Aristolochia californica, the California Pipevine, is a member of what may be one of the earliest groups of plants, the paleoherbs. The flower is composed of sepals fused into a calyx tube shaped like a calabash pipe. Before the leaves appear, the flowers form as miniature "pipes" only a fraction of a centimeter long. They continue to grow larger until reaching a final size of 2 to 4 centimeters. Thus you might notice flowers of different sizes on the same plant, as in the picture to the left. It is unusual to see flowers "grow up" in this way. In most other kinds of wildflowers, the showy part of the flower consists of petals that have reached their full size before emerging from their enclosing sepals. The fruit of the pipevine is a 6-winged capsule 2-1/2 to 6 centimeters in length.
The pipevine flower produces a foul odor which attracts
fungus gnats. Once they enter the flower through the "bowl" of the
pipe, the fungus gnats are trapped inside for a long
enough time to increase the chance of pollination. This has led to the
misconception that the Pipevine is an insectivorous plant.
The Pipevine Swallowtail butterfly lays its eggs exclusively on Aristolochia species.
The larval stage, or caterpillar, uses this
plant for food. The Pipevine contains a toxic chemical which is ingested by the Pipevine
Swallowtail caterpillar, rendering it and the subsequent butterfly
unpalatable to birds. When you find a Pipevine in leaf, look for small reddish eggs or, later,
black caterpillars methodically munching away on the leaves.
Young caterpillars will be quite tiny, so look closely.
Caterpillars also relish the fruit of the Pipevine as can be seen in the photograph
of the fruit (above).
California Pipevine can be seen just inside the entrance to Samuel P. Taylor State Park,
growing on the trees and shrubs just to the right after you pass the entrance kiosk.
Another good place to see it is Cascade Canyon Open Space in Fairfax. In April watch for Pipevine Swallowtail Butterflies. If you see a number of
these butterflies, it is quite likely that California Pipevine is growing in the
vicinity. While Pipevine Swallowtail Butterflies sip the nectar of other flowers, they will lay their
eggs only on this plant. California Pipevine is widely distributed in Marin County. The first specimen of
this species of Aristolochia to be described was found by the botanist
John Milton Bigelow in Corte Madera, Marin County.
Aristolochia californica grows in California along streamsides and in low wooded hills. It is found in the Coast Ranges from Monterey County north to Mt. Shasta, in the Sacramento Valley, and in the northern Sierra Nevada foothills.
In the Marin Flora, John Thomas Howell lists its locations as Angel Island;
Sausalito Hills; Phoenix Lake and Bootjack, Mt. Tamalpais; Fairfax Hills; San Rafael;
Lagunitas Creek.
In A Flora of Sonoma County, Catherine Best et al. list its
locations as Neeley Hill area near Guerneville; Forest Hills 5-1/2 mi e. of Guerneville;
Russian River opposite Vacation Beach; Bouverie; Sonoma Cr. at base of Mt. Hood; Sugarloaf
Ridge; Santa Rosa; Leslie Road near Mark West Springs; Pepperwood; Healdsburg quad.
In the Flora of the Santa Cruz Mountains of California, John Hunter Thomas lists its
locations as "known definitely from Lake Merced in San Francisco and reported from other
parts of the Santa Cruz Mountains."
You can view a distribution map like the one shown here for any plant included in The Jepson Manual by going to the web site maintained by the Jepson Herbarium.
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