white prairie aster

(Symphyotrichum falcatum var. commutatum)

               
Conservation Status

IUCN Red List

not listed

white prairie aster (var. commutatum)

NatureServe

N4N5 - Apparently Secure to Secure

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

FACU - Facultative upland

Midwest

FAC - Facultative

Northcentral & Northeast

FAC - Facultative

Nativity

Native

Occurrence

 

Habitat

Dry to moderate moisture. Prairies, meadows. Full sun.

Flowering

August to October

     
Flower Color

White ray florets, yellow disk florets

     
Height

4 to 24

     
 
Identification

This is an erect, perennial forb. It usually rises a single stem from a long rhizome. Sometimes it rises on 2 to 5 or more clumped stems from a group of short, entangled rhizomes. New shoots develop at the end of elongated rhizomes. A mature plant can be from 4 to 31 tall, though in Minnesota it is usually no more than 24 in height. It is usually found in colonies.

The stem is ascending to erect, grayish-brown to brown, and usually branched above the middle. It is usually densely covered with short, upward-curved hairs. The stem is green when young, becoming grayish-brown to brown when the plant matures.

Basal leaves are to 1½ long, to wide, inversely lance-shaped, firm, and stalkless. They are tapered at the base and rounded or angled at the tip with an abrupt, short, sharp, hard point at the tip. The upper and lower surfaces are rough to the touch and usually sparsely to moderately covered with straight, stiff, sharp, appressed hairs. The margins are usually untoothed and have a fringe of spreading or forward-pointing hairs. By the time the plant is in flower the basal leaves have withered.

Lower stem leaves similar to basal, alternate, inversely lance-shaped to oblong, to 1½ long or longer, 1 16 to wide or wider, becoming progressively smaller as they ascend the stem. They are wedge-shaped at the base, rough to the touch, and are sparsely to densely covered with straight, stiff, sharp, appressed hairs.

Upper stem leaves similar to lower, linear oblong to linear lance-shaped, 1 to 1¾ long, and 1 16 to wide. Leaves on the branches are evenly distributed around the branch, notarranged on one side of the branch.

The inflorescence is an elongated, branched cluster (panicle) of usually 10 to 200 or more flower heads at the end of the stem and branches. The panicles have short to long, ascending branches with 1 or a cluster of 2 to 10 or more uncrowded flower heads per branch. The flower heads are usually clustered at the end of the panicle branch, and are not arranged on one side of the branch. The flower heads and clusters are on stout, up to 2 long stalks (peduncles). The stalks have 2 to 10 or more somewhat leaf-like bracts. The bracts are to 5 16 long, linear to lance-shaped, and densely hairy.

The flower heads are to ¾ in diameter. The whorl of smaller bracts subtending the flower head (involucre) is bell-shaped. The bracts of the involucre are linear lance-shaped to oblong inversely lance-shaped, thickened toward the base, abruptly bent backward, and tapered at the tip with a short, sharp, spine-like point at the tip. The margins of the bracts have a dense fringe of spreading hairs.

The flower heads have 15 to 35 (usually at least 20) ray florets and 8 to 30 (usually at least 18) yellow disk florets. The ray florets are usually white, rarely pink or blue. The disk florets become brown with age.

The fruit is an achene with a tuft of whitish hairs at the tip.

 
Similar
Species

White prairie aster (Symphyotrichum falcatum var. falcatum) rises in tufts of 1 to 5 or more stems from a short, solid, woody, underground stem. New shoots develop near the bases of old stems. The stems are sparsely covered with straight, stiff, sharp, appressed hairs. The peduncles are long and slender and have no more than 5 bracts.

 
Distribution Distribution Map   Sources: 4, 5, 7.
 
Comments

 

 
Taxonomy

Family:

Asteraceae (aster)

 

Subfamily:

Asteroideae

 

Supertribe:

Asterodae

 

Tribe:

Astereae (aster)

 

No Rank:

North American clade

 
Parent

white prairie aster (Symphyotrichum falcatum)

 
Synonyms

Aster commutatus

Aster commutatus var. polycephalus

Aster cordineri

Aster ericoides var. commutatus

Aster falcatus ssp. commutatus

Aster falcatus var. commutatus

Aster multiflorus var. commutatus

Aster nahanniensis

Aster polycephalus

 
Common
Names

white prairie aster

 

 

 

 

 

 

 

 

 

 

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.

 

Bract

Modified leaf at the base of a flower stalk or flower cluster.

 

Involucre

A whorl of bracts beneath or surrounding a flower or flower cluster.

 

Linear

Long, straight, and narrow, with more or less parallel sides, like a blade of grass.

 

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.

 

Peduncle

The stalk of a single flower or flower cluster.

 

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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Plant

  white prairie aster (var. commutatum)   white prairie aster (var. commutatum)
       
  white prairie aster (var. commutatum)    
       

Inflorescence

  white prairie aster (var. commutatum)   white prairie aster (var. commutatum)
       
       

 

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