Canada clearweed (TVA, White's Creek Small Wild Area, Plants)

Canada clearweed

Pilea pumila

Summary ⁵

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.

Comments ⁶

The most unusual characteristic of this plant is the translucency of the foliage – this has been useful in biology classes to show the uptake of liquids from the roots into the stems and leaves. A less common species of Clearweed, Pilea fontana, has stems that are less translucent and its achenes are black, rather than green. Clearweed resembles other members of the Nettle family as well, but it lacks the stinging hairs that can be found on Urtica dioica (Stinging Nettle) and Laportea canadensis (Wood Nettle). While Boehmeria cylindrica (False Nettle) lacks stinging hairs, its stems aren't translucent and its racemes of flowers are more erect and longer than Clearweed's racemes.

Comments ⁷

Populations of this species from E Asia were described as Pileamongolica. The authors have examined material of this species, including plants from Asia and North America, and found the specimens were consistently characterized by the scorpioid cyme, 2(–4)-merous male flowers, and triangular-ovoid achene. There is no reason to separate populations from E Asia as a separate species. However, three varieties are recognized here.

The plants are used medicinally as a diuretic.

Comments ⁸

Typical plants have leaf blades with cuneate bases and 3-11 rounded teeth on each margin; plants with rounded leaf bases and 11-17 less rounded or acute teeth on each margin have been called Pilea pumila var. deamii (Lunell) Fernald (M. L. Fernald 1936) [ Adicea deamii Lunell, Amer. Midl. Naturalist 3: 10. 1913.]. Typical P . pumila also is found in eastern Asia, where three infraspecific taxa, P . pumila var. pumila , P . pumila var. hamaoi (Makino) C. J. Chen, and P . pumila var. obtusifolia C. J. Chen are recognized. This complex, which also includes P . pauciflora C. J. Chen, has been placed in Pilea series Pumilae C. J. Chen. Although the Asian plants are often vegetatively and florally indistinguishable from the North American plants, minor differences do occur in the achenes, especially in their markings and sculpturing when mature. Detailed studies are needed to clarify exact relationships.

Native Americans used Pilea pumila medicinally to alleviate itching, to cure sinus problems, and to treat excessive hunger (D. E. Moerman 1986)

Sources and Credits

(c) Tom Potterfield, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/tgpotterfield/12163077104/
(c) Gerrit Davidse, some rights reserved (CC BY-NC-SA), http://images.mobot.org/tropicosthumbnails/TropicosImages2/100170000/100170567.jpg
(c) Ronald Kielb, some rights reserved (CC BY-NC), https://www.flickr.com/photos/53874483@N03/5040357117/
(c) Charlie Hohn, some rights reserved (CC BY), uploaded by Charlie Hohn
Adapted by Jonathan (JC) Carpenter from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Pilea_pumila
(c) John Hilty, some rights reserved (CC BY-NC), http://eol.org/data_objects/29445534
(c) Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/19824340
(c) Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/19824338

More Info

iNat Map

‹ › ×