Observation, natural history, and an early post-Darwinian view of plant-animal interactions.

In 1887, an American botanist, James, published an article on his fascination with milkweeds in The American Naturalist (James 1887), becoming one of the first in a long line of plant ecologists who seem to be in love with latex— walking around, breaking leaves, rubbing the sticky, sometimes smelly viscous plant exudate between their fingers. And why not love latex? It is often hard to visualize a plant’s defensive tactic, but here is a trait that occurs in nearly 10% of plant species, has independently evolved many times (there are even the latex-bearing mushrooms, Lactarius spp.), and seems to have little function other than defense. Latex can therefore serve as a model for understanding the evolution and ecology of many defenseoffense interactions. In 1887, James used his observations on the milkweed’s latex, herbivory, and pollination, combined with the latest in Darwinian thought, to frame his thinking about plant-animal interactions. Reading this article now offers us remarkable insight into the power of observation and natural history in developing conceptual ideas about an organism’s whole ecology, an ideal advanced early on by The American Naturalist.