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 the stamens
      • Typical flower stem is absent
        • Instead, the short, shallow floral cup (hypanthium) 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 (Picking or removing any natural material from public land is illegal)

        • 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)
          • Specific plant-insect association is called oligolecty, from the Greek olígos-, “few” and eklektós, “chosen”
        • 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 Sipes, S.D. 2006. Characterizing floral specialization by bees: Analytical methods and a revised lexicon for oligolecty. Plant-Pollinator Interactions: From Specialization to Generalization. Ed. N.M. Waser and J. Ollerton. 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, Volume 11, Issue 5, October 2019, plz057.

                    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(4), 788-812.

                        van Doorn, W.G. and van Meeteren, U. 2003, Aug. 1. Flower Opening and Closure: A Review. Journal of Experimental Botany, 54: 389, pp.1801–1812.

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