The Rosidae
Family Overview - The Myrtales
Onagraceae - the Evening Primrose Family

 
Diversity:  Temperate taxa are herbaceous - often perennial  - with some woody taxa in the tropics.  A 'showy' family adapted to animal pollination (mostly insects and hummingbirds) that includes many common Texas wildflowers ('buttercup' - Oenothera speciosa) - and a suite of ornamentals, including Fuchsia.

Distribution:  Worldwide, but mostly temperate and subtropical with considerable diversity in western North America; global diversity of ca. 640 species in ca. 20 genera.  We have 7 genera with 72 species in Texas, including many common, conspicuous, elements of the local Spring flora.

Floral structure:

 Significant features:  No 'handle' for this family with regard to vegetative structure, but the flower is quite distinctive in that  1) all floral whorls are based on a 4-merous structural pattern, 2) the flowers are epigynous and, 3) the hypanthium in many genera extends well beyond the ovary .
 
   

Oenothera speciosa- a population or - more likely - a single plant since this is a rhizomatous perennial species, and a single flower (right) with yellow hypanthium throat and four stigma lobes reflecting 4-carpels (syncarpous)

 
Oenothera speciosa- side view of flower with hypanthium intact (left) and opened (right).   'Strings' of pollen (right) result from physical linkage of pollen grains in Oenothera via hook-like structures on the pollen grain wall.

Epilobium angustifolium - 'fireweed' of the western U.S. is wind-dispersed via comose seeds (frequent in the family) and therefore poised and ready to take advantage of sunlight provided by forest fires:
 
 

Population
Inflorescence
Flower

Fuchsia species show reflexed sepals and epigyny
 

More information on the Onagraceae


Return to Lecture Notes, the Biology 301 homepage, or the Rosidae page