The cheerfully bright-yellow golden alexanders is an easy-to-grow native host in our area for the black swallowtail caterpillar—though the caterpillar will also eat the non-native Queen Anne’s Lace, parsley, and other plants of the Apiaceae, or carrot (sometimes called parsley), family. The plant has a wide range and can be found in the wild throughout the eastern United States, into Canada, and west to the Rocky Mountains.
Blooming midspring through June, golden alexanders grows in a range of soils, including clay and sand. It can take partial shade to full sun. While it likes wet soil, it will tolerate drying out, which makes it a good rain-garden plant.
Golden alexanders can get a little exuberant when it comes to reseeding, so, in small gardens where plant diversity is desired, plant it where there’s some shade, which dampens its enthusiasm a bit. For a more traditional look, cut off the spent flowers as their blooms fade. This keeps the plants tidy and also keeps reseeding to a minimum, preventing the creation of a little colony; though some gardeners revel in its tendency to fill space by spreading through seed. The pretty, spikey foliage and happy 3-inch yellow umbels make these plants worth the trouble—and what could be better than playing host to black swallowtail babies, some of whom will serve as food for breeding birds?
Golden alexanders: Zizia aurea
Black swallowtail: Papilio polyxenes
Black swallowtail caterpillar image used with permission from the North Carolina Botanical Gardens blog, at http://aroundthegarden.tumblr.com/
Black swallowtail adult visiting golden alexanders used with permission from Janet Allen, whose blog can be found at www.ourhabitatgarden.org