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Canadian Clearweed (Pilea pumila (L.) A. Gray)

Also known as Canadian clear weed, coolwort, richweed, dwarf clearweed.

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Summary
Range
Similar Plants
Habitat
Life Cycle
Notes
Links
Photos

Photo © Tom Scavo, CC BY 4.0.

↑Summary

An annual with transluscent stems and foliage found in a wide variety of lightly-shaded wet areas.

↑Range - Expand

Legend	Color
Native
Native or Not Present

This tentative map is based on our own research. It may have limited data on Canada and/or Mexico, and there is some subjectivity in our assignment of plants as introduced vs. expanded. Read more in this blog post.

↑Similar Plants

Black-fruited Clearweed (Pilea fontana)
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↑Habitat

Grows in moist to wet areas in light shade, and rich, loamy soil. Usually requires some exposure of soil to germinate. Established plants are able to survive temporary flooding, but not standing water.

Mostly found in forests, especially floodplain forests but also poorly drained sites in upland forests.

Also thrives in wet, poorly-drained areas of shady yards and gardens.

↑Life Cycle

This species is a strict summer annual. Seeds sprout in spring, where they often blanket areas of exposed soil. Only a small portion of these plants will reach maturity.

Flowers are inconspicuous and wind-pollinated. The plant dies after producing seeds. Usually found in large patches or colonies where conditions favor it.

Populations ebb and flow with changing weather patterns from year to year, affected by moisture levels.

↑Notes

This species is initially hindered by the allelopathy of garlic mustard (Alliaria petiolata), which commonly occurs in the same habitats, but it is able to adapt to the presence of garlic mustard after several generations.

Among common names, we recommend avoiding the use of the term "dwarf clearweed" becaause this is not necessarily the smaller of the two Pilea or clearweed species in much of its range, and this name can lead to confusion with the other species, black-fruited clearweed (Pilea fontana), which is often misleadingly referred to as "lesser clearweed". The sizes of the two species almost completely overlap and are not useful for distinguishing them.