Canadian clearweed

(Pilea pumila)

Conservation Status

 

No image available

 
  IUCN Red List

not listed

     
  NatureServe

N5 - Secure

SNR - Unranked

     
  Minnesota

not listed

     
           
Wetland Indicator Status
     
  Great Plains

FAC - Facultative

     
  Midwest

FACW - Facultative wetland

     
  Northcentral & Northeast

FACW - Facultative wetland

     
           
 
Description
 
 

Canadian clearweed 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.

 
     
 

Height

 
 

4 to 20

 
     
 

Flower Color

 
 

Greenish-white

 
     
 

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.  
     
 
Habitat
 
 

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

 
     
 
Biology
 
 

Flowering

 
 

July to September

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

2, 3, 4, 5, 7, 28, 30.

 
  3/30/2021      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

Common

 
         
 
Taxonomy
 
  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (dicots)  
  Subclass Rosidae  
  Superorder Rosanae  
 

Order

Rosales (roses, elms, figs, and allies)  
 

Family

Urticaceae (nettle)  
 

Genus

Pilea (clearweed)  
       
 

Subordinate Taxa

 
 

 

 
       
 

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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Other Videos
 
  Identifying and Removing Clearweed
Growing Wisdom
 
   
 
About

Uploaded on Jan 14, 2010

Dave shows you how to identify and remove clearweed.

   
       

 

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