Canadian clearweed

(Pilea pumila)

               
Conservation Status

IUCN Red List

not yet assessed

 

No image available

NatureServe

N5 - Secure

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

FAC - Facultative

Midwest

FACW - Facultative wetland

Northcentral & Northeast

FACW - Facultative wetland

Nativity

Native

Occurrence

Common

Habitat

Moist to wet. Woodlands, woodland margins, and streambanks. Full shade. In rich soil.

Flowering

July to September

     
Flower Color

Greenish-white

     
Height

4 to 20

     

Identification

This is a 4 to 20 tall, erect, annual forb that rises on a single stem from fibrous, shallow, adventitious roots. It often forms large colonies.

The stems are erect, light green grayish-green, or reddish-green, transparent, unbranched, smooth, and hairless. The are round in cross section.

The leaves are opposite, thin, elliptic to broadly elliptic or egg-shaped, 1¼ to 5 long, and to 3½ wide. They are on leaf stalks that are often 1 long or longer. Each leaf is equal in size to the leaf on the opposite side of the stem. The leaf blade is broadly wedge-shaped or rounded at the base. It does not have ear-like lobes at the base. It is slightly transparent, most noticeably on the lower surface. The margins are coarsely toothed with sharp or rounded, forward-pointing teeth. The tooth at the tip is elongated. The upper surface is medium to dark green, shiny, and hairless. The lower surface is light green and hairless. There are three parallel main veins, the midvein and two lateral veins that arch toward the tip. The veins are conspicuously depressed on the upper surface, giving the leaf blade a quilted or wrinkled appearance. The leaves turn bright yellow in the fall.

The inflorescence is a crowded or loose, ¼ to 1¼ long, branched, flat-topped cluster (cyme) rising from the upper leaf axils. The cyme is 55% to 70% as long as wide and shorter than the leaf stalk. It contains both male and female flowers.

The flowers are less than long and about 1 32 in diameter. Male flowers have no petals, 4 greenish-white sepals, and 4 stamens. Female flowers have no petals, 3 greenish-white sepals, and 1 style. The flowers are not fragrant.

The fruit is a dry, tear-drop shaped, 1 32 to 6 16 long seed case (achene). It is green or greenish-yellow at maturity, sometimes with fine, purple lines. The purple lines, when present, are sometimes slightly raised.

 
Similar
Species

Stinging nettle (Urtica dioica ssp. gracilis) is a much taller plant, up to 72 in height. The stem and leaves have stinging hairs.


Distribution Distribution Map  

Sources: 2, 3, 4, 5, 7, 28.


Comments

 


Taxonomy

Family:

Urticaceae (nettle)

 
Synonyms

Adicea pumila

Urtica pumila

Pilea pumila var. deamii

Pilea pumila var. pumila

 
Common
Names

Canada clearweed

Canadian clearweed

clearweed


 

 

 

 

 

 

 

 

 

Glossary

achene

A dry, one-chambered, single-seeded fruit, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed entirely from the wall of the superior ovary, does not split open at maturity, but relies on decay or predation to release the contents.

 

adventitious roots

Roots originating on any part of the plant other than the usual underground root zone: the lower stem above ground, the branches, or the leaves.

 

axil

The upper angle where the leaf stalk meets the stem.

 

cyme

A branched, flat-topped or convex flower cluster in which the terminal flower opens first and the outermost flowers open last.

 

sepal

An outer floral leaf, usually green but sometimes colored, at the base of a flower.

       

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  Identifying and Removing Clearweed
Growing Wisdom
 
   
 
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Uploaded on Jan 14, 2010

Dave shows you how to identify and remove clearweed.

 
     

 

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