Sun Cup

Sun Cups, Golden-eggs
Taraxia ovata
NATIVE

Description (Jepson, PlantID.net)

• 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

Distribution

• 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

Notes

• Flowers in this genus open in the morning and close in the evening or when it’s cloudy
  • This process is an example of photonasty, a nastic response to light
  • Nastic responses occur when a plant part, such as a flower or leaf, moves in response to a stimulus (Mauseth 2012), e.g., humidity (hydronasty), light (photonasty), temperature (thermonasty), or touch (thigmonasty)
    • Nastic responses are caused by changes in turgor pressure 
    • They are independent of the direction of the stimulus and usually are reversible and repeatable
  • Nastic responses differ from tropic responses
    • Tropic responses are directional growth movements–a plant grows toward or away from a stimulus, e.g., light (phototropism), gravity (gravitropism) or touch (thigmotropism)
    • All plants have tropic responses, but only some plants have nastic responsess
• 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
  • See iNaturalist for observations of this plant
• Flowers February – June

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.

Mauseth, J. 2012. Botany: An Introduction to Plant Biology (5th ed.). Jones & Bartlett Learning. Burlington, Massachusetts.

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.

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

General References

Calflora Database. 2014. Berkeley, California.

Calscape. 2018. California Native Plant Society.

Charters, M.L. 2015. California Plant Names: Latin and Greek Meanings and Derivations.

Charters, M.L. 2017. Southern California Wildflowers: Guide to the Pronunciation of Specific, Generic and Family Names.

Corelli, T. 2004. Flowering Plants of Edgewood Natural Preserve (2nd. ed.). Monocot Press, Half Moon Bay, California.

Dave’s Garden.

Elpel, T.J. 2013. Botany in a Day: The Patterns Method of Plant Identification. HOPS Press, Pony, Montana.

Flora of North America. efloras.org.

Harris, J.G., and M.W. Harris. 2013. Plant Identification Terminology: An Illustrated Glossary. Spring Lake Publishing, Spring Lake, Utah.

Keator, G. 2009. California Plant Families. University of California Press, Berkeley and Los Angeles, California.

Native American Ethnobotany DB.

Regents of the University of California. Jepson eFlora. Jepson Herbarium. University of California, Berkeley.