American willowherb

(Epilobium ciliatum ssp. ciliatum)

Conservation Status
American willowherb
  IUCN Red List

not listed

     
  NatureServe

N5 - Secure

SNR - Unranked

     
  Minnesota

not listed

     
           
Wetland Indicator Status
     
  Great Plains

FACW - Facultative wetland

     
  Midwest

FACW - Facultative wetland

     
  Northcentral & Northeast

FACW - Facultative wetland

     
           
 
Description
 
 

American willowherb is a 2 to 48 tall, erect, perennial forb that rises on usually a single stem from a compact, persistent rosette of basal leaves. It does not produce long, horizontal, underground stems (rhizomes) or underground winter buds (turions).

The stem is erect and usually has many branches, near the base as well as near the top. It is often tinged with red. It has raised lines of fine, short hairs extending downward from the margins of the leaf stalks, at least near the top.

Stem leaves are alternate but are so close together that they appear opposite near the bottom of the stem and often opposite or nearly opposite near the top. Lower leaves are on 1 32 to long leaf stalks, upper leaves are stalkless. The leaf blades are narrowly lance-shaped to narrowly egg-shaped, 1¼ to 4¾ long, and ¼ to 1 wide. They are rounded at the base and taper to a point at the tip with straight or slightly concave sides along the tip. The veins are conspicuous and are deeply sunken on the upper surface. The upper and lower surfaces are almost hairless except for straight, stiff, sharp, appressed hairs along the veins. The margins are toothed with 2 to 5 shallow, sharp, forward pointing teeth per of margin.

The inflorescence is an erect, open, branched cluster of many flowers at the end of the stem and branches.

The flowers are to ½ wide. There are 4 white to light purple or pink petals. The petals are deeply notched at the tip, sometimes appearing as 4 pairs of petals. The stigma is not branched.

The fruit is a long, hairy capsule containing numerous seeds. The capsule is 1½ to 4 long and is held erect on a 1 16 to long stalk.

 
     
 

Height

 
 

2 to 48

 
     
 

Flower Color

 
 

White to light purple or pink

 
     
 

Similar Species

 
 

Downy willow herb (Epilobium strictum) stem is unbranched or has just a few branches. Middle and upper stem leaves are evidently alternate. The leaves are narrower, no more than 5 16 wide. The upper leaf surface is densely covered with straight, spreading or ascending hairs. The leaf margins are untoothed and are rolled backward (toward the underside).

Narrow-leaved willow herb (Epilobium leptophyllum) has narrower leaves, no more than ¼ wide. The leaf margins are untoothed and are rolled backward (toward the underside). The upper leaf surface is covered with straight, stiff, sharp, appressed hairs across the entire surface.

Northern willow herb (Epilobium ciliatum ssp. glandulosum) rises from a large, fleshy, underground turion. It is usually unbranched or only sparsely branched near the top. The leaves are wider and egg-shaped or narrowly egg-shaped. The inflorescence is narrow, dense, leafy, and mostly unbranched. The flowers are larger, up to long, and darker, pink to rose-purple, rarely white.

Purple-leaf willow herb (Epilobium coloratum) stems and leaves are often tinted purple. The leaves are often blotched with purple. The leaf margins are more densely toothed, with 4 to 8 teeth per of margin. The fruit is smaller, no more than 2 long.

 
     
 
Habitat
 
 

Wet. Streambanks, roadsides, disturbed places.

 
     
 
Biology
 
 

Flowering

 
 

June to August

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

3, 7, 4, 5, 7, 28.

 
  1/6/2014      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

 

 
         
 
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 Myrtales (myrtles, evening primroses, and allies)  
 

Family

Onagraceae (evening primrose)  
  Subfamily Onagroideae  
  Tribe Epilobieae  
 

Genus

Epilobium (willowherb)  
  Section Epilobium  
  Species Epilobium ciliatum (fringed willowherb)  
       
 

Subordinate Taxa

 
 

 

 
       
 

Synonyms

 
 

Epilobium adenocaulon

Epilobium adenocaulon var. ecomosum

Epilobium adenocaulon var. holosericeum

Epilobium adenocaulon var. parishii

Epilobium adenocaulon var. perplexans

Epilobium americanum

Epilobium brevistylum

Epilobium brevistylum var. ursinum

Epilobium californicum

Epilobium californicum var. holosericeum

Epilobium ciliatum var. ecomosum

Epilobium delicatum

Epilobium ecomosum

Epilobium glandulosum var. adenocaulon

Epilobium glandulosum var. ecomosum

Epilobium glandulosum var. macounii

Epilobium leptocarpum var. macounii

Epilobium ursinum Parish

Epilobium watsonii var. parishii

 
       
 

Common Names

 
 

American willowherb

ciliated willow-herb

coast willowweed

fringed willowherb

hairy willow-herb

northern willowherb

 
       

 

 

 

 

 

 

 

 

Glossary

Rhizome

A horizontal, usually underground stem. It serves as a reproductive structure, producing roots below and shoots above at the nodes.

 

Turion

A usually fleshy bud that overwinters and from which new growth emerges in the spring; winter bud.

       
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  American willowherb   American willowherb
       
       

 

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