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Butterfly Gardening and Habitat Program

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Water Dropwort

(Oxypolis filiformis)

Other common names for this plant include Water Cowbane

The Black Swallowtail butterfly is widespread and ranges over most of the United States, with the exception of some western states. Caterpillars of this butterfly are commonly found munching away on the leaves and flowers of easily grown (nonnative) herbs such as parsley, dill, and fennel. While Black Swallowtails populations seem to be thriving even without the promotion of native caterpillar food plants, water dropwort is recommended for those butterfly gardeners who wish to try something different in their butterfly garden.

Water dropwort will grow well in damp or moist areas of the garden and complements wildflower meadows, habitat restorations, or naturalistic garden settings. Similar in form to the widespread (nonnative) Queen Anne's lace (Daucus carota), water dropwort is perennial and will spread by seed.

Importance as a caterpillar food source: Water dropwort is one of the few garden worthy native food plants for Black Swallowtail caterpillars.

Importance as a butterfly nectar source: A fair source of nectar that also attracts many other pollinators.

The current rating for Water Dropwort:

Nectar Rating
Caterpillar Rating

If you have experience growing water dropwort, we would like your opinion. Let us know how it performed in your butterfly garden. Your comments will help other butterfly gardeners in your region to create better butterfly gardens:


Water Dropwort Cultural Requirements
USDA Hardiness Zone
Bloom Period
Summer through fall
Bloom Color
Plant Height
2 to 3 feet or more
Plant Spread
Light Exposure
Full sun
Soil Moisture
Wet, even marshy
Animal/Disease Problems


Water Dropwort (Oxypolis filiformis)


Native range for Water Dropwort (Oxypolis filiformis






©2008 North American Butterfly Association