sawtooth sunflower

(Helianthus grosseserratus)

Conservation Status
sawtooth sunflower
  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
 
 

Sawtooth sunflower is an erect perennial forb that rises on a single stem from a short creeping rhizome or sometimes a longer, thick, branched rhizome. It often forms dense colonies. It can be up to 120 tall when appearing as a single plant, 24 to 60 tall when in a colony.

The stems are erect, stout, round, and green, becoming purple in strong sun. They are sometimes covered with a whitish, waxy bloom (glaucous). They are hairless and usually unbranched below the inflorescence. Within the inflorescence the stems are sparsely to moderately covered with short, appressed, upward pointing hairs.

There are usually 20 to 25 stem leaves. There are no basal leaves. Lower and middle stem leaves are usually alternate, sometimes opposite. Those near the top are always alternate. Lower stem leaves are narrowly lance-shaped to narrowly egg-shaped, 4 to 12½ long and 1½ to 3½ wide, 5 to 10 times as long as wide. They are often folded along the midrib, especially during hot and dry weather. They are on ¾ to 2 long leaf stalks. They are wedge-shaped at the base and taper to a sharp point at the tip. The upper surface is dark green and smooth or slightly rough and sparsely to moderately covered with minute hairs. The lower surface is densely covered with minute, soft, appressed hairs. The margins are coarsely or shallowly toothed. The leaves have a prominent midvein, and a pair of lateral veins that branch off the main vein well above the base and arch upward. The first pair of lateral veins is only slightly more prominent than subsequent pairs.

The inflorescence is occasionally a solitary head, usually an open, branched cluster of 3 to 15 or more flower heads at the end of the stem.

The flower heads are 2½ to 4 wide with disk up to wide. They are on stout stalks that are up to 4 long. There is a whorl of 25 to 30 bracts (involucre) in 2 or 3 overlapping series at the base of the flower head. The involucre is broadly hemispheric in shape and to 1 in diameter. The bracts are loosely spreading or sometimes ascending, and are spreading or bent backward at the tip. They are narrowly lance-shaped to nearly linear, and taper to a sharply-pointed tip. They are hairless or hairy toward the base, and have a fringe of hairs along the margin, at least near the base.

There are 14 to 20 yellow ray florets and 100 or more yellow disk florets.

The fruit is an achene.

 
     
 

Height

 
 

24 to 120

 
     
 

Flower Color

 
 

Yellow ray florets, reddish-brown to purple disk florets

 
     
 

Similar Species

 
 

Rydberg’s sunflower (Helianthus nuttallii ssp. rydbergii) leaves are on shorter stalks, 3 16 to long. The leaf blades are smaller, 1½ to 8 long and 5 16 to 1½ wide. The margins are untoothed or sparingly toothed. The inflorescence has fewer flower heads, no more than 6. The involucre has 30 to 38 bracts. The flower head has fewer disk florets, 60 or more. In Minnesota it is rare, currently verified in only one location.

 
     
 
Habitat
 
 

Dry. Prairies, bluff tops, railroads, roadsides, and open, disturbed areas. Full sun. Sandy soil.

 
     
 
Biology
 
 

Flowering

 
 

June to September

 
     
 

Pests and Diseases

 
 

Sunflower bullet gall midge (Pilodiplosis helianthibulla) makes ¼ in diameter, almost globe-shaped galls on the leaves of plants in the genus Helianthus.

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

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

 
  9/4/2020      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

Common

 
         
 
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)  
  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)  
  Subtribe Helianthinae  
  Genus Helianthus (sunflower)  
       
 

Subordinate Taxa

 
 

 

 
       
 

Synonyms

 
 

Helianthus grosseserratus var. hypoleucus

Helianthus grosseserratus ssp. maximus

Helianthus instabilis

 
       
 

Common Names

 
 

saw-tooth sunflower

sawtooth sunflower

thick-tooth sunflower

 
       

 

 

 

 

 

 

 

 

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, flower cluster, or inflorescence.

 

Glaucous

Pale green or bluish gray due to a whitish, powdery or waxy film, as on a plum or a grape.

 

Involucre

A whorl of bracts beneath or surrounding a 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.

       
Visitor Photos
   

Share your photo of this plant.

This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach one or more photos and, if you like, a caption.

       
MinnesotaSeasons.com Photos
   

Plant

 

sawtooth sunflower

  sawtooth sunflower
       

Flower Head

  sawtooth sunflower   sawtooth sunflower
       

Leaves

  sawtooth sunflower    
       
       

 

Camera

     
Slideshows
   
  Helianthus grosseserratus SAWTOOTH SUNFLOWER
Frank Mayfield
 
  Helianthus grosseserratus SAWTOOTH SUNFLOWER  

 

slideshow

       
Visitor Videos
       

Share your video of this plant.

This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach one or more videos or YouTube links and, if you like, a caption.

       
       
Other Videos
 
       
       
       
       

 

Camcorder


Last Updated:

About Us | Privacy Policy | Contact Us | © 2021 MinnesotaSeasons.com. All rights reserved.