How to Identify Common Milkweed

Common milkweed, Asclepias syriaca, grows wild in fields, meadows and along roadsides in the East, Northeast and Midwest portions of the United States. Gardeners plant milkweed to attract butterflies. The host plant for the monarch butterfly, milkweed's nectar is a source for many butterfly species, hummingbirds and hummingbird clearwing moths. Follow these steps to learn to identify the common milkweed.

Difficulty: Moderate

Instructions

1. Note the plant's height. Common milkweed grows from 2 to 6 feet high and typically has a single, fairly thick stem.

2. Inspect the leaves. They grow opposite one another along the stem. Oval shaped and narrow, they are from 2 to 10 inches long, smooth on top and hairy underneath.

3. Break open or cut the stem. The plant's stem oozes a thick, white sap, which looks like milk.

4. Check for flowering in late June to August. Milkweed flowers grow in little clusters, ranging in colors from pink to lavender.

5. Look for seedpods in the fall when flowers change into pods. With a warty outer skin, pods are full of white fluff that carries seeds with the wind.

Tips & Warnings

• Milkweed is the only plant the monarch butterfly and larvae eat. They lay their eggs on stems and leaves, and the growing caterpillars eat the leaves.
• Milkweed leaves contain toxins, which are not harmful to monarchs, but make monarch caterpillars and butterflies poisonous to most predators.

Resources

• Go to Science Views for photos of common milkweed.