Along a scrub-covered river bank, a leafless alder is draped in a leafless, flowering vine. This is the California pipevine (Aristolochia californica)–a showy early bloomer, that can be surprisingly hard to spot. When viewed up close, it is striking. The distinctive pipe shape is nearly two inches long, with brick red petal lips and veins streaking the bent green tube of the flower. It just needs a pair of googly eyes perched on top to become a goofy puppet a la Sesame Street. One would think this would be hard to miss–and yet in its leafless stage, pipevine flowers camouflage nicely with the brown leaves and spring buds of our winter forest, and one can (and I certainly have) walked right past it without noticing. As the season advances and the vine’s bright green, heart-shaped leaves emerge it becomes easier to see.
California pipevine, also known as Dutchmans pipe, is the only food for the caterpillars of the beautiful, iridescent-black pipevine swallowtail butterfly. The vine contains toxic compounds which don’t harm the caterpillars, but render them toxic to predators–a benefit which lasts throughout the pupal and butterfly stages as well. Mature pipevine swallowtails are often seen fluttering around this plant, where they lay their eggs; in fact, following one of these butterflies has led me to a nearby, unobtrusive pipevine plant that I otherwise would not have noticed!
The musty-smelling bloom itself is very attractive to flies and gnats, and fungus gnats are thought to be one of its prime pollinators. The pollination process is vividly described on this Putah Creek Council blog post: “Guided by stiff hairs, the insects are directed into the convoluted flowers, picking up pollen as they seek a way to exit. Eventually the flower hairs relax and the pollen-covered gnats are able to escape and spread pollen to other plants.”
This is the only pipevine species in California, but there are numerous species worldwide.