By Tim Clancy, for Let’s Talk Plants! January 2023.
Do You See What I See?
One of the fabulous perks of living in Southern California is the variety of trees available for us to study and admire. In the course of daily living many of our actions become so routine they are almost automatic. Have you ever gone somewhere, say to the local bodega, only to realize that you don’t really remember the trip? You have made the journey so many times that your mind is able to wander as you roam with a purpose.
Sure, we see the silhouettes of trees as we go about our business. In many cases the outline alone is enough to identify the species. This can even be done while driving 75 mph on the freeway. Sycamores, eucalyptus and many pines are easy to spot. Sycamores with their tell-tale bark coloration can easily be identified both in and out of leaf.
For those of us with a little more time and curiosity, there is so much more to be seen when looking at the trees around San Diego. Tree bark is a fascinating tree part. The job of bark is to protect the business part of the tree (where new wood is made) and regulate gas exchange. Bark is generally impenetrable by these gases, so the answer is an opening called a lenticel. You cannot see these while driving on the freeway and some are only observable with a hand lens, but many can be seen with the naked eye upon close examination. So, the bark, which protects the tree and is full of holes which, if magnified, would be reminiscent Swiss cheese.
Leaves come in all shapes and sizes and are a great source of knowledge about tree viability. You can look at both the leaves on a tree and the leaves that have fallen. Each year in Southern California Sycamore leaves play host to both powdery mildew and anthracnose, both of which have easily identified distinct characteristics and both of which affect the leaves in their own way. Next time you see a recently fallen Sycamore leaf on the ground stop and pick it up. Have a close look. I use my phone light and magnifier to get a better look.
Fuzzy magnolia flower buds, flowers shaped like cups, flowers that follow the sun, leaves all shaped in such a manner to capture sunlight and, through the miracle of photosynthesis, make food for survival, branches jockeying for position, so they have a long a productive life. Some of the early branches are sacrificed to shade as the tree constructs its optimal shape.
Many of our trees are home to all sorts of interesting creatures. If you have ever found yourself brushing off ants after leaning on a tree you know what I mean. If you look close enough you can see a very necessary, business-like operation, with thousands of ants working in cooperation to clear out aphid honeydew. If left in the tree, honeydew, the byproduct of the aphids, would interrupt the gas exchange process because it plugs up the lenticels.
Next time you find yourself with a few moments, Stop and smell (and look at closely) the trees!
