Sun Cup

Sun Cup © EKennedy

Sun Cups, Golden-eggs
Taraxia ovata

Description (Jepson,

  • Eudicotyledon
    • Eudicots are a major lineage of flowering plants; see family for general characteristics
  • Evening Primrose Family (Onagraceae)
  • Fleshy, low-growing perennial
    • Grows from a thick taproot
  • Leaves are wide and wavy-edged, with pointed tips
    • Arranged in a basal rosette
    • Prominent white or reddish central veins
  • Flowers
    • Inflorescence (flower arrangement) of single flowers atop long floral tubes
    • Flower parts in fours
      • 4 bright yellow petals
      • 4 sepals (usually green, outer flower parts), which fold back (reflex)
      • 8 stamen (male flower parts), with cobweb-like, sticky pollen
      • Pistil (female flower part) with prominent ball-shaped stigma (pollen-receiving structure) slightly extending beyond the stamens
    • Typical flower stem is absent
      • Instead, the hypanthium (floral cup formed from the fusion of petals, sepals, and stamens) lengthens into a long, sterile tube (≤ 6 in.), which encloses an extension of the ovary
    • Ovary inferior (below the attachment of other flower parts)
  • Fruit is a capsule (a dry, multi-chambered fruit that splits open at maturity) that retains the long, sterile extension of the ovary tip
Flower © EKennedy


  • Native to California
    • Grows in grasslands, generally in clay soil
    • See Calflora for statewide observations of this plant
  • Outside of California, grows on the southwest coast of Oregon
  • Grows at elevations to 5,600 ft.

Uses (San Mateo County Parks prohibits removal of any natural material)

  • Wildlife
    • Pollen source for select species of small bees (Wagner 2007)
      • Pollen has cobweb-like (viscin) threads
      • Many bees who pollinate plants in the Evening Primrose family have evolved specialized hairs to transport the sticky pollen (Thorp 1979)
  • Native people
    • Ate the leaves raw, boiled, or steamed

Name Derivation

  • Taraxia (tar-AX-ia) – referring to the leaves, which are similar to those of hawkbit, Leontodon taraxacoides (now L. saxatilis), in the Sunflower family
    • taraxacoides – from the Greek for “resembling taraxacum,” the genus of the common, non-native dandelion
      • taraxacum – from the Greek taraxia, of disputed origin, possibly from the Persian for “bitter herb” or the Greek for “eye-disorder cure”
  • ovata (oh-VAT-ah) – from the Latin ovatus, “oval,” from ovum, “egg,” referring to the oval-shaped leaves or petals
  • Sun cup – a number of species in the Evening Primrose family with yellow flowers share the common name sun cup


  • Flowers in this genus open at dawn
    • Species in the Evening Primrose family open either at dawn or dusk
    • This process is an example of nyctinasty, which refers to diurnal and nocturnal changes (single or repetitive) exhibited by the leaves and flowers of some plants (van Doorn 2003)
  • Because yellow flowers reflect ultraviolet light more strongly than flowers of other colors, they attract pollinators, like bees, that perceive ultraviolet light (Klomberg 2019)
  • The fertile part of the ovary is often underground
    • Location may protect the developing fruit from browsers (Mitchell 2017)
    • Ants or cracks in the clay soil, where it frequently grows, may aid seed dispersal (Corelli 2005)
  • Since 1840 this species has been placed in various genera, including Oenothera, Taraxia, and Camissonia

At Edgewood

  • Found in grasslands
  • Flowers February – June

See General References

Specific References

Cane, J.H. and S.D. Sipes. 2006. Characterizing floral specialization by bees: Analytical methods and a revised lexicon for oligolecty. N.M. Waser and J. Ollerton (Eds.). Plant-Pollinator Interactions: From Specialization to Generalization. University of Chicago Press, Chicago, Illinois. Pp. 99-122.

Klomberg, Y., et al. The role of ultraviolet reflectance and pattern in the pollination system of Hypoxis camerooniana (Hypoxidaceae). AoB PLANTS 11(5). Oxford Academic.

Mitchell, M. 2017. Onagraceae: Evening-primrose family — Suncups & primroses. Monterey County Wildflowers, Trees, and Ferns — A Photographic Guide.

Thorp, R. 1979. Structural, behavioral, and physiological adaptations of bees (Apoidea) for collecting pollen. Annals of the Missouri Botanical Garden 66: 788-812.

van Doorn, W.G. and U. van Meeteren. 2003, Aug. 1. Flower opening and closure: A review. Journal of Experimental Botany 54: 1801-1812. Oxford Academic.

Wagner, W., P. Hoch, and P. Raven. 2007. Revised classification of the Onagraceae. Systematic Botany Monographs 83: 1-240.