Onagraceae Explained

The Onagraceae are a family of flowering plants known as the willowherb family or evening primrose family. They include about 650 species of herbs, shrubs, and trees^[1] in 17 genera.^[2] The family is widespread, occurring on every continent from boreal to tropical regions.

The family includes a number of popular garden plants, including evening primroses (Oenothera) and fuchsias (Fuchsia). Some, particularly the willowherbs (Epilobium), are common weeds in gardens and rapidly colonize disturbed habitats in the wild. One such species is fireweed (Chamaenerion angustifolium).

The family is characterised by flowers with usually four sepals and petals; in some genera, such as Fuchsia, the sepals are as brightly coloured as the petals.

The seeds are generally very small. In some genera, such as Epilobium, they have tufts of hairs^[3] and are dispersed on the wind. In others, such as Fuchsia, the seeds develop in juicy berries dispersed by animals. The leaves are commonly opposite or whorled, but are spirally arranged in some species; in most, they are simple and lanceolate in shape. The pollen grains in many genera are loosely held together by viscin threads. Most bees cannot collect it, and only bees with specialized morphologies can effectively pollinate the flowers; nearly all bee taxa that visit the flowers are oligoleges specialized on the family Onagraceae.

The family was named after the genus Onagra (now known as Oenothera) in 1836 by John Lindley in the second edition of A Natural System of Botany.

Genera

Subfamily Ludwigioideae

• Ludwigia L.^[4]

Subfamily Onagroideae

Tribe Circaeeae Circaea L. Fuchsia L.^[5] Hemifuchsia ^[6] Tribe Epilobieae Chamaenerion Ség. Epilobium L.^[7] Tribe Gongylocarpeae Gongylocarpus Schltdl. & Cham.^[8] Tribe Hauyeae Hauya DC.^[9] Tribe Lopezieae Lopezia Cav. Megacorax Elizondo et al.^[10] Tribe Onagreae Calylophus Spach (= Oenothera)^[11] Camissonia Link Camissoniopsis W.L.Wagner & Hoch Chylismia (Torr. & A.Gray) Raim. Chylismiella (Munz) W.L.Wagner & Hoch Clarkia Pursh Eremothera (P.H.Raven) W.L.Wagner & Hoch Eucharidium Fisch. & C.A.Mey. Eulobus Nutt. ex Torr. & A.Gray Gaura L. (= Oenothera) Gayophytum A.Juss. Neoholmgrenia W.L.Wagner & Hoch Oenothera L. Taraxia (Torr. & A.Gray) Raim. Tetrapteron (Munz) W.L. Wagner & Hoch Xylonagra Donn.Sm. & Rose^[12]

Several genera are synonymized in the classification presented above, in particular Calylophus and Gaura, which have both been absorbed into Oenothera but appear often in the literature as belonging to the previous genera.

External links

• Smithsonian Institution: Onagraceae classification

Notes and References

1. http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=10630 Onagraceae.
2. 25064249. Tribal Relationships within Onagraceae Inferred from PgiC Sequences. Systematic Botany. 32. 2. 348–356. Ford. V. S.. Gottlieb. L. D.. 2007. 10.1600/036364407781179725. 86207688.
3. http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=111844 Epilobium.
4. Web site: GRIN Genera of Onagraceae subfamily Ludwigioideae . Germplasm Resources Information Network . United States Department of Agriculture . 2010-10-29.
5. Web site: GRIN Genera of Onagraceae tribe Circaeeae . Germplasm Resources Information Network . United States Department of Agriculture . 2010-10-29.
6. Christian Geier, Johannes M. Bouchal, Silvia Ulrich, Dieter Uhl, Torsten Wappler, Sonja Wedmann, Reinhard Zetter, Jürg Schönenberger, Friðgeir Grímsson (2023). Potential pollinators and paleoecological aspects of Eocene Ludwigia (Onagraceae) from Eckfeld, Germany. Palaeoworld,2023, ISSN 1871-174X, https://doi.org/10.1016/j.palwor.2023.07.003.
7. Web site: GRIN Genera of Onagraceae tribe Epilobieae . Germplasm Resources Information Network . United States Department of Agriculture . 2010-10-29.
8. Web site: GRIN Genera of Onagraceae tribe Gongylocarpeae . Germplasm Resources Information Network . United States Department of Agriculture . 2010-10-29.
9. Web site: GRIN Genera of Onagraceae tribe Hauyeae . Germplasm Resources Information Network . United States Department of Agriculture . 2010-10-29.
10. Web site: GRIN Genera of Onagraceae tribe Lopezieae . Germplasm Resources Information Network . United States Department of Agriculture . 2010-10-29.
11. Web site: Oenothera . Germplasm Resources Information Network . United States Department of Agriculture . 2013-01-29.
12. Web site: GRIN Genera of Onagraceae tribe Onagreae . Germplasm Resources Information Network . United States Department of Agriculture . 2010-10-29.