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| Spurges | ||||||||||||||||||||||
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| Scientific classification | ||||||||||||||||||||||
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| Diversity | ||||||||||||||||||||||
| c.2160 species | ||||||||||||||||||||||
| Type species | ||||||||||||||||||||||
| Euphorbia antiquorum L. | ||||||||||||||||||||||
| Subgenera | ||||||||||||||||||||||
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Chamaesyce | ||||||||||||||||||||||
| Synonyms | ||||||||||||||||||||||
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Chamaesyce |
The spurges make up Euphorbia, a very diverse genus of plants, belonging to the spurge family (Euphorbiaceae). Consisting of about 2160 species, spurges are one of the largest genera in the plant kingdom. The genus is primarily found in the tropical and subtropical regions of Africa and the Americas, but also in temperate zones worldwide. Succulent species originate mostly from Africa, the Americas and Madagascar. There exists a wide range of insular species, namely on the Hawaiian Islands where spurges are collectively known as ʻakoko[verification needed]
The common name "spurge" derives from the Middle English/Old French espurge ("to purge"), due to the use of the plants sap as a purgative.
The botanical name Euphorbia derives from Euphorbus, the Greek physician of king Juba II of Numidia (52-50 BC - 23 AD). He is reported to have used a certain plant, possibly Resin Spurge (E. resinifera), as a herbal remedy when the king suffered from a swollen belly[verification needed]. Carolus Linnaeus assigned the name Euphorbia to the entire genus in the physician\'s honorLinnaeus (1753): p.450.
Juba II himself was a noted patron of the arts and sciences and sponsored several expeditions and biological research. He also was a notable author, writing several scholarly and popular scientific works such as treatises on natural history or a best-selling traveller\'s guide to Arabia. Euphorbia regisjubae (King Juba\'s Euphorbia) was named to honor the king\'s contributions to natural history and his role in bringing the genus to notice.
Contents |
The plants are annual or perennial herbs, woody shrubs or trees with a caustic, poisonous milky sap (latex). The roots are fine or thick and fleshy or tuberous. Many species are more or less succulent, thorny or unarmed. The main stem and mostly also the side arms of the succulent species are thick and fleshy, 15-91 cm (6-36 inches) tall. The deciduous leaves are opposite, alternate or in whorls. In succulent species the leaves are mostly small and short-lived. The stipules are mostly small, partly transformed into spines or glands, or missing.
Like all members of the family Euphorbiaceae, all spurges have unisexual flowers. In Euphorbia these are greatly reduced and grouped into cyathia called pseudanthia. There are also (monoecious) species with male and female flowers on the same plant and those (dioecious) with male and female flowers occurring on different plants. It is not unusual for the central cyathia of a cyme to be purely male, and for lateral cyathia to carry both sexes. Sometimes young plants or those growing under unfavourable conditions are male only, and only produce female flowers in the cyathia with maturity or as growing conditions improve. The bracts are often leaf-like, sometimes brightly coloured and attractive, sometimes reduced to tiny scales. The fruits are three (rarely two) compartment capsules, sometimes fleshy but almost always ripening to a woody container that then splits open (explosively). The seeds are 4-angled, oval or spherical, and in some species have a caruncle.
In the genus Euphorbia succulence in the species has often evolved divergently and to differing degrees. Sometimes it is difficult to decide, and it is a question of interpretation, whether or not a species is really succulent or "only" xerophytic. In some cases, especially with geophytes, plants closely related to the succulents are normal herbs. About 850 species are succulent in the strictest sense. If one includes slightly succulent and xerophytic species, this figure rises to about 1000, representing about 45% of all Euphorbia species.
The latex (milky sap) of spurges acts as a deterrent for herbivores as well as a wound healer. Usually it is white, but in rare cases (e.g. E. abdelkuri) yellow. As it is under pressure, it runs out from the slightest wound and congeals within a few minutes of contact with the air. Among the component parts are many di- or tri-terpen esters, which can vary in composition according to species and in some cases the variant may be typical of that species. The terpen ester composition determines if the latex is slightly or very caustic and irritating to the skin, and especially if in contact with mucous membranes (eyes, nose, mouth) can produce extremely painful inflammation. In experiments with animals it was found that the terpen ester resiniferatoxin had an irritating effect 10,000 to 100,000 times stronger than capsaicin, the "hot" substance found in chillies. Several terpen esters are also known to be carcinogenic.
Therefore handling spurges needs to be done with caution. Latex coming in contact with the skin should be washed off immediately and thoroughly. Partially or completely congealed latex is often no longer soluble in water, but can be removed with an emulsion (milk, hand-cream). With inflammation of a mucous membrane a doctor needs to be consulted. If cutting large succulent spurges in a greenhouse, it has been noticed that vapours from the latex spread and can cause severe irritation to the eyes and air passages several metres away. Caution is therefore required and for example ensure sufficient ventilation. Small children and domestic pets should never come into contact with spurges.
Several spurges are grown as garden plants, among them Poinsettia (E. pulcherrima) and the succulent E. trigona. E. pekinensis (Chinese: 大戟; pinyin: dàjǐ) is used in traditional Chinese medicine, where it is regarded as one of the 50 fundamental herbs. Several Euphorbia species are used as food plants by the larvae of some Lepidoptera (butterflies and moths), including the Giant Leopard Moth. Euphorbias are used in natural medicine to heal cancer,leukemia and other virus caused illnesses.(esula, cyparissias, helioscopia and others) http://www.springerlink.com/content/r125368217774448/ http://www.springerlink.com
According to recent studies of DNA sequence dataSteinmann & Porter (2002), Steinmann (2003), Bruyns et al. (2006) most of the smaller "satellite genera" around the huge genus Euphorbia nest deep within the latter. Consequently these taxa, namely the never generally accepted genus Chamaesyce as well as the smaller genera Cubanthus, Steinmann, van Ee, Berry & Gutiérrez (2007) in Anales del Jardín Botánico de Madrid Elaeophorbia, Endadenium, Monadenium, Synadenium and Pedilanthus were transferred to Euphorbia. The entire subtribe Euphorbiinae now consists solely of the genus Euphorbia.
See List of Euphorbia species for complete list.
The genus Euphorbia is one of the largest and most complex genera of flowering plants and several botanists have made unsuccessfully attempts to subdivide the genus into numerous smaller genera. According to the recent phylogenetic studies, Euphorbia can be divided into 4 subgenera, each containing several not yet sufficiently studied sections and groups. Of these, Esula is the most basal. Chamaesyce and Euphorbia are probably sister taxa but very closely related to Rhizanthium. Extensive xeromorph adaptations in all probability evolved several times; it is not known if the common ancestor of of the cactus-like Rhizanthium and Euphorbia lineages was xeromorphic - in which case a more normal morphology would have re-evolved namely in Chamaesyce - or whether extensive xeromorphism is entirely polyphyletic even to the level of the subgenera.
Light green flowers.jpg
Wood Spurge |
Zypressenwolfsmilch01.jpg
Cypress Spurge |
Euphorbia esula.jpeg
Leafy Spurge |
Euphorbia myrsinites.JPG
Myrtle Spurge |
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E flanaganii ies.jpg
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E meloformis valida ies.jpg
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E obesa symmetrica ies.jpg
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Chamaesyce cyathia.jpg
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Euphorbiaheterophylla1web.jpg
Painted Euphorbia |
E pulcherrima ies.jpg
Poinsettia |
E rivae ies.jpg
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E actinoclada ies.jpg
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E attastoma attastoma ies.jpg
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E confinalis rhodesica ies.jpg
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