paleleaf woodland sunflower

(Helianthus strumosus)

               
Conservation Status

IUCN Red List

not yet assessed

paleleaf woodland sunflower

NatureServe

N5 - Secure

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

FACU - Facultative upland

Midwest

FACU - Facultative upland

Northcentral & Northeast

FACU - Facultative upland

Nativity

Native

Occurrence

 

Habitat

Dry to moderate moisture. Bottomland forests, upland forests, stream banks, river banks, railroads, roadsides. Full to partial sun.

Flowering

July to October

     
Flower Color

Yellow ray florets, yellow disk florets

     
Height

24 to 72

     

Identification

This is a 24 to 72 tall, erect, perennial forb that rises from a long-creeping rhizome. The rhizome is branched and has tubers at the tips of the branches. It usually forms dense colonies.

The stems are erect and usually solitary, though they sometimes appear in small clumps. They are hairless or sparsely hairy below the inflorescence and are often somewhat covered with a whitish, waxy coating (glaucous).

There are usually 8 to 20 pairs of opposite leaves. Sometimes the leaves near the top of the stem are alternate. The larger leaves are on to 1 long leaf stalks The leaf blades are relatively thick, firm, lance-shaped to narrowly egg-shaped, and flat, not folded longitudinally. They are 2¾ to 7 long and ¾ to 4 wide, 2 to 5 times as long as wide. They are wedge-shaped to almost heart-shaped at the base, and taper to a sharp point at the tip with slightly convex sides along the tip. The upper surface is rough with minute hairs that have a small bump at their base. The lower surface is usually sparsely to densely hairy with soft hairs, but may be hairless or almost hairless and pale green to silvery. The margins are shallowly toothed to untoothed. The leaves have 3 main veins, a midvein and a pair of lateral veins that branch off the main vein just above the base and arch upward. There are also several less prominent lateral veins.

The inflorescence is 3 to 15 flower heads appearing as a single head at the end of the stem and few-headed clusters from the upper leaf axils.

The flower heads are 1½ to 4 wide. There are 8 to 15 yellow ray florets and 35 or more yellow disk florets. The tips of the bracts that form the involucre spread outwards.

The fruit is an achene.

 
Similar
Species

Woodland sunflower (Helianthus divaricatus) leaves are stalkless or on leaf stalks less than 3 16 long. It does not occur in Minnesota.


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

Comments

 


Taxonomy

Family:

Asteraceae (aster)

 

Subfamily:

Asteroideae

 

Supertribe:

Helianthodae

 

Tribe:

Heliantheae (sunflower)

 
Synonyms

Helianthus montanus

Helianthus saxicola

 
Common
Names

pale-leaved woodland sunflower

paleleaf woodland sunflower

rough-leaved sunflower

swollen sunflower

woodland sunflower


 

 

 

 

 

 

 

 

 

 

Glossary

bract

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

 

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.

 

tuber

An underground root (as with dahlias) or stem (as with potatoes), thickened by the accumulation of reserved food (usually starch), which serves for food storage and vegetative propagation.

       

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Uploaded on Aug 22, 2011

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