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Hartweg's sundrops

Scientific Name: Calylophus hartwegii ssp. fendleri

Family: Onagraceae

Category: Dicot

Growth: Subshrub, Forb/herb

Duration: Perennial

Other Names:

       

Calylophus hartwegii

Calylophus hartwegii, also known as Hartweg's sundrops or Western Primrose, is a flowering plant belonging to the Evening-Primrose Family.

Taxonomy and Nomenclature

  • Scientific Name: Calylophus hartwegii (Benth.) P.H. Raven
  • Family: Onagraceae (Evening-Primrose Family)
  • Synonyms: Oenothera hartwegii (implied through mentions of older classifications)
  • Subspecies:
    • Calylophus hartwegii subsp. hartwegii
    • Calylophus hartwegii subsp. pubescens (A. Gray) Towner & P.H. Raven
    • Calylophus hartwegii fendleri

Distribution and Habitat

Hartweg's sundrops is native to the southwestern United States and parts of northern Mexico, including:

  • Kansas
  • Oklahoma
  • Colorado
  • Arizona
  • New Mexico
  • Texas
  • Northern Mexico

It thrives in hot, dry areas with full sun to part shade, and tolerates various soil types including clay, sandy, and caliche.

Morphological Characteristics and Growth Habits

  • It is described as a somewhat upright, perennial groundcover.
  • The plant has narrow, green to gray-green foliage.
  • Flowers are cup-shaped, bright to lemon yellow, approximately 1 inch in size.
  • The flowers may fade to orange as they age.
  • Stems can be decumbent or slightly ascending, usually branched.

Quirky Facts

  • The flowers open at dusk and close during the day.
  • The plant has modified leaves (sepals) right below the petals, which have a keel near the tip.
  • Hartweg's sundrops bloom from June through August.

Further Information

  • Monrovia's Hartweg's Sundrops: Monrovia plants
  • Encyclopedia of Life: Encyclopedia of Life
  • Native Plant Information Network (NPIN)
  • United States Department of Agriculture (USDA)