Cleland’s evening primrose

(Oenothera clelandii)

               
Conservation Status

IUCN Red List

not yet assessed

Cleland’s evening primrose

NatureServe

NNR - Unranked

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

Common

Habitat

Dry soils. Prairies, fields, roadsides, and waste places. Full sun. Sandy soil.

Flowering

June to October

     
Flower Color

Yellow

     
Height

16 to 40

     

Identification

This is a 16 to 40 tall, erect, biennial forb that rises from a taproot.

In the first year it forms a 3 to 6 wide rosette of basal leaves. In the second year it sends up a flowering stem. It usually dies after bearing fruit once.

The stems are erect or ascending, seldom branched, light green, and densely covered with white, appressed hairs.

The leaves are alternate, ascending to widely spreading, linear to narrowly lance-shaped or linear-oblong, 1¾ to 3 long, and ¼ to ¾ wide. The upper surface is medium green and sparsely covered with short, white, appressed hairs. The lower surface is paler green and densely covered with short, white, appressed hairs. The margins are mostly untoothed, though sometimes there are barely perceptible teeth near the tip.

The inflorescence is a dense, 4 to 12 long spike of numerous flowers at the end of the stem and branches. The central axis of the stalk (rachis) is densely covered with short, white, appressed hairs.

The individual flowers are stalkless. What appears to be a flower stalk is actually a structure formed by the fused bases of the sepals, petals, and stamens (hypanthium). The hypanthium is yellowish-green and covered with straight, stiff, sharp, appressed hairs. When in bud it is to 13 16 long, widely spreading near the rachis then strongly ascending, with the bud held upright. When in bloom the hypanthium elongates, straightens somewhat, and the flower is held at about a 45° angle.

The flowers are crowded and ½ to 1¼ in diameter when fully open. There are 4 green sepals and 4 yellow petals. The sepals are linear, 3 16 to long, and strongly bent backward along the hypanthium. The petals are yellow, broadly elliptic or egg-shaped, 3 16 to long, and usually pointed at the tip. There are 8 equal stamens, 4 united styles, and a distinctive, 4-lobed, cross-shaped stigma. The flowers open around sunset and on cloudy days, and close by noon. They change from closed to fully open in just one minute. They are pollinated by hawk moths or sphinx moths, which feed on their nectar at night. The hypanthium, petals, and sepals are deciduous, withering and falling off when the fruit is formed.

The fruit is a cylinder-shaped, to 11 16, 4-celled capsule. The capsule is round in cross section, 4-sided with rounded angles, curved near the base, and densely covered with white, appressed hairs. Each cell of the capsule contains two rows of dark brown, egg-shaped seeds.

 
Similar
Species

Fourpoint evening primrose (Oenothera rhombipetala) flower sepals are much larger, to 1 long. The flower petals are much larger, to 1 long.


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

Comments

 


Taxonomy

Family:

Onagraceae (evening primrose)

 

Subfamily:

Onagroideae

 

Tribe:

Onagreae

 

Genus:

Oenothera

 

Section:

Oenothera

 

Subsection:

Candela

 
Synonyms

Oenothera heterophylla var. rhombipetala

Oenothera rhombipetala

 
Common
Names

Cleland’s evening primrose

sand evening-primrose


 

 

 

 

 

 

 

 

 

 

Glossary

Hypanthium

A cup-like tubular structure of a flower formed from the fused bases of sepals, petals, and stamens, that surrounds the pistil. Its presence is diagnostic of many families, including Rose, Gooseberry, and Pea.

 

Linear

Long and narrow with parallel sides, as in a blade of grass.

 

Rachis

The main axis of a compound leaf, appearing as an extension of the leaf stalk; the main axis of an inflorescence.

 

Stigma

The portion of the female part of the flower that is receptive to pollen.

       

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  Cleland’s evening primrose   Cleland’s evening primrose
       
  Cleland’s evening primrose    
       

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  Cleland’s evening primrose   Cleland’s evening primrose
       
  Cleland’s evening primrose    
       

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  Cleland’s evening primrose    
       

Infructescence

  Cleland’s evening primrose   Cleland’s evening primrose
       
       

 

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