Maybe you believe toward the end of October the wall between the dead and the living weakens a bit — a fine reason to hang out in a cemetery. Maybe you love autumn. The landscape of orderly stone, soft grass and falling leaves is the perfect place to enjoy the season. And maybe, like me, you figure this is a fine time to search for your own dead and see what might be living above them.
Thus, I dragged my dad out of Center City to Har Nebo Cemetery in Oxford Circle to help me find his grandparents. I was fascinated by the journey into my family history, of course, but I was also looking for lichen on their headstones. The cemetery manager had given me what sounded like clear directions as to their whereabouts, but I couldn’t find their final resting spots. My dad and I separated and went stone to stone.
We might think of corpses as dead, but if left alone, they’ll quickly be pulled back into the living world by scavengers and decomposers. It is the tombstones that are truly dead. That is until the lichen show up, gripping the rock and growing outwards a millimeter or two per year.
Even as they turn dead spaces into gardens, lichen themselves break down the lines between organisms as we commonly think of them. That humble patch of green on the stone is a “composite organism,” aunion between a fungus and algae. The fungus builds a structure in which the algae can safely convert the sunlight to energy, all the while embracing the cells of algae in microscopic filaments— hyphae — that draw off nutrients for food.
This partnership can make some unusual procreation. Sometimes the fungi break off with their algae partners to set up shop on a new stone together. Other times, as Dr. David Hewitt, Research Associate with the Academy of Natural Sciences, explains, the fungi build what are essentially little cannons (visible as little circles with dark centers) to fire their spores into the world where they’ll hope to land on a proper blank surface and meet up with the right algae. “The sex is easy,” Hewitt says. “It’s building the house that’s the hard part.”
On another cemetery expedition, to the majestic Laurel Hill, overlooking the Schuylkill River, photographer Jen Britton and I weren’t looking for any graves in particular. Patches of lichen on weathered, barely legible headstones were everywhere: leafy Physcia [Figure 1-3], chartreuse Candelaria [Figure 4] and powdery gray Lecanura growing into the stone and rising a mighty distance (for a lichen that’s a couple millimeters) above to send their spores out into the great beyond.
Back at Har Nebo, I found lichen on other grave markers, but my great-grandparents’, when my dad finally spotted them, were clean, shiny and sterile. I’m not sure how long it will take the marble to weather enough to give some tiny spore a home, but I’ll look forward to them coming back to life some other October.
Bernard Brown is an amateur field herper, bureaucrat and founder of the PB&J Campaign, a movement focused on the benefits of eating lower on the food chain.
Laurel Hill Cemetery has a busy calendar of events. Visit them online to see what’s going on.