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 Bruce W Leander

FLORA: NATIVE POLLINATOR PLANTS

Swanflower Hosts Pipevine Swallowtails

The poetically named swanflower is difficult to distinguish from other wild green foliage on most days. Sometimes, though, this diminutive host plant for the pipevine swallowtail stands out from the others when a horde of knobby orange caterpillars emerges from eggs to feast on it.

Pipevine swallowtails are medium-sized butterflies that look black from a distance. On closer examination, the hind wings are iridescent blue on top and blue speckled with orange on the flipside. They have retractable horn-like organs on their heads.

Unlike the colorful, showy flowers of other plants that attract pollinators, the swanflower (Aristolochia erecta) starts as a twisted spear of a bud, then opens up an otherworldly, orchid-like, burgundy bloom with white spots. It looks like family to East Texas carnivorous plants, and it is.

This Texas native’s bloom sits upright (“erecta”) and curved like a swan’s neck, displaying these flowers from April through October. The swanflower seedpod, or capsule, is about three-quarters of an inch long and contains flat black seeds.

The Aristolochia family is also known as birthwort, due to the unusual shape (like reproductive organs) and historical use to aid in childbirth. Some contain a toxin that butterflies can tolerate but makes them taste bad to predators.

One species from the Aristolochia family is actually deadly to the pipevine swallowtail. Pelican or calico flower (A. gigantea), also known as giant Dutchman’s pipe, features a huge, unusual bloom. It’s originally from South America, where there are no pipevines. When cultivated in gardens here, the plant proves toxic to the pipevine larvae, which die a few days after feeding on it.

Swanflower seeds can sometimes be found at native plant nurseries; the long, tubular root makes it difficult to successfully transplant from the wild.



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