The School of Trees

I am attracted to plant life. The sight of a restaurant or bar repels me, but the sights of bush or the promises of a nursery, fill me with excitement. And there is more to plants than mere inspiration. Plants respond to threat--often with volatile carbon compounds -- phenols, alkaloids, and terpenes -- entrapping or irritating invaders.

The emitted chemicals are like cries of help, or like roars of intimidation. The volatile chemicals go airborne, and so reveal the dining caterpillar to the female dragon fly sniffing for a fat host to inject with her eggs. Surrounding plants often become more resistant to herbivore assaults, apparently tuning in to the message of the focal victim.

When a cruciform detects the presence of flutterby eggs on its leaves, glued on by benzyl cyanide, the plant detects the additive, and swiftly secretes ovicides, extrudes a carpet of neoplasms to push the eggs off, and issues attractants to wasps who prey upon caterpillars.

However, plants are not all ethical autotrophs wresting food from the sun, while surrounded by us animals who must kill to live. The parasitic dodder, related to morning glory vines, can detect the secretions of its favored host, the tomato. The seedlings grow toward the host, with the intention of encircling the stem and sucking its phloem unto death.

Nor is the iron needle clutch of the chonta palm, or the thorn in the bougainvillea bower and the rose bush, a mere inadvertency. The sting of the nestle, the scarlet scourge of the poison oak, these are not "unintended" -- Plants go to great care to produce "lessons" for other life forms in the environment.