Carrot Family Hostplants

Like most families, the Carrot/ Parsley family contains both saints and sinners. The cook harvests many delicious human foods such as Carrots, Dill, Parsley, Parsnips and Celery. And many of us became butterfly gardeners after discovering “stinky worms” in our herb gardens. However, these caterpillars of the Eastern Black Swallowtails (aka EBS) don’t eat Cilantro, whose soapy aroma repels many insect pests including mosquitoes. Socrates could have told you that the family contains dangerously poisonous plants to humans and livestock. EBS caterpillars do feast on Poison Hemlock, but that deadly Carrot family member would NOT be welcome in my garden.

My Recommendation: Fennel

Fortunately, there is an outstanding family member that meets the needs of both EBS caterpillars and gardeners: Common Fennel and its more glamorous variety, ‘Smoky’. Full sun and well-draining soil produce vigorous ferny perennial plants soaring up to 6 feet tall with the delicious smell and taste of licorice. (I nibble the flower buds as I garden.) The Common has soft blue-green foliage and pale-yellow flowers, while ‘Smoky’ has striking bronze foliage and sulfur-yellow flowers. Like many Carrot family crops, Fennel should be directlysown outdoors in spring rather than transplanted. Gardeners appreciate that the resulting taproot bequeaths the gift of drought-tolerance.

In spring, established plants quickly form blue-green or bronze mounds that begin to bloom in late June. To control rampant selfseeding, I chop the towering stalks down to 2 inches tall in late July, but only after inspection and relocation of any EBS caterpillars. The plants quickly grow back to 2-foot mounds, perfect for the fall batch of EBS caterpillars that will overwinter in their chrysalids. Despite my draconian dead-heading, spring always brings a few new seedlings, which I immediately remove before their taproots head for China.

Risky Native Selections

An inhabitant of sunny prairie seeps, Golden Alexanders is the commonly recommended native choice. I enthusiastically endorse its beauty; however, I’ve only seen caterpillars feeding twice in 20 years. In my garden, the EBS prefer Fennel. Prairie Parsley and Prairie Parsnip serve as full sun biennial hostplants, but look weedy to my eye. Many other native Carrot Family members are not hostplants and lack redeeming virtues. For instance, Hedge Parsley, which looks like a diminutive Queen Anne’s Lace, also has seeds that stick to your trousers and pets’ fur. Considering the many poisonous family look-alikes, selecting native hostplants can be risky for nonbotanists. But this time humans are heroes, having greatly increased Black Swallowtail populations by planting pesticide-free herb gardens.

New Carrot Hostplant Choices

Two relatively new introductions can expand your repertoire of beautiful Carrot Family members that will benefit both your gardening aesthetic and EBS moms looking to lay their heavy burden of eggs. The biennial Moon Carrot, Seseli gumniferum, hails from Turkey and grows in full sun and well-drained soil. It does self-seed, but not excessively to become a pest. The showy white flowers are borne in massive umbels from the evergreen blue foliage that makes this plant a four-season beauty. In my garden, it surpasses Fennel as the EBS caterpillars’ favorite hostplant.

The non-native Queen Anne’s Lace is relished by EBS caterpillars but has been declared invasive by 35 states. However, Queen Anne’s Lace ‘Dara’ moves past the ordinary white flower with shades of pale pink to maroon, depending on the plant. Unlike the species, Dara is not invasive and a border or meadow of these unusual blooms will shimmer for 2 months while the long-stemmed flowers last over a week in a bouquet. Both plants are sold at our Paola Plant Sale in April or can be purchased on the Internet. EBS caterpillars will thank you for venturing beyond the ordinary!

LENORA LARSON Butterfly Maven