of the hospital’s grounds.  If you go back behind the buildings and down that road that is lined with those azaleas that bloom in the spring, and you take a left turn at Tacony Creek, you’ll eventually get to Fishers Lane.  And if you then take a left there, you’ll get to Ramona Ave, and then, a bit more along, as you walk along Ramona, you’ll see Greenwood Cemetery on your right.

Greenwood Cemetery was, in centuries ago, the property of Benjamin Rush, physician, signer of the Declaration of Independence, and advocate of sugar maples and the maple syrup that can be derived therefrom.  Why was Dr. Rush an advocate of maple syrup?  This was in large part because he was an ardent abolitionist, and didn’t want Americans to be reliant upon sugar from West Indies’ sugar cane, which was reliant, in turn, on slave labor for its production.  There are, currently, some extraordinarily large sugar maples there, at Greenwood Cemetery, that stand as markers to Rush’s advocacy for their products, and for his advocacy for that most basic of human rights, the right to live freely.

In the post-Rush era, this site became a cemetery, Greenwood Cemetery, chartered in 1869, and as the years wore on, maintenance became difficult to keep up, and this place became quite overgrown, and up until recently was somewhat forested, but it has recently been restored and renovated, and is an idyllic spot to walk now.  And in addition to the sugar maples that I just mentioned, there is also an enormous American sycamore there, that based on its size looks to have been planted in the mid-19th century.  American sycamores don’t do very well in sooty air of cities, and so this tree suggests, to me at least, a 19th century habitat that was open and well stocked with clear air.

And in between these two landmarks, in between Friends Hospital and Greenwood Cemetery, is another open area – open amid the swaths of buildings and roads that pack in, through, and around Philadelphia, it is open and green with trees and shrubs and grass, an open space in the city – Oakland Cemetery.

According to the book Philadelphia: A Guide to the Nation’s Birthplace (by the Federal Writers’ Project, in 1937) Oakland Cemetery opened in 1881 (they also mention that it’s 43 acres), however, as I’ve been told by Jackie Childs, the official start date for the cemetery is 1891.   And Jackie is one to know such things – she is the fourth generation in her family to take care of Oakland Cemetery, and is wonderfully knowledgeable as to what is there, and also as to what was there before.

The cemetery was briefly known as Mt. Auburn (as is indicated on the 1895 map here: http://www.philageohistory.org/tiles/viewer/), but shortly thereafter came to its current name of Oakland (as is indicated on the 1910 map here: http://www.philageohistory.org/tiles/viewer/), and that is what we know it as now.

In 1895, electric lights were put in, as was recorded in the Journal of the Select Council of the City of Philadelphia, vol. 2 (from October 4, 1894 to March 28, 1895)


Locating electric lights for the year 1895.

Section 1. The Select and Common Councils of the City of Philadelphia do ordain, That the Director of the Department of Public Safety be, and is hereby, authorized and directed to erect electric lights on the following streets and avenues, viz. …”

Following that ellipsis, among the hundreds upon hundreds of streets noted as soon to be having electric lights, we find “south side Asylum pike opposite Oakland Cemetery” listed among them.

If you go there now, you won’t see those lights, but you will see trees that were in the cemetery at that time – at the entrance to Oakland at Adams and Ramona, for example, there is an enormous black oak (Quercus velutina) that, based on its size, I estimate to predate the cemetery.  Also, it has wide and broad spreading lower limbs – this indicates that it has been open grown since its youth, thereby providing evidence that this property was not forested, even prior to its conversion to a cemetery (it would have been a farm – and so we can put together a little story that this now majestic black oak would have, in the mid-19th century, been a scrawny little sapling that was kept alive with, quite likely, the intention of shading cows in a pasture, or farmers on break from working the fields, or the owners as they watched the workers working, perhaps).

Why do those wide and spreading limbs of the black oak indicate this history?  Well, when trees grow in the forest, with other trees nearby, those other trees shade out the lower limbs – and then those lower limbs become weak, and then they fall off, and so we get trees in the forest that are generally tall and straight, growing upwards, with relatively few lower limbs spreading out horizontally (and perhaps with a bit of the oblique).  However, absent those neighboring trees, being “open grown” that is, and absent someone coming along and cutting off a tree’s lower limbs, a tree will branch out broadly, low and spreading, and as the years go by those lower branches will get thicker and larger, expanding in girth as they expand in length, presenting an architecture that looks like it was made to be climbed on or climbed up.  The black oak at the entrance to Oakland Cemetery has just that aspect, and so we can say quite confidently that it didn’t grow up in the forest, but in a field.

If you go a bit farther in to the cemetery, up to the main house there, on your left is an old umbrella magnolia (Magnolia tripetala) – its main trunk has died back, but the suckers that have come up off the roots flower quite well, as the fruits that were there in September 2012 attest.  The umbrella magnolia isn’t native to southeastern Pennsylvania, though it is native to west of here, as Ann Rhoads very persuasively argued in Bartonia, the Journal of the Philadelphia Botanical Club, however it has grown here for quite some time and been naturalized for about a hundred years or so, and it is a reasonably common tree to see planted, or coming up in the woods (I see it pretty often up in the Wissahickon).  This one at Oakland, looking at the base that has died back and from which these suckers has arisen, is one of the largest that I’m aware of around here, and I wonder if it represents one of the earlier plantings of this tree around here.  I should say also that this tree has been growing in Philadelphia for over two hundred years – Magnolia tripetala is listed in the Landreth’s nursery catalog of 1811 [which can be found in the McLean Library of the Pennsylvania Horticultural Society], with a common name of “umbrella tree”, and it’s listed in John Bartram’s “Catalogue of American Trees, Shrubs and Herbacious Plants, most of which are now growing, and produce ripe Seed in John Bartram’s Garden, near Philadelphia. The Seed and Growing Plants of Which are disposed of on the most reasonable Terms.” ([Phila.]: [1783]), as is noted in Joel Fry’s article “An international catalogue of North American trees and shrubs; the Bartram broadside, 1783”, in the Journal of Garden History (vol. 16, no. 1, 1996).

A bit farther down and along, just past the house, you start to see large white ash (Fraxinus americana) trees, growing wide and spreading.  These trees, based on their size, I would estimate to have been planted around the time of the opening of the cemetery in the late 19th century – their placement along its paths also attests to their planting having postdated its establishment.  They also look to have been pollarded.  Pollarding is a process whereby the top of a tree is cut off, thereby allowing side shoots to grow up and out from where that top had been removed – this establishes a broadly arching habit, much like what one might see in an American elm, with branches stretching up and over, and if pollarded trees have been planted along side either side of a road or path, those upward sweeping limbs can meet in the middle, forming a vaulting architecture under which we may walk and cars may drive.  Of course, trees can also lose their tops without the intentional intervention of people, without pollarding that is, and so you have to check that this is part of the landscaping intentions, and isn’t due to wind, or someone accidentally swiping a top or two of a tree as they pass by with a truck or something.  These ash trees at Oakland are pretty much all spraying upwards from points at roughly the same height – this suggests to me that they were managed to look like this (if the breaks were accidental or due to nonhuman interventions, then I’d expect them to be expanding outwards from different heights), suggesting that they were clipped so that they could go on to form graceful ceilings under which mourners could make their ways to gravesites, and also so that Sunday visitors who simply wanted to visit a beautiful park could stroll underneath a sky of green.

Onwards and somewhat southwards, as you go along the path that goes towards Ramona Ave and Fisher Lane, and as you get nearly towards the split point of Ramona and Fisher, you’ll look down on your left and you’ll see a sewer.  I was pretty excited when I saw that for the first time – why was that?  Why was I excited to see this hole in the ground, a hole that pretty much just leads to other holes?  Why on earth (or in earth) would I get excited to see a sewer?

Well, if you look at old maps of this site you’ll find that there were streams that used to run through it – in the 1862 map here: http://www.philageohistory.org/tiles/viewer/, you’ll see a couple of streams running out of the back of what is now Oakland Cemetery, and one of them, the one to the south, was roughly where Fisher’s Lane splits off from Ramona Ave (and also running along Ramona a bit prior to Ramona’s split with Fisher); the other was up towards the Friends Asylum. The former stream (the one running near what is now Ramona and Fisher) is not on the 1855 map (here: http://www.philageohistory.org/tiles/viewer/); the latter is.  If we look on the 1843 map here: http://www.philageohistory.org/tiles/viewer/), both streams are on map, and on the 1808 Hills map (same place as the others), the southern (the one near Ramona and Fisher) stream is there.

There is, I should say, another sewer uphill from that old one – it is newer, and while it does, I’m quite confident, pour its water and other effluvia ultimately into that old streambed marked in those old maps, because it is newer it is not as likely to mark quite as exactly where the stream ran, like that old one does, but was more likely constructed as simple drainage for the road that it accompanies.

And so, that old sewer, and a pretty humble one at that, unlabelled and unadorned, marks the site of a stream that is no longer there – it gives us a physical landmark with which we can pinpoint where that historic stream was, a stream that was limned on old maps and has since been covered up but still carries water, though now underground.  A stream that ran when Benjamin Rush lived here, advocating for abolition, a stream that ran when Friends Hospital opened, a hospital devoted to humane treatment of those who had been treated quite differently prior to that, a stream that ran when this site, Oakland Cemetery, was farmland, with a little black oak seedling far a ways up the hill, now shading the entrance to this city of the dead, but then kept alive most likely with the intention of shading pasture for farm animals, or farm workers, or farm owners – this stream still runs, but the only evidence we see that remains is that humble opening, telling us, quietly, subtly, discreetly, where the history lies beneath.

To read about the importance of cemeteries to urban planning, see here:


To read about some more natural history and open areas, including cemeteries, nearby – see here:


Cedar Grove

Hunting Park

Monument Cemetery

Some Plants and Insects of the Woodlands

A different zelkova (Woodlands Cemetery)

Feral landscaping (Woodlands and Mt. Moriah cemeteries)


Basal scars on street trees

If you walk along Pine Street in downtown Philadelphia, from 7th Street to 6th Street, you’ll see a number of trees planted there: various species, of various sizes and ages – with different kinds of leaves and bark, and different kinds of fruits and flowers and seeds – there’s a nice little bit of diversity along that city block, in a number of different kinds of ways, many of which are characteristics of diversity that are commonly noted when people look at trees in cities.  But there is also another kind of variability in the trees on that block of Pine Street, a kind that we don’t often think of when we look at urban trees, and that variability is in the basal scars.

What are basal scars?  Well, as Tom Wessels sagely defines them in his book Forest Forensics, they are “scars at the base of tree trunks created by the removal of bark from fire or some form of impact”.   Basically, they are areas of a tree, towards the base, where the bark was once stripped away and you can see directly to the wood that had been underneath that bark, and the bark has grown up scar tissue around the sides of the wound.

Why does Tom Wessels define them in his book?  Well, in Forest Forensics, as well as an earlier book of his, Reading the Forested Landscape, he discusses how basal scars can be created, and therefore how they (basal scars, that is) can be used to interpret prior land use history.  For example, if there are trees growing on a slope, and there are basal scars on the uphill sides of the bases of those trees, this implies that there was a forest fire there at some point.   Why is this?  As Mr. Wessels explains, the uphill side of a tree trunk is an excellent tool for catching sticks and twigs and leaves as they tumble down a hill – to a botanist, these are plant parts, but to a forester, however, especially one interested in fire ecology, this is debris that is fuel for fires.  And as this debris, this fuel, is piled up against the trunk, and moreso on the uphill side, then that uphill side will generally burn hotter than the other sides of the trunk – and possibly hot enough to burn away the bark, and then to leave a scar.  Therefore, scars on the uphill sides of trees on a slope implies a forest fire at some point in their history.

A certain basal scar orientation can also imply logging – if there are basal scars that are facing each other, that is, if trees that face each other have basal scars directly across from each other, this implies a logging history.  Why is this?  Again, as Mr. Wessels explains, when loggers were dragging out logs from trees they had cut down, they would have taken them along logging roads, and since trees are frequently found in forests, one might expect that there would be trees on either side of those logging roads.  And, since those cut logs would quite likely have bumped up against those trees on either side of a road, well, one would then expect logging to cause there to be basal scars on trees on either sides of logging roads, and therefore opposing basal scars are considered one line of evidence to support a history of logging in a forest stand.

OK, so on Pine Street between 6th and 7th Street, in downtown Philadelphia, there has not been logging any time recently, and so these basal scars are most likely not from some Philadelphian Paul Bunyan’s lugging of logs through the city streets.  And, while there may well be house fires on that block with a reasonable frequency, those fires are unlikely to spill onto the street, and therefore unlikely to scar the trees there.

So what is it?  What left those scars?  Vandals?  Construction workers as they build or mend houses and accidentally bump into the trees with their equipment?  Cars as they drive down the street and occasionally veer onto the sidewalk?  Car doors as they let people out?    Errant bicyclists careening into arboreal blockades?  Which of these is it?

Let’s look at the evidence…

As one walks east from 7th Street, towards 6th, one sees first a willow oak, and then another one – that first one has a pretty large scar on it, on the west side of the tree; the second does not have any major scarring.  The next tree is an elm, somewhat small (less then 3″ dbh [=diameter at breast height]), with no scars, and then the next tree is a sweetgum, with a scar on the west side of the tree.  This is followed (going eastward), by two Norway maples, both with no scars, and then these two are followed by a Norway maple with a scar on the street side of the trunk of the tree.  This is followed by a ginkgo with a street side scar, and then finally, right up towards 6th Street, there is a sweet gum with a mild scar (not so strong that one can see through to the wood, but a noticeable change in the texture of the bark), and that light scar faces roughly westward, and is somewhat angled towards the street.
If we then walk back towards 7th, from 6th Street, the first two trees we see are sweet gums without any scarring, followed by a London plane with a pretty big scar facing towards the street, and another scar facing east.  This eastward facing scar is at the end of a stumpy branch; it is not on the main trunk of the tree.  After that somewhat mangled London plane, as we go westward now, there is a sweet gum without a scar, followed by a somewhat small London plane (less than 10″ dbh), also without scarring.  The last two trees on the block, before we get to 7th Street, are both willow oaks, and neither have scars.

There is only one tree with scarring on the east side, and that one is the London Plane whose scar looks to have been derived from a branch having broken off (this is because the stump of that branch is still there, providing evidence of its own existence).  All the other scars are either on the west sides of the tree trunks, or facing in to the street.

Of 16 trees on this block, none of them have damage directly on their trunks on their east sides, nor on the sides facing in to their respective sidewalks.  Two of them have basal scars on their west sides, three of them have damage on the street side, and one of them has evidence of light damage at an angle between the street side and the west side.

Traffic goes east on Pine Street, and north on 7th Street – therefore, it makes sense to me to come to the conclusion that the westward facing scars are from cars running into the trees.  The one eastward facing scar, the one that would have come from a broken branch, doesn’t disagree with this pattern, I think, and I’ll get back to that in a minute (depending on how fast you read, that is).  The tree on the southeast corner of 7th and Pine would be especially vulnerable, as someone making a turn there could easily hop the sidewalk and run right into that willow oak there.

The street facing scars are most likely from car doors – and not just any car doors, but more often from passenger side car doors than drivers’ sides.  Note that there are two street side scars (possibly three, if we count the faint one on the sweetgum) on the south side of the street, which is the right side (= passenger side) of the street in the direction one would be driving on this block, while there is only one street side scar on north side of the street, and that one on the north side is accompanied by evidence of a broken branch, and a relatively large branch it is (it’s over an inch across), which implies that the strike that did this had some force to it – perhaps more than an opening door would have caused, and perhaps more likely from it having been sideswiped by a car.  This broken-branch line of evidence also suggests that, as I mentioned above, the eastward facing scar on this London plane doesn’t disagree with the idea that basal scars here are due to collisions with cars coming from the west – breaking off that branch could easily have happened from a collision from a car coming from the branch’s opposite side and snagging that low lying branch right off (it’s only a foot or so off the ground).

But back to the car doors for a moment – one would expect there to be more damage from passenger side doors than driver side doors simply because the driver can see out his-or-her side more easily than that of the passenger’s, and so would be more likely to avoid hitting a tree with their own door, while a passenger would be more likely to pop out the door and, inadvertently, hit a tree with it as it swings out.  And so our evidence fits what makes sense, which doesn’t always happen, and so I like to point out when it does.

To summarize a bit here –  the evidence strongly suggests that these basal scars are from cars colliding with the trees, and also from passenger side doors hitting them (hitting the trees, that is).  If these scars were from vandals or sturdy bicyclists, I’d expect there to be scars on all sides of the trees.  There are not.  And if these scars were from construction or maintenance of the houses on this street leading to tree damage, I’d expect there to be scars on the sidewalk side of the trees.  There are not.  And so, it appears as though the main source of damage to these trees is cars.

This is only one city block of course, and it will be interesting to see if this pattern holds elsewhere.  It also would be interesting to see if we can find evidence of traffic direction changes, etched in the scars of street trees – for example, if a street’s traffic direction changed, but its trees did not, we would expect to see some scarring on the older trees on the opposite side of current oncoming traffic.  Or if there’s places where we might see evidence of a street getting changed from a two-way to a one-way street – older trees would mark the past all the way up to today, the current trees would only record the present and the more recent past.  Or, looking forward, as more bike lanes are put in place, for example as we now have in the south lane of Pine Street (including between 6th Street and 7th Street, the area we’re talking about here), maybe there will be fewer passenger side door bumpings with trees, and we’ll see a reduction in street side basal scars where bike lanes are put in.  Or perhaps we won’t.  One never knows, but eventually we will, if we keep on looking.