LET’S HEAR IT FOR TREES
By JIM NICHOLS
The two trees are rather like twins in many ways. They stand next to one another, separated by perhaps thirty feet. One of the trees is on the edge of our yard and the other is across our neighbor’s driveway in about the center of their front yard. Judging from the similar ages of our two houses, it is reasonable that the trees were planted at about the same time. With a parallel amount of modest trimming over the years, they are about the same height and fullness. They look very much alike.
There are two times of the year in which they obviously differ, however. In the spring, each of the trees produces vivid white flowers. Interestingly, the neighbor’s tree produces blossoms about a week before ours does. In neither case do the blossoms last long, especially in the windy springtime. In the first years of living there, we assumed the different time of flowering was just an oddity, but now we understand that the trees, though similar in many ways, are also different.
The difference appears also in the fall. During this time, the leaves become brightly multi-colored. Yellow, orange, and red leaves replace the green ones as the chlorophyll degrades and the other background colors become evident. Again, however, the neighbor’s tree has a color change that precedes ours by at least a week. Sometimes there is another consequence of this timing because in the short time period between the two trees’ changing, a deep freeze occurs. That has happened this year. Unfortunately, this freeze apparently caught our tree’s leaves before the color change. The result has been a disappointing movement from originally green straight to brown and dry.
This tree consideration has touched my biology background. Biology instructors struggle to interest students in plants; animals is what they want to study, especially humans—especially blood and guts, frankly. As a class probes various forms of life, however, it becomes apparent that, although plants cannot speak to one another as animals do, they can communicate. Furthermore, they do so in often-complicated ways. This communication involves the wind frequently.
Insects can carry pollen produced by male parts to receptive female parts, but it is also reliably carried in the wind. Those of us with seasonal allergies are witnesses to the presence of this pollen.
Pheromones are hormone-like chemicals that play a powerful role in communication in both animals and plants. Produced in incredibly minute amounts and distributed by the wind, these substances are major drivers of many organism activities. Although best studied in animals, there are fascinating examples in plants also, including trees. In one particular type, when a certain insect invades an individual tree, the tree produces an “alarm” pheromone. Just a few molecules carried downwind cause a neighbor tree to produce defensive chemicals to the insect. This process becomes a benefit to the whole grove of trees in mutual defense.
Underground communication between trees is also common. In some cases, fungi form bridges between roots of different trees to allow the exchange of nutrients; one author identified this as a “Robin Hood” approach where the rich give to the poor. Speaking of roots, aspen trees in a grove appear to be individuals. In fact, if we could see beneath the ground, we would realize that what we see above ground is really offshoots of a complex common root system. Indeed, a grove of aspen trees is actually only a single organism with multiple pieces.
People who count things report that trees are the second most common living organism in scripture; humans (and God) are first. It is difficult to read the Bible and not encounter references to trees frequently. Some of these are trivial mentions, but others are parts of main stories. For instance, when Jesus is healing a blind man in steps, the man initially reports that he sees “. . . men walking like trees.” Where was Zacchaeus when Jesus called him? In a tree. Often in scripture, rather than using the word “cross,” the word “tree” is used. The theology of grafting followers of Christ onto Israel’s trunk is fundamental. We see trees in very early Genesis and in the last chapter of Revelation; one could make the case that trees form the bookends of what we call scripture.
When I see the trees in my yard and elsewhere, I am struck by this theme that God has chosen for some reason. The trees represent creativity and variety, color and flexibility. In some ways, they are alike, but in others, they are different. They supply shade and protection, food and stability. They are present at the beginning of God’s story and will be present at the end.
“. . . blessed is the one who is like a tree planted by streams of water, yielding its fruit in its season. . . “ (Psalm 1:3)
Jim Nichols is a retired Abilene Christian University biology professor and current medical chaplain.