My first experience with tulip poplar trees (Liriodendron tulipifera) made a lasting impression on me, but I had no idea then that it was the beginning of a long relationship. Back in the days when fourth-graders could hang out without parental supervision, my best buddy and I were practicing to be circus performers, specifically tightrope walkers. Our tightrope was a metal cable hung between wooden posts. The cable was not there to foster juvenile circus fantasies; it had been installed by the highway department to keep cars from spilling down the steep, wooded hillside. While awaiting my turn on the high wire, I looked down at the ground and saw a tuliplike flower with green and orange petals. I had no idea where this beautiful flower had come from until I looked up into the trees overhead and noticed other flowers like it there. Tulips that grew on trees! How magical!
I sometimes ask others about their childhood memories of plants. It turns out that many people have a very specific memory of a particular plant species, a memory of wonder, awareness, connection— sometimes almost to the point of fear. If you carry such a memory, you have probably tried to learn (though perhaps years later) the name of the plant that held you spellbound. I learned that my beautiful flower came from a tulip poplar tree. Some books call it a yellow poplar, but it will always be a tulip poplar to me.
AS FATE WOULD HAVE IT, I renewed my acquaintance with that species years later when I was an undergraduate studying the fungal diseases of plants. My faculty adviser was interested in a fungal disease of tulip poplar trees, and I found myself doing a scientific research project, my first, on Liriodendron tulipifera. I learned that a fungus named Verticillium can enter the tree roots and cause a disease that eventually kills the tree, either by physically blocking the water passageways or by producing a toxin. Our research project was designed to discover which of these two mechanisms was responsible for the tree’s death.
After months of work in the laboratory I determined that the wilt was caused by a toxin. The procedure to purify the toxin involved a lot of glassware and drop-by-drop precision. By the time I got the toxin purified it was time to graduate, so I wrote up my senior thesis: “Isolation of a Lipoprotein from Culture Filtrates of Verticillium alboatrum.” It was my first taste of real science, and among other things it taught me that I was better suited to field biology than laboratory research.
Be careful what you wish for. My most recent experience with a tulip poplar tree was sleeping in the top of one! You have probably heard of tree sitters: people who live for a time in the treetops to prevent a forest from being cut. The tactic has been used a number of times, and sometimes it is successful. But how do you practice to be a tree sitter? How do you learn the techniques and decide if tree sitting is really for you? The best-known tree sitter of them all, Julia Butterfly Hill, began without any practice whatsoever. The first time she climbed up a redwood tree she was participating in a protest; the second time up she stayed for two years—protecting the tree’s life with her own.1 For the more cautious among us there is the Eastern Forest Defense Action Camp.
Summer camp for radicals seemed the perfect antidote to the heart-crunching pain I felt driving by yet another clear-cut forest every week. At the camp a guerrilla activist half my age taught me how to climb trees using ropes and a harness. She and her friends had rigged a piece of board, about the size of a door, sixty feet up in a tall tulip poplar tree. After I proved myself capable of the climb she asked if I wanted to try spending the night up there. Yes, please. When I climbed up to the small platform in the dark, hauling my water bottle and sleeping bag up behind me, I wasn’t expecting to get much sleep. I had to wear my harness at all times, complete with carabiners and ropes, and clip in to a rope tied around the tree to make sure I didn’t roll off the platform and fall to my death. Sleeping in a tree gives a whole new dimension to falling out of bed. As uncomfortable as it sounds, I was happy to be “clipped in,” and to my astonishment I fell right to sleep. I woke once in the night and got to experience the sounds of the nocturnal canopy—the flying squirrels moving from branch to branch and chirping to each other. It was much more blissful than frightening, and when I woke at dawn I was happy to see that I was still up in the tree. Up where the flowers are.
TULIP POPLARS have big, showy flowers—the ones that amazed me in my childhood— to attract pollinators. The flowers have to be pollinated within twenty-four hours after opening or no seeds will form. Insects carry the pollen from one flower to another. If there are no other tulip poplar trees nearby, the insects can self-pollinate the flowers, but self-pollinated flowers do not produce as many seeds, and the resulting seedlings are not as vigorous.
The abundant nectar produced by the flowers rewards the pollinating bees, and also the humans lucky enough to find the tulip poplar honey made by the bees. The trees must grow for almost twenty years before they reach “puberty” and begin flowering, but once they do they can produce flowers for another two hundred years. Each flower produces only about ten good seeds. The seeds, winged at one end, flutter to the forest floor in the fall and stay, alive but dormant, waiting up to seven years for an opportunity to sprout— that is, if the birds and squirrels don’t eat them first. Cardinals, in particular, are fond of tulip poplar seeds, and they gather beneath the trees, sifting the soil with their beaks as they look for the tasty morsels.
Tulip poplar seedlings are easy to start. All you have to do is go to a forest where tulip poplars grow, scoop up some soil from the forest floor, spread it in a shallow tray, and put the tray in a spot where it will get some light and you will remember to keep it moist. The seedlings are a favorite nibble for rabbits and deer, so be sure to put your seedlings in a place where animals cannot get to them. Food for bees, humans, cardinals, squirrels, rabbits, and deer— to name just a few—these trees are more than just wood.
These are the connections that interest me now: from sun to leaf cell to nectar to seed to bee to bird to me, an ecologist. The word ecologist comes from the Greek word for “house.” And I am striving to learn all that I can about this house, this home, of mine. It is a humbling task. There is much to learn. Charles Bowden, another forest ecologist, described the feeling in his book The Secret Forest:
I sensed I had wandered into that house we call ecology, a
place that pretends to be carefully mapped but always turns
out to be a labyrinth. The structure may have an edge but
it seems to have no center. The forest is a question that we
will never answer.2
Come wander through the forest labyrinth with me, and we will take a lesson from another ecologist that Bowden wrote about:
But Gentry was too alert and too alive to keep a single
focus and things besides the taxonomy of the forest
continually spill into his writings. He never let his love
of plants blind him to his love of life. Nor should anyone
else who wishes truly to savor the elements that lurk in
that single English word, place.3