   #copyright

Oenothera

2007 Schools Wikipedia Selection. Related subjects: Plants

                 iOenothera
   Oenothera erythrosepala
   Oenothera erythrosepala
         Scientific classification

   Kingdom:  Plantae
   Division: Magnoliophyta
   Class:    Magnoliopsida
   Order:    Myrtales
   Family:   Onagraceae
   Genus:    Oenothera
             L.

                                   Species

   About 125, including:
   Oenothera acaulis
   Oenothera albicaulis
   Oenothera argillicola
   Oenothera biennis
   Oenothera brachycarpa
   Oenothera caespitosa
   Oenothera californica
   Oenothera coronopifolia
   Oenothera coryi
   Oenothera deltoides
   Oenothera drummondii
   Oenothera elata
   Oenothera erythrosepala
   Oenothera flava
   Oenothera fruticosa
   Oenothera glazioviana
   Oenothera hookeri
   Oenothera jamesii
   Oenothera kunthiana
   Oenothera laciniata
   Oenothera longissima
   Oenothera macrocarpa
   Oenothera missouriensis
   Oenothera nuttallii
   Oenothera pallida
   Oenothera perennis
   Oenothera pilosella
   Oenothera primiveris
   Oenothera rhombipetala
   Oenothera rosea
   Oenothera speciosa
   Oenothera stubbei
   Oenothera taraxacoides
   Oenothera tetraptera
   Oenothera triloba

   Oenothera is a genus of about 125 species of annual, biennial and
   perennial herbaceous flowering plants, native to North and South
   America. It is the type genus of the family Onagraceae. Common names
   include evening primrose, suncups, and sundrops.

   The species vary in size from small alpine plants 10 cm tall (e.g. O.
   acaulis from Chile), to vigorous lowland species growing to 3 m (e.g.
   O. stubbei from Mexico). The leaves form a basal rosette at ground
   level, and spirally up the flowering stems; they are entire to dentate
   or deeply lobed (pinnatifid). The flowers open in the evening, hence
   the name "evening primrose", and are yellow in most species, but white,
   purple, pink or red in a few; there are four petals. Pollination is by
   Lepidoptera (moths) and bees; like many members of the Onagraceae,
   however, the pollen grains are loosely held together by viscin threads
   (see photo below), meaning that only bees that are morphologically
   specialized to gather this pollen can effectively pollinate the flowers
   (it cannot be held effectively in a typical bee scopa). Furthermore,
   the flowers are open at a time when most bee species are inactive, so
   the bees which visit Oenothera are also compelled to be vespertine
   temporal specialists. The seeds ripen from late summer to fall.

   Oenothera species are used as food plants by the larvae of some
   Lepidoptera species including Schinia felicitata and Schinia florida,
   both of which feed exclusively on the genus, the former exclusively on
   O. deltoides.

   In the wild, evening primroses acts as primary colonizers, springing up
   wherever a patch of bare, undisturbed ground may be found. This means
   that they tend to be found in poorer environments such as dunes,
   roadsides, railway embankments and wasteland. It often occurs as a
   casual, eventually being out-competed by other species.
   An evening primrose cultivated in England
   Enlarge
   An evening primrose cultivated in England
   An evening primrose blossom opening in Pennsylvania
   Enlarge
   An evening primrose blossom opening in Pennsylvania
   Pollen of Oenothera fruticosa (scanning electron microscope image)
   Enlarge
   Pollen of Oenothera fruticosa (scanning electron microscope image)

   The genus Oenothera may have originated in Mexico and Central America.
   During the Pleistocene era a succession of ice ages swept down across
   North America, with intervening warm periods. This was repeated for
   four ice ages, with four separate waves of colonization, each
   hybridizing with the remnants of the previous waves. This generated a
   present-day population that is very rich in genetic diversity, spread
   right across the North American continent.

   It was originally assigned to the genus Onagra, which gave the family
   Onagraceae its name. Onagra (meaning "(food of) onager") was first used
   in botany in 1587, and in English in Philip Miller's 1754 Gardeners
   Dictionary: Abridged. Its modern name Oenothera was published by
   Carolus Linnaeus in his Systema Naturae, also has a donkey-related
   origin, meaning "ass-catcher". In Greek oeno means "donkey", while
   thera means "to catch, trap, pursue". It is believed that the name
   refers to the toxicity of the plant that can be used to trap donkeys
   and other animals. William Baird suggests, however, that oeno could be
   interpreted as "wine" in Greek. He believes that it refers to the fact
   that the root of the edible Oenothera biennis was used as a wine flavor
   additive.

Cultivation and uses

   Young roots can be eaten like a vegetable (with a peppery flavour), or
   the shoots can be eaten as a salad. The whole plant was used to prepare
   an infusion with astringent and sedative properties. It was considered
   to be effective in healing asthmatic coughs, gastro-intestinal
   disorders, whooping cough and as a sedative pain-killer. Poultices
   containing O. biennis were at one time used to ease bruises and speed
   wound healing. One of the common names for Oenothera, "Kings cureall",
   reflects the wide range of healing powers ascribed to this plant,
   although it should be noted that its efficacy for these purposes has
   not been demonstrated in clinical trials.

   The mature seeds contain approximately 7-10 % gamma-linolenic acid, a
   rare essential fatty acid. The O. biennis seed oil is used to reduce
   the pains of premenstrual stress syndrome. Gamma-linolenic acid is also
   said to be effective against breast cancer.

   Evening Primroses are very popular ornamental plants in gardens. For
   propagation, the seeds can be sown in situ from late spring to early
   summer. The plant will grow successfully in fertile soils if competing
   species are kept at bay. Evening primrose species can be planted in any
   ordinary, dry, well-drained garden soil (preferly sandy loam) in an
   open site that is sunny to partly shady. They are fairly
   drought-resistant.

   The first plants to arrive in Europe reached Padua from Virginia in
   1614 and were described by the English botanist John Goodyer in 1621.
   Some species are now also naturalized in parts of Europe and Asia, and
   can be grown as far north as 65° N in Finland. The UK National Council
   for the Conservation of Plants and Gardens, based at Wisley, maintains
   an Oenothera collection as part of its National Collections scheme.

   Retrieved from " http://en.wikipedia.org/wiki/Oenothera"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
