common sunflower

(Helianthus annuus)

               
Conservation Status

IUCN Red List

not yet assessed

common sunflower

NatureServe

N5 - Secure

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

OBL - Obligate wetland

Midwest

OBL - Obligate wetland

Northcentral & Northeast

OBL - Obligate wetland

Nativity

Native

Occurrence

Widespread

Habitat

Moist to slightly dry. Disturbed sites. Full sun.

Flowering

July to September

     
Flower Color

Yellow ray florets, reddish-brown to purple disk florets

     
Height

20 to 120

     

Identification

This is an erect, annual forb that rises on a single stem from a taproot and fibrous roots. It can be 40 to 120 tall, but is usually no more than 80 in height.

The stem is erect, stout, ridged, light green to reddish-green, and leafy. It is round in cross section and is usually branched above the middle. The cultivated varieties are unbranched. It is moderately covered with short, stiff, ascending hairs. The hairs have a small, blister-like elevation at the base. The hairs on the lower stem often break off, leaving just the expanded base.

There are usually 8 to 25 leaves on the stem. They are on ¾ to 5 long leaf stalks (petioles). The petioles has a channel on the upper (dorsal) surface, and is covered with short, stiff hairs. Only the lowermost leaves are opposite, the rest are alternate. The leaf blades are rough to the touch, like sandpaper. They are egg-shaped to triangular egg-shaped, 4 to 16 long, and 2 to 40 wide. They are wedge-shaped to heart-shaped at the base and taper to a usually sharp point at the tip. They are flat, not folded, and are often slightly drooping. They have 3 main veins, a central midrib and 2 lateral veins that branch from the midrib at the base. The upper and lower surfaces are moderately to densely covered with minute, firm, stiff, loosely appressed hairs. They are also sometimes moderately to densely dotted with stalkless yellow glands. The margins are finely to coarsely toothed, rarely almost untoothed. The leaves become much smaller and shorter stalked as they ascend the stem.

The inflorescence is rarely a solitary flower head at the end of the stem. It is usually an open, branched cluster (panicle) of 2 to 9 flower heads. Each flower head is at the end of a ¾ to 5 long stalk. The flower heads are 3 to 6 in diameter. The cultivated varieties have a single, larger flower head.

The whorl of modified leaves (bracts) at the base of the flower head (involucre) is half globe-shaped, to 1½ long, and to 1½ in diameter. The disk is flat and at least 1¼ in diameter. On cultivated varieties the involucre is longer and much wider, up to 8 or more in diameter. It is composed of 20 to 30 bracts (phyllaries) in 3 or 4 overlapping series. The phyllaries are egg-shaped to lance egg-shaped, ½ to 1 long, and 3 16 to 5 16 wide. They taper to a sharp, slender point at the tip with concave sides along the tip. The tips are usually spreading or bent backward. The outer surface is moderately to densely covered with stiff, short or long hairs and with small, stalkless glands.

There are 17 to 30 ray florets and 150 or more disk florets. Cultivated varieties have up to 100 ray florets and up to 1,000 disk florets. The ray florets are yellow, 1 to 2 long, and sterile. The disk florets are reddish-brown to dark purple, sometimes yellow, and fertile.

The fruit is a dry, one-seeded seed capsule (cypsela). The cypsela is purplish-black, more or less inversely pyramid-shaped, more or less flattened, to 3 16 long, and hairless. There is no tuft of hairs attached to the end.

 
Similar
Species

 


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

Comments

This is the state plant of Kansas.


Taxonomy

Family:

Asteraceae (aster)

 

Subfamily:

Asteroideae

 

Supertribe:

Helianthodae

 

Tribe:

Heliantheae (sunflower)

 
Synonyms

Helianthus annuus ssp. jaegeri

Helianthus annuus ssp. lenticularis

Helianthus annuus ssp. texanus

Helianthus annuus var. lenticularis

Helianthus annuus var. macrocarpus

Helianthus annuus var. texanus

Helianthus aridus

Helianthus lenticularis

 
Common
Names

annual sunflower

common sunflower

Kansas sunflower

mirasol

garden sunflower

sunflower

wild sunflower


 

 

 

 

 

 

 

 

 

 

Glossary

Bract

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

 

Cypsela

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 from the wall of the inferior ovary and also from other tissues derived from the receptacle or hypanthium, does not split open at maturity, but relies on decay or predation to release the contents.

 

Involucre

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

 

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.

 

Petiole

The stalk of a leaf blade or compound leaf that attaches the leaf blade to the stem.

 

Phyllary

An individual bract within the involucre of a plant in the Asteraceae family.

       

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Flower Head

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Leaves

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Petiole

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Stem

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About

Native taprooted annuals to about 1 m tall, leaves essentially ovate, receptacle chaffy, all receptacle bracts lacking long white hairs at tip, pappus of two deciduous scales, flowering during the late season, common in disturbed sites from low to middle elevations, especially abundant along roadsides.

 
     

 

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