SafePlants

Calylophus hartwegii: Hartweg's Sundrops

Explore the captivating world of Calylophus hartwegii, commonly known as Hartweg's Sundrops or Western Primrose, a delightful addition to arid and semi-arid landscapes.

Considerations for Pets

• This plant grows cup-shaped flowers, which may be tempting for pets to investigate and potentially ingest.

Taxonomy and Nomenclature

• Scientific Name: Calylophus hartwegii (Benth.) P.H. Raven
• Family: Onagraceae (Evening-Primrose Family)
• Common Names: Hartweg's Sundrops, Western Primrose, Hartweg's Evening Primrose, Fendler's Sundrops, Yellow Evening Primrose. It's also locally called buttercup (though this name is generally used for plants in the family Ranunculaceae).
• Synonyms: The text also mentions variations like Oenothera hartwegii and Oenothera hartwegii var. typica.
• Subspecies: Calylophus hartwegii subsp. hartwegii, and Calylophus hartwegii subsp. pubescens (A. Gray) Towner & P.H. Raven

Distribution and Habitat

• Hartweg's Sundrops is native to a range of regions, including Kansas, Oklahoma, Colorado, Arizona, New Mexico, and Texas, as well as parts of Northern Mexico.
• It thrives in hot, dry areas and is drought-tolerant.
• The plant is adaptable to various soil types, including clay, sandy, and caliche soils.

Morphological Characteristics and Growth Habits

• Calylophus hartwegii is described as a somewhat upright, perennial groundcover.
• It features narrow, green to gray-green foliage.
• The plant produces bright to lemon-yellow, cup-shaped flowers that are about 1 inch in size. The flower color fades to orange as they age.
• Stems are described as decumbent or slightly ascending, usually branched.

Bloom Period

• Hartweg's Sundrops typically blooms from June through August.
• The flowers open at dusk and close during the day.

Related Species

• Calylophus berlandieri, Calylophus lavandulifolius and Calylophus toumeyi are also mentioned.