Spurge
From Freepedia
Spurges (genus Euphorbia) are a very large and variable worldwide plant taxon, belonging to the namesake family (spurge family, or Euphorbiaceae). The name "Euphorbia" comes from a Greek surgeon named Euphorbus, who supposedly used the milky latex of these plants in his potions.
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Description
The genus ranges from small trees, shrubs, vines to herbaceous plants. A significant percentage of these are succulent plant, some of which remarkably resemble cacti despite being unrelated, an example of convergent evolution. To the exception of a few species (i.e. Euphorbia hedytoides or Euphorbia curtisii), this genus is composed of monoecious species.
Spurges have a highly specialized inflorescence: the cyathium, which are reduced unisexual flowers grouped into characteristic pseudanthia. It consists of a central pistillate flower surrounded by five groups of staminate flowers. All flowers are enclosed within an involucre with four marginal glands. The central flower develops before the surrounding male ones, thus each cyathium functions like a protogynous hermaphrodite flower. The glands of the cyathium usually produce nectar, and pollination is mainly zoophilous. Indeed, the cyathium looks so much like a hermaphrodite flower that Linnaeus and other authors interpreted it as a true flower. Lamarck however interpreted the cyathium as an inflorescence and this is now recognized.
Spurges contain an acrid, poisonous milky latex, and some of them are armed with thorns. Most of the spurges yield powerful emetic and cathartic products.
Distribution
The genus is primarily found in the tropical regions of Africa and the Americas, but also in temperate zones. Succulent species are mostly originated from Africa and Madagascar.
Taxonomy
The genus Euphorbia is one of the largest and most complex genera of flowering plants; several botanists have made attempts to subdivide the genus into numerous smaller genera, but to date, these segregate genera have not generally been recognised:
- Ademo Post & Kuntze
- Adenopetalum Klotzsch & Garcke
- Adenorima Raf.
- Agaloma Raf.
- Aklemia Raf.
- Alectoroctonum Schltdl.
- Allobia Raf.
- Anisophyllum Haw.
- Anthacantha Lem.
- Aplarina Raf.
- Arthrothamnus Klotzsch & Garcke
- Bojera Raf.
- Ceraselma Wittst.
- Chamaesyce Raf.
- Characias Gray
- Chylogala Fourr.
- Ctenadena Prokh.
- Cyathophora Raf.
- Cystidospermum Prokh.
- Dactylanthes Haw.
- Dematra Raf.
- Desmonema Raf.
- Dichrophyllum Klotzsch & Garcke
- Dichylium Britton
- Diplocyathium Heinr.Schmidt
- Ditritra Raf.
- Endoisila Raf.
- Epurga Fourr.
- Esula (Pers.) Haw.
- Euforbia Ten., orth. var.
- Eumecanthus Klotzsch & Garcke
- Euphorbiastrum Klotzsch & Garcke
- Euphorbiodendron Millsp.
- Euphorbiopsis H.Lév.
- Euphorbium Hill
- Galarhoeus Haw.
- Kanopikon Raf.
- Kobiosis Raf.
- Lacanthis Raf.
- Lathyris Trew
- Lepadena Raf.
- Leptopus Klotzsch & Garcke
- Lophobios Raf.
- Lyciopsis (Boiss.) Schweinf.
- Medusea Haw.
- Nisomenes Raf.
- Ossifraga Rumph.
- Peccana Raf.
- Petalandra F.Muell. ex Boiss.
- Pleuradena Raf.
- Poinsettia Graham
- Pythius B.D.Jacks.
- Sclerocyathium Prokh.
- Sterigmanthe Klotzsch & Garcke
- Tithymalopsis Klotzsch & Garcke
- Tithymalus Gaertn.
- Torfasadis Raf.
- Treisia Haw.
- Tricherostigma Boiss.
- Tumalis Raf.
- Vallaris Raf.
- Xamesike Raf.
- Zalitea Raf.
- Zygophyllidium (Boiss.) Small
Reference
ITIS - Euphorbia
as of 2002-07-13
