Euphorbiaceae

Euphorbiaceae
Parts of the candlenut tree
(Aleurites moluccana)
Scientific classification
Kingdom:Plantae
Clade:Angiosperms
Clade:Eudicots
Clade:Rosids
Order:Malpighiales
Family:Euphorbiaceae
Juss.[1]
Subfamilies
Euphorbia characias flowers

The Euphorbiaceae, the spurge family, is a large family of flowering plants. In common English, they are sometimes called euphorbias,[2] which is also the name of a genus in the family. Most spurges such as Euphorbia paralias are herbs, but some, especially in the tropics, are shrubs or trees, such as Hevea brasiliensis. Some, such as Euphorbia canariensis,[3]:206 are succulent and resemble cacti because of convergent evolution.[4] This family occurs mainly in the tropics, with the majority of the species in the Indo-Malayan region and tropical America a strong second. A large variety occurs in tropical Africa, but they are not as abundant or varied as in the two other tropical regions. However, Euphorbiaceae also has many species in nontropical areas such as the Mediterranean Basin, the Middle East, South Africa, and the southern United States.

Description

Cyathia of a Euphorbia (E. baylissii)
Croton cultivar 'Petra'.

The leaves are alternate, seldom opposite, with stipules. 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 plants can be monoecious or dioecious. The radially symmetrical flowers are unisexual, with the male and female flowers usually on the same plant. As can be expected from such a large family,a wide variety exists in the structure of the flowers. The stamens (the male organs) number from one to 10 (or even more). The female flowers are hypogynous, that is, with superior ovaries.

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

The fruit is usually a schizocarp, but sometimes a 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 (toxic substances produced by plants), mainly diterpene esters, alkaloids, glycosides, and ricin-type toxins.

A milky latex is a characteristic of the subfamilies Euphorbioideae and Crotonoideae, and the latex of the rubber tree Hevea brasiliensis is the primary source of natural rubber. The latex is poisonous in the Euphorbioideae, but innocuous in the Crotonoideae. White mangrove, also known as blind-your-eye mangrove latex (Excoecaria agallocha), causes blistering on contact and temporary blindness if it contacts the eyes. Other common names are milky mangrove, buta buta (Malay), and gewa (Bangladesh). The latex of spurge was used as a laxative.

Recent molecular studies have shown that the enigmatic family Rafflesiaceae, which was only recently recognized to belong to order Malpighiales, is derived from within the Euphorbiaceae.[5]

Taxonomy

The Euphorbiaceae family is the fifth largest flowering plant family[6] and has about 7,500 species[7] organised into 300 genera[6], 37 tribes, and three subfamilies.

Uses

A number of plants of the spurge family are of considerable economic importance. Prominent plants include cassava (Manihot esculenta), castor oil plant (Ricinus communis), Barbados nut (Jatropha curcas), and the Para rubber tree (Hevea brasiliensis). Many are grown as ornamental plants, such as poinsettia (Euphorbia pulcherrima). Leafy spurge (Euphorbia esula) and Chinese tallow (Triadica sebifera) are invasive weeds in North America. In medicine, some species of the Euphorbiaceae proved effective against genital herpes (HSV-2).[8]

Vulnerability

Some species, despite their medicinal benefits, are facing the risk of becoming extinct. These include the Euphorbia species E. appariciana, E. attastoma, E. crossadenia, and E. gymnoclada.[9]

References

  1. ↑ Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III" (PDF). Botanical Journal of the Linnean Society. 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. Retrieved 2013-06-26.
  2. ↑ Euphorbia, Merriam Webster Dictionary
  3. ↑ Bramwell, D.; Bramwell, Z. (2001). Wild Flowers of the Canary Islands (2nd ed.). Madrid: Rueda. ISBN 8472071294.
  4. ↑ Natasha Nguyen (2014). "Convergent evolution of cacti and euphorbias". Retrieved 31 March 2007.
  5. ↑ (Davis et al. 2007).
  6. 1 2 Gillespie, Lynn J.; Armbruster, W. Scott (1997). "A Contribution to the Guianan Flora: Dalechampia, Haematostemon, Omphalea, Pera, Plukenetia, and Tragia (Euphorbiaceae) with Notes on Subfamily Acalyphoideae". Smithsonian Contributions to Botany (86): 6. doi:10.5479/si.0081024X.86. Retrieved 21 May 2018.
  7. ↑ "The Plant list: Euphorbiaceae". Royal Botanic Gardens Edinburgh and Missouri Botanic Gardens. Retrieved 31 March 2017.
  8. ↑ LA Betancur-Galvis; GE Morales; JE Forero & J Roldan (2002), "Cytotoxic and Antiviral Activities of Colombian Medicinal Plant Extracts of the Euphorbia genus", Memórias do Instituto Oswaldo Cruz, Vol. 97, No. 4, 2002, pp. 541-546. Retrieved through Bioline International (keywords: herpes simplex - Bioline Code: oc02103)
  9. ↑ Names.cria.org.br
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