toothed evening primrose

(Oenothera serrulata)

Conservation Status
toothed evening primrose
  IUCN Red List

not listed


N5? - Secure

SNR - Unranked


not listed


Toothed evening primrose is an erect, perennial forb that rises up to 24 on usually clustered stems from a taproot rhizome caudex.

The stems are erect or recline on the ground with the tips ascending. They are grayish or whitish, at least above the middle, due to a covering of white, straight, stiff, appressed hairs. The are sometimes somewhat woody near the base.

The leaves are alternate, ¾ to 2 long, and less than ½ wide, linear, oblong, or narrowly inversely lance-shaped with the attachment at the narrow end. The margins are sometimes untoothed but are more often toothed with minute, sharp, forward-pointing teeth. The upper surface is hairy or sparsely hairy. The lower surface is hairy. The leaves fold in the midday sun in order to conserve water.

The inflorescence is a solitary flower borne in the upper leaf axils.

The flowers are to 1 wide and stalkless. The 4 petals are bright yellow and are fused at the base into a funnel-shaped, to ½ long hypanthium. The hypanthium is 4-angled and hairy, sometimes only on the angles. There are 8 stamens. The flowers open in the morning.

The fruit is a linear capsule, ½ to 1 long, 4-angled with rounded angles, and whitish due to a covering of white, straight, stiff, appressed hairs.




Up to 24


Flower Color


Bright yellow


Similar Species


Dry. Prairies, plains, bluffs. Full sun.




June to July




Distribution Map



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









  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 (flowering plants)  
  Superorder Rosanae  
  Order Myrtales (myrtles, evening primroses, and allies)  


Onagraceae (evening primrose)  
  Subfamily Onagroideae  
  Tribe Onagreae  


Oenothera (evening primroses, sundrops, and beeblossoms)  
  Section Calylophus  
  Subsection Calylophus  

Toothed evening primrose was originally placed in the genus Oenothera when it was first described by Thomas Nuttall in 1818. In 1964 it was separated into its own genus, Calylophus, by Peter Raven based strictly on morphological features, including a more or less shield-shaped stigma that was entire or only shallowly and broadly four-lobed. More recently, molecular analysis of the evening primrose (Onagraceae) family (W.L. Wagner et al., 2007) showed that toothed evening primrose should be regarded as representing one of fourteen specialized groups within Oenothera. It is now classified as section Calylophus.


Subordinate Taxa






Calylophus australis

Calylophus serrulatus

Meriolix intermedia

Meriolix oblanceolata

Meriolix serrulata

Oenothera serrulata var. typica


Common Names


halfshrub calylophus

halfshrub sundrop

plains yellow primrose

serrateleaf eveningprimrose

toothed evening primrose

yellow evening-primrose

yellow sundrops












The upper angle where the leaf stalk meets the stem.



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.



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

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  toothed evening primrose   toothed evening primrose
  toothed evening primrose    


  toothed evening primrose   toothed evening primrose
  toothed evening primrose    


  toothed evening primrose   toothed evening primrose



  Oenothera perennis SMALL SUNDROPS
Frank Mayfield
  Oenothera perennis SMALL SUNDROPS  



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Other Videos
  Botanist Jim Allison: flowering Sun Drops and Winged Elm
Panola Mountain

Uploaded on Jun 12, 2011

11 June 2011, Panola Mountain outcrop exploration with botanist Jim Allison: Here, Jim is explaining the Sun Drops. These are located in many spots atop the outcrop. Also identified, the Winged Elm




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