MacCart's sundrops
Oenothera hartwegii subsp. maccartii (Shinners) W.L.Wagner & Hoch
MacCart’s sundrops is a perennial subspecies of Oenothera hartwegii, long recorded in the genus Calylophus. Its narrow, wavy-edged leaves and yellow flowers are characteristic of plants from the southern Texas borderlands. As the flowers age, their yellow petals fade toward pale pink or purple. ITIS: Calylophus hartwegii subsp. maccartiiFlora of North America: Oenothera hartwegii subsp. maccartiiFlora of North America: Oenothera hartwegii
Botanical name
Oenothera hartwegii subsp. maccartii (Shinners) W.L.Wagner & Hoch is the accepted combination for the catalog’s Calylophus subspecies. ITIS: Calylophus hartwegii subsp. maccartii
Recognizing the plant
The subspecies usually has a sparse covering of short, close-lying hairs. Leaf blades reach roughly half a centimetre to three-and-a-half centimetres long, often with smaller leaf bundles in their axils. The floral tube measures about 1.7 to 4.5 centimetres, and the petals one to three centimetres long. Flora of North America: Oenothera hartwegii subsp. maccartii
Bloom window
Texas and northeastern Mexico, Flora of North America account
Its regional flowering period extends from March to September. Flora of North America: Oenothera hartwegii subsp. maccartii
Native range
MacCart’s sundrops belongs to the open country of southern Texas and northeastern Mexico. Its range follows the south Texas plains and Rio Grande region into Coahuila, Nuevo León and Tamaulipas. The subspecies grows in grassland on sandy or gravelly ground and limestone, sometimes among yuccas, prickly pears and other dry-country plants. Flora of North America: Oenothera hartwegii subsp. maccartii
Ecological relationships
The Flora of North America specifically notes that MacCart’s subspecies opens early in the afternoon, with pollination occurring during both day and evening. Flora of North America: Oenothera hartwegii
Botanical sources
- ITIS: Calylophus hartwegii subsp. maccartii
- Flora of North America: Oenothera hartwegii subsp. maccartii
- Flora of North America: Oenothera hartwegii
Reviewed 2026-10-11. Seasonal development varies with location and growing conditions.