giant sumpweed

(Cyclachaena xanthiifolia)

Conservation Status
giant sumpweed
  IUCN Red List

not listed

     
  NatureServe

N5? - Secure

SNR - Unranked

     
  Minnesota

not listed

     
           
Wetland Indicator Status
     
  Great Plains

FAC - Facultative

     
  Midwest

FAC - Facultative

     
  Northcentral & Northeast

FAC - Facultative

     
           
 
Description
 
 

Giant sumpweed is a 18 to 72 tall, erect, annual forb that rises from a taproot.

The stems are erect or ascending, finely ridged or grooved, and grayish-green. They are usually unbranched but sometimes have straight, upright branches. They are hairless near the base and are sparsely to moderately covered with fine curved or curled curled hairs above the base.

The leaves are mostly opposite, though the uppermost are sometimes alternate. Lower leaves are long-stalked, the stalks up to 2¾ long or longer stalks. Upper leaves are short-stalked, the stalks up to long or longer. The leaf blades are egg-shaped, often very broadly egg-shaped, 2 to 4¾ long or longer, and 1 to 5 wide. They are angled or tapered at the base and tapered to a sharp point at the tip. The lower leaves are sometimes shallowly 3-lobed. There are 3 main veins. The upper surface is slightly rough with a sparse to moderate covering of straight, stiff, sharp, appressed hairs. The lower surface is paler and silky with a moderate to dense covering of long, soft, somewhat appressed hairs. The margins are coarsely toothed, often double toothed, with sharp, forward-pointing teeth.

The inflorescence is a branched array (panicle) with numerous small flower heads at the end of the stems and branches and also rising from the upper leaf axils.

The individual flower heads droop at the end of a 3 16 to ¼ long or longer stalk. The whorl of bracts at the base of the flower head (involucre) is 1 16 to long. The disk is composed of 8 to 20, usually no more than 10, male (staminate) florets in the center and usually 5 female (pistillate) florets around the margin.

The staminate florets have stamens with the filaments fused into a tube and the anthers free but closely arranged in a ring. The corolla is about 1 16 long and white to pale yellow.

The pistillate florets have stamens with the filaments into a tube and the anthers free but closely arranged in a ring. The corolla is sometimes absent. When present it is about 1 64 long and whitish.

The fruit is an egg-shaped, dark brown to nearly black, 1 16 to long achene with a tuft of hairs attached to one end.

 
     
 

Height

 
 

18 to 72

 
     
 

Flower Color

 
 

White to pale yellow

 
     
 

Similar Species

 
 

 

 
     
 
Habitat
 
 

Moist. Shores, disturbed sites.

 
     
 
Biology
 
 

Flowering

 
 

August to October

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

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

 
  8/22/2020      
         
 

Nativity

 
 

 

 
         
 

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 (flowering plants)  
  Superorder Asteranae  
 

Order

Asterales (sunflowers, bellflowers, fanflowers, and allies)  
 

Family

Asteraceae (sunflowers, daisies, asters, and allies)  
  Subfamily Asteroideae  
  Supertribe Helianthodae  
  Tribe Heliantheae (sunflowers and allies)  
  Genus Cyclachaena (giant sumpweed)  
       
 

This genus and five other genera were recently (2000) separated from the genus Iva. The new genus Cyclachaena contains only one species, Cyclachaena xanthiifolia. Many sources continue to use the former name, Iva xanthiifolia.

In 2009 the spelling of the species level name was “corrected” from xanthifolia to xanthiifolia.

 
       
 

Subordinate Taxa

 
 

 

 
       
 

Synonyms

 
 

Cyclachaena xanthifolia

Iva xanthifolia

Iva xanthiifolia

 
       
 

Common Names

 
 

big marsh-elder

bur-weed marsh-elder

burweed marshelder

carelessweed

false ragweed

giant marshelder

giant sump-weed

giant sumpweed

horseweed

marsh-elder

marshelder

rag sumpweed

 
       

 

 

 

 

 

 

 

 

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.

 

Corolla

A collective name for all of the petals of a flower.

 

Panicle

A pyramidal inflorescence with a main stem and branches. Flowers on the lower, longer branches mature earlier than those on the shorter, upper ones.

       
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Plant

  giant sumpweed   giant sumpweed
       
  giant sumpweed   giant sumpweed
       
  giant sumpweed    
       

Inflorescence

  giant sumpweed   giant sumpweed
       
  giant sumpweed    
       

Flower Heads

  giant sumpweed    
       

Leaves

  giant sumpweed    
       
       

 

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