Onagraceae (on-uh-GRAY-see-ee)
Iconic Features
- Flower parts in fours
- Inferior ovary
- Often open at dawn or dusk
Description (Jepson)
- Eudicotyledons (eudicots) – a major lineage of flowering plants including most plants traditionally described as dicots and generally characterized by
- 2 seed leaves (dicotyledon)
- Netted (reticulate) leaf venation
- Flower parts in fours and fives
- Pollen grains with 3 pores (tricolpate)
- Vascular bundles in stem arranged in a ring
- Taproot system
- Annuals or herbaceous perennials
- Leaves
- Generally simple (not divided into leaflets) and toothed
- Alternate (1 leaf at each junction with stem), opposite (2 leaves at each junction with stem), or whorled (3 or more leaves at each junction with stem)
- Flowers
- Usually bisexual and radially symmetric
- In parts of 4, with 4 petals and 4 sepals (usually green, outer flower parts)
- Sepals generally fold back (reflex)
- Pollen has cobweb-like (viscin) threads
- Bees in general have specialized electrostatic hairs called scopa (plural, scopae) that store pollen while foraging (Kerstiens 2019)
- Many bees who visit plants in the Evening-primrose family have evolved modified hairs to handle the sticky pollen characteristic of this family (Portman 2017)
- Pollen with viscin threads has been found in only two other, unrelated plant families: in some members of the Heath family (Ericaceae), including Rhododendron, and of the Pea family (Fabaceae) (Sarwar 2007)
- This is an example of convergent evolution
- Sepals, petals, and stamens (male flower parts) fused at base into a cup-like structure (hypanthium)
- Sometimes lengthened into a floral tube
- Ovary inferior (below the attachment of other flower parts)
- Fruit usually a capsule (dry, multi-chambered pod that splits open) with many small seeds
Notes
- Approximately 657 species worldwide, in a wide range of habitats
- Found in California from coastal dunes to alpine regions and in deserts and wetlands
- Includes clarkias, suncups, willowherbs, and fuschias
- Flowers often close at night 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 responses
- Scientific name from the genus Onagra (now Oenothera), from the Greek for “(food of) the ass”
- Distinct from the similarly-named Primrose family (Primulaceae), which includes the common ornamental primrose and shooting stars
- Represented by 11 species at Edgewood
Specific References
Kerstiens, H. 2019, Apr. 3. Charged electrostatic hairs collect pollen granules. Ask Nature. Biomimicry Institute.
Mauseth, J. 2012. Botany: An Introduction to Plant Biology (5th ed.). Jones & Bartlett Learning. Burlington, Massachusetts.
Portman, Z. 2017, Jul. 6. The stickiness of Onagraceae pollen. The Science of Species: Understanding and Identifying the Bees of North America.
Sarwar, A.K.M. 2007, Mar. Pollen Morphology and Its Systematic Significance in the Ericaceae. Dissertation. Graduate School of Agriculture, Hokkaido University, Sapporo, Japan. Pg. 225.
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.
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.
Browse Some Edgewood Plants in this Family
