Butterfly gardening is a popular pastime in North Texas. In our ardor to provide sustenance, however, we may be serving up a deadly dish unwittingly.
The iridescent black-and-blue pipevine swallowtail (Battus philenor) uses various species of pipevines as host plants for its eggs. Not every pipevine is an acceptable food choice and, unfortunately, the one species of pipevine that is most commonly sold in nurseries is deadly to the caterpillars of the pipevine swallowtail.
Pelican flower, also known as calico flower or giant Dutchman's pipe (Aristolochia gigantea), produces a bizarre, fragrant flower that appeals to gardeners because its bloom is so unusual. It is native to South America, where the pipevine swallowtail does not fly. Therefore, while female butterflies get proper chemical cues from the plant to deposit eggs on its tendrils and leaves, the plant is too toxic for the larvae, and they die after feeding for a few days. Unfortunately, many retailers market the plant as one "for the butterflies."
Another non-native, but safe, pipevine that occasionally is found at area nurseries is white-veined Dutchman's pipevine (A. fimbriata). The growth habit of this vine is more akin to a ground cover, and it has no twining ability whatsoever. The slightly pungent, heart-shaped leaves are about 3 inches wide and laced with pale green along the veins.
If you find it, buy several plants; the voracious pipevine caterpillars will eat it to the ground several times over the spring and summer, rewarding you with beautiful butterflies. This tender perennial, which tolerates some shade, recovers and resprouts quickly.
For an abundance of leaf material and a ready source of food for the pipevine swallowtail, the best choice is our native species, woolly Dutchman's pipe (A. tomentosa). This twining vine has huge leaves, sometimes reaching dinner-plate size, and can grow to heights of 25 feet or more. While not often found in the area nursery trade, Texas Discovery Gardens at Fair Park sells it and A. fimbriata at its semiannual plant sales; the next sale is Nov. 6 (www.Texas DiscoveryGardens.org).
When buying pipevines, read the plant label and memorize the proper botanical names to be sure you're purchasing one that not only will give you enjoyment in your garden but will not harm the local butterfly population.
Dale Clark runs a butterfly farm in Glenn Heights.