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  Euphorbiaceae

The *Spurge </topic/spurge-2> family* (*Euphorbiaceae*) is a large
family of flowering plants </topic/flowering-plant> with 240 genera and
around 6,000 species. Most are herbs </topic/herb>, but some, especially
in the tropics </topic/tropics>, are also shrubs </topic/shrub> or trees
</topic/tree>. Some are succulent </topic/succulent> and resemble cacti
</topic/cactus>.

This family occurs mainly in the tropics, with the majority of the
species in the Indo-Malayan </topic/indomalaya-ecozone> region and
tropical America </topic/the-americas> a good second. There is a large
variety in tropical Africa, but it is not as abundant or varied as in
these two other tropical regions. However, /Euphorbia/ also has many
species </topic/species> in non-tropical areas such as the Mediterranean
</topic/mediterranean-sea>, the Middle East </topic/middle-east>, South
Africa </topic/south-africa> and southern USA.

The leaves </topic/leaf> are alternate, seldom opposite, with stipules
</topic/stipule>. They are mainly simple, but where compound, are always
palmate, never pinnate. Stipules may be reduced to hairs, glands, or
spines, or in succulent species are sometimes absent.

The radially symmetrical flowers </topic/flower> are unisexual, with the
male and the female flowers usually occurring on the same plant. As can
be expected from such a large family, there is a wide variety in the
structure of the flowers. They can be monoecious
</topic/dioecious-plant> or dioecious </topic/dioecious-plant>. The
stamens </topic/stamen> (the male organs) can number from 1 to 10 (or
even more). The female flowers are hypogynous, that is, with a superior
ovary </topic/ovary-plants>.

Cyathia of a Euphorbia </topic/e-baylissii-ies-jpg-1>
Enlarge </topic/e-baylissii-ies-jpg-1>
Cyathia of a /Euphorbia/

The genera in tribe Euphorbieae </topic/euphorbieae>, subtribe
Euphorbiinae </topic/spurge-2> (/Euphorbia </topic/spurge-2>/ and close
relatives) show a highly specialized form of pseudanthium
</topic/pseudanthium> ("false flower" made up of several true flowers)
called a *cyathium </topic/cyathium-1>*. This is usually a small
cup-like involucre </topic/cupule-3> consisting of fused together bracts
and peripheral nectary glands, surrounding a ring of male flowers, each
a single stamen </topic/stamen>. In the middle of the cyathium stands a
female flower: a single pistil </topic/carpel> with branched stigmas.
This whole arrangement resembles a single flower.

The fruit </topic/fruit> is usually a schizocarp </topic/schizocarp>,
sometimes a drupe </topic/drupe>. A typical schizocarp is the *regma*, a
capsular fruit with three or more cells, each of which splits open at
maturity into separate parts and then breaks away explosively,
scattering the small seeds.

The family contains a large variety of phytotoxins </topic/phytotoxin-2>
(toxic substances produced by plants), mainly diterpene esters
</topic/ester>, alkaloids </topic/alkaloid>, glycosides
</topic/glycoside>, and ricin </topic/ricin>-type toxins.

A milky sap </topic/sap> or latex </topic/latex-11> is a characteristic
of the subfamilies Euphorbioideae and Crotonoideae. This milky sap is
poisonous </topic/poison-bell-biv-devoe-song> in the Euphorbioideae,
innocuous in the Crotonoideae. *White mangrove* (/Excoecaria
agallocha/), or *Blind-Your-Eye Mangrove* sap causes blistering on
contact and temporary blindness if it contacts the eyes. Other common
names are *Milky Mangrove*, *Buta Buta* (Malay </topic/malay-language>),
*Gewa* (Bangladesh </topic/bengali-language>). The sap of spurge
</topic/spurge-2> was used as a purgative </topic/laxative>.

Recent molecular studies have shown that the enigmatic family
Rafflesiaceae </topic/rafflesiaceae>, which was only recently recognized
to belong to order Malpighiales </topic/malpighiales>, is derived from
within Euphorbiaceae (Davis et al. 2007).


    Uses

A number of plants of the Spurge family are of considerable economic
importance. Prominent plants include Manioc </topic/cassava>, the Castor
bean </topic/castor-oil-plant>, and the Para rubber tree
</topic/para-rubber-tree>. Many are grown as ornamental plants
</topic/ornamental-plant>, such as Poinsettia </topic/poinsettia>
(/Euphorbia pulcherrima/). Leafy spurge </topic/euphorbia-esula-1>
(/Euphorbia esula/) is an invasive weed in North America.


    References

    * Charles C. Davis, Maribeth Latvis, Daniel L. Nickrent, Kenneth J.
      Wurdack, David A. Baum. 2007. Floral gigantism in Rafflesiaceae.
      Science Express, published online January 11, 2007 (online
      abstract here
      <http://www.sciencemag.org/cgi/content/abstract/1135260>).
    * International Euphorbia Society
      </topic/international-euphorbia-society>
    * Data from GRIN Taxonomy
      <http://www.ars-grin.gov/~sbmljw/cgi-bin/family.pl?433>
    * Euphorbiaceae <http://delta-intkey.com/angio/www/Euphorbi.htm> in
      L. Watson and M.J. Dallwitz (1992 onwards). The families of
      flowering plants: descriptions, illustrations, identification,
      information retrieval. <http://delta-intkey.com/angio/>
      http://delta-intkey.com

