How much sun does Water cowbane need?

Water cowbane grows best in full sun conditions.

When does Water cowbane bloom?

Water cowbane blooms in August, September, and October.

Where is Water cowbane native?

Water cowbane (Oxypolis filiformis) is native to AL, FL, GA, LA and 4 more states, per the World Checklist of Vascular Plants (Kew).

What butterflies or moths does Water cowbane host?

Water cowbane is a larval host plant for eastern black swallowtail.

Water cowbane

Name: Pollinator Patch
Author: Pollinator Patch

Oxypolis filiformis

Last reviewed: October 2026

Water cowbane (Oxypolis filiformis) is a perennial forb native to AL, FL, GA, LA and 4 more states. It blooms in August, September, and October. The flowers draw bees, wasps, and flies.

Toxicity unknown

Water cowbane (Oxypolis filiformis) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

Light

full sun

Water

high

Size

24"–60" H × 12"–18" W

Bloom

Aug, Sep, Oct

Native to

AL, FL, GA, LA and 4 more states

Pollinators

bees, wasps, flies

Before you buy

Your city may pay you to plant this

Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 458 programs across 44 states, each with a link to the provider and the date we last checked it.

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Browse plants for this ecoregion

Middle Atlantic Coastal Plain Southeastern Plains Southern Coastal Plain Southern Florida Coastal Plain

Tall, slender perennial with thread-like compound leaves and flat-topped clusters of small white flowers in late summer. Found in wet pine savannas and bog margins.

Growing Water cowbane

Grow Water cowbane in full sun and high water. Mature plants reach 24 to 60 inches tall and spread 12 to 18 inches wide.

Wildlife value

Host plant for eastern black swallowtail.

Larval host plant for the eastern black swallowtail butterfly; flowers attract a wide range of bees, wasps, and flies.

Common questions

How much sun does Water cowbane need?: Water cowbane grows best in full sun conditions.
When does Water cowbane bloom?: Water cowbane blooms in August, September, and October.
Where is Water cowbane native?: Water cowbane (Oxypolis filiformis) is native to AL, FL, GA, LA and 4 more states, per the World Checklist of Vascular Plants (Kew).
What butterflies or moths does Water cowbane host?: Water cowbane is a larval host plant for eastern black swallowtail.

Native range data from the World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

If something looks wrong

Common plant problems, and what to check first

These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.

See all plant problem guides

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