common ragweed

common ragweed

 

 

 

 

 

 

 

 

 

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Ambrosia artemisiifolia


Nativity

Native

Status

 

Habitat

Disturbed sites

Flowering

August to September

Flower Color

Green

Height

12 to 40


Identification

This is a 12 to 40, usually 12 to 24 tall, erect, annual forb that rises from a taproot.

The stems are erect, bushy, frequently branched at least above the middle, and hairy.

Leaves are opposite near the base, alternate above. They are deeply cut into lobes that are spaced out along the midrib but not cut to the midrib. The lobes are themselves deeply cut into lobes that are spaced out along the midrib but not cut to the midrib (the lobes are pinnatifid, the leaves are bipinnatifid). The leaves are 1 to 3½ long, usually no longer than 2, and ¾ to 2 wide, usually no wider than 1. They are wider at the base than at the tip. The upper and lower surfaces are gland-dotted and, on younger leaves, covered with stiff hairs that are either straight or appressed. Mature leaves are relatively hairless. The leaves are on stalks that can be 1 to 2 long, but are usually no more than 1 long.

There are separate male and female flowers, both borne on the same plant. Male flowers are borne in spike-like inflorescences at the ends of stems and branches. The spikes are up to 4 long with 12 to 20 or more flower heads. The heads are green, bead-like, and about in diameter. They hang downward at the end of short stalks. Female flowers appear singly from upper leaf axles. Both flowers are rayless.

The fruit is an achene without tufts of hair.

 
Similar
Species

Annual bursage (Ambrosia acanthicarpa) also has bipinnately lobed leaves and closely resembles common ragweed. However, its leaves are covered with white to gray, short, bristly hairs.

Giant ragweed (Ambrosia trifida var. trifida) is a much taller plant. Its leaves are palmately lobed.

Lance-leaved ragweed (Ambrosia bidenta) leaves, as the latin name suggests, have two teeth, one on each side of the leaf.

Western ragweed (Ambrosia psilostachya) leaves are pinnatifid (once cut), not bipinnatifid (twice cut).


Range Range Map   Sources: 2, 3, 4, 5, 7, 22, 28.
 
Sightings

Afton State Park

Agassiz Dunes SNA

Banning State Park

Big Stone Lake State Park

Blanket Flower Prairie SNA

Blue Devil Valley SNA

Blue Mounds State Park

Bonanza Prairie SNA

Buffalo River State Park

Bunker Hills Regional Park

Butternut Valley Prairie SNA

Camden State Park

Carver Park Reserve

Cedar Rock SNA

Chamberlain Woods SNA

Charles A. Lindbergh State Park

Cherry Grove Blind Valley SNA

Chimney Rock SNA

Chippewa Prairie

Clear Lake SNA

Clinton Prairie SNA

Compass Prairie SNA

Cottonwood River Prairie SNA

Crow Wing State Park

Crow-Hassan Park Reserve

Des Moines River SNA

Dodge Nature Center

Elm Creek Park Reserve

Falls Creek SNA

Felton Prairie SNA
Bicentennial Unit
Shrike Unit

Flandrau State Park

Fort Ridgely State Park

Franconia Bluffs SNA

Frenchman’s Bluff SNA

Glynn Prairie SNA

Gneiss Outcrops SNA

Great River Bluffs State Park

Greenleaf Lake SRA

Grey Cloud Dunes SNA

Hardscrabble Woods / MG Tusler
Sanctuary

Hastings Sand Coulee SNA

Hastings SNA

Holthe Prairie SNA

Hythecker Prairie SNA

Joseph A. Tauer Prairie SNA

Kasota Prairie SNA

Kellogg-Weaver Dunes SNA
Kellogg-Weaver Unit

Kilen Woods State Park

King's and Queen's Bluff SNA

Lake Bemidji State Park

Lake Elmo Park Reserve

Lake Rebecca Park Reserve

Lost Valley Prairie SNA

Lundblad Prairie SNA

Maplewood State Park

Mary Schmidt Crawford Woods SNA

McKnight Prairie

Minneopa State Park

Minnesota Valley NWR
Louisville Swamp Unit

Minnesota Valley State Recreation Area
Lawrence Unit

Monson Lake State Park

Morton Outcrops SNA

Mound Prairie SNA

Mound Spring Prairie SNA

Myre-Big Island State Park

Old Mill State Park

Ordway Prairie

Oronoco Prairie SNA

Osmundson Prairie SNA

Ottertail Prairie SNA

Pankratz Memorial Prairie
North Unit

Pembina Trail Preserve SNA
Crookston Prairie Unit

Pine Bend Bluffs SNA

Plover Prairie
East Unit

Prairie Coteau SNA

Prairie Smoke Dunes SNA

Racine Prairie SNA

Regal Meadow

Rice Lake Savanna SNA

Rice Lake State Park

Richard M. & Mathilde Rice Elliott SNA

Ripley Esker SNA

River Terrace Prairie SNA

Rock Ridge Prairie SNA

Roscoe Prairie SNA

Rushford Sand Barrens SNA

St. Croix Savanna SNA

Schaefer Prairie

Sedan Brook Prairie SNA

Seminary Fen SNA

Seven Sisters Prairie

Sheepberry Fen

Split Rock Creek State Park

Spring Creek Prairie SNA

Spring Lake Park Reserve

Spring Prairie Preserve

Town Hall Prairie

Twin Lakes SNA

Twin Valley Prairie SNA

Uncas Dunes SNA

Upper Sioux Agency State Park

Western Prairie SNA

Wild Indigo Prairie SNA

Wild River State Park

William O’Brien State Park

Yellow Bank Hills SNA


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Taxonomy

Family:

Asteraceae (aster)

 

Subfamily:

Asteroideae

 

Supertribe:

Helianthodae

 

Tribe:

Heliantheae (sunflower)

 

Subtribe:

Ambrosiinae

 
Synonyms

Ambrosia artemisiifolia var. artemisiifolia

Ambrosia artemisiifolia var. elatior

Ambrosia artemisiifolia var. paniculata

Ambrosia elatior

Ambrosia glandulosa

Ambrosia maritima

Ambrosia monophylla

Ambrosia paniculata

 
Common
Names

annual ragweed

common ragweed

ragweed


 

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.

 

allelopathy

The release of a chemical toxin by one plant to inhibit the growth or germination of nearby competing plants.

 

axil

The upper angle where the leaf stalk meets the stem.

 

bipinnatifid

Twice pinnatifid.

 

palmately Lobed

Similar to a hand. Having more than three lobes that radiate from a single point at the base of the leaf.

 

pinnatifid

Deeply cut into lobes that are spaced out along the midrib but not cut to the midrib; the lobes do not form separate leaflets.

 

rhizome

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

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