It’s Summer Book Week at Via Negativa. Since I’ll be gone part of the week on vacation myself, I decided it would be an ideal time to consider what constitutes the perfect summer read. I’ve enlisted the help of my family to put up posts while I’m gone, and even do a little guest-blogging.
I can’t very well review my own mother’s book. Who would trust such obvious nepotism? On the other hand, Mom has included poems of mine in the front matter of three out of four books in her popular Appalachian Seasons series, so I think it’s high time I return the nepotistic favor. Since the books are blog-like journals anyway, the obvious thing to do here is simply to reproduce an entry from Appalachian Summer as a substitute blog post. Enjoy.
JULY 25. Most of the field wildflowers provide food for other creatures. This morning I watched a male American goldfinch feed on dame’s rocket seed. Bouncing bet attracted silver-spotted skippers and a black swallowtail butterfly while Joe Pye weed appealed to great-spangled fritillaries.
Then I encountered a patch of golden-yellow, common St. John’s wort (Hypericum perfolatum), an immigrant species that thrives in fields. It seemed to be devoid of feeding insects. Most insects avoid St. John’s wort because it emits a toxic chemical called hypericin, hence its genus name. Hypericin is made and stored in the leaves, flowers, and stem glands of St. John’s wort and slowly poisons a predator.
However, it depends on sunlight to activate it so some insects can avoid its toxicity by clever ruses. Butterfly of moth larvae that roll or fold a leaf and bind it with silk to cover themselves or sew leaves to form a shelter can eat St. John’s wort from within because they are shielded from sunlight. Stem borers and leaf miners are also protected from the sun. The tough outer layer of several adult beetles in the genus Chrysolina screen out sunlight. The soft-bodied larvae of Chrysolina hyperici can eat inside the leaf buds of St. John’s wort or feed openly on the plants only at dawn. In addition, they contain a large amount of beta carotene that combats phototoxicity. So, no matter how much a plant evolves to resist predators, there are always a few that can circumvent their prey’s resistance.
Humans have recently been taking St. John’s wort to fight mild depression. They too must stay out of the sun to avoid triggering hypericin. This seems counterproductive to me. I would become even more depressed if I were forced to stay inside. It is the bright sunshine that continually elevates my spirits. After a succession of gloomy, overcast days, my mood matches the weather. Only sunshine cures my depression. Yet so many people spend most of their lives inside under artificial light even in the summer. Perhaps those with mild depression would benefit from frequent walks in the sunlight, especially on such a spectacular day as this one.
– Marcia Bonta, Appalachian Summer