Pilea pumila, known as clearweed, Canadian clearweed, coolwort, or richweed is an annual plant native to most of North America east of the Rockies. The plants are generally erect, 10 to 70 cm tall, often occurring in large colonies, and are quite common throughout their range both as a woodland plant and a weed of gardens.
The foliage is opposite, simple with dentate margins, wrinkly (with depressed veins), ovate, and with long petioles. Both the leaves and stems are translucent and bright green, turning bright yellow in autumn. The flowers are small, borne in axillary cymes, unisexual with both genders occurring on the same plant, greenish yellow, and pollinated by wind. Flowers bloom from midsummer through early autumn. Fruits (achenes) are green with purple markings. Roots are fibrous, shallow, and adventitious off the stem in moist areas or when in contact with the soil.
This plant is most often found in rich, moist soils in both sunny and shaded locations. It is sometimes grown as a ground cover or for attracting deer.
- P. D. Strausbaugh and Earl L. Core. Flora of West Virginia. 2nd ed. Seneca Books Inc., 1964. ISBN 0-89092-010-9, page 318
- Ann Fouler Rhoads and Timothy A. Block. The Plants of Pennsylvania. University of Pennsylvania Press, 2000. ISBN 0-8122-3535-5, page 694
- Hortus Third, page 873
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