giant sumpweed

(Cyclachaena xanthiifolia)

               
Conservation Status

IUCN Red List

not yet assessed

giant sumpweed

NatureServe

N5? - Secure

SNR - Unranked

Minnesota

None
Wetland
Indicator
Status

Great Plains

FAC - Facultative

Midwest

FAC - Facultative

Northcentral & Northeast

FAC - Facultative

Nativity

Native

Occurrence

 

Habitat

Moist. Shores, disturbed sites.

Flowering

August to October

     
Flower Color

White to pale yellow

     
Height

18 to 72

     

Identification

This 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.

 
Similar
Species

 


Distribution Range Map   Sources: 2, 3, 4, 5, 7, 28.

Comments

Taxonomy
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.

Common Misspelling
In 2009 the spelling of the species level name was “corrected” from xanthifolia to xanthiifolia. Most online authorities have been updated with the new spelling. The usually reliable ITIS37 has not.


Taxonomy

Family:

Asteraceae (aster)

 

Subfamily:

Asteroideae

 

Supertribe:

Helianthodae

 

Tribe:

Heliantheae (sunflower)

 
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
       

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  giant sumpweed   giant sumpweed
       

Flower Heads

  giant sumpweed    
       

Leaves

  giant sumpweed    
       
       
     

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MinnesotaSeasons.com Sightings

   

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Glacial Lakes State Park

 

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Spring Prairie Preserve

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