Difference between revisions of "Euphorbia"

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Euphorbia (classical name; said by Pliny to be in honor of King Juba's physician; possibly from the Greek for fat). Eupharbiaceae. Milkweed (improperly) Wolfs-milk. Spurge. The last name, most often applied to the genus as a whole, belongs more properly to the common herbaceous species and especially to E. Lathyris. Of very diverse habit, from succulent cactus- like trees to low or prostrate herbaceous weeds; planted mostly in the open, but some kinds grown under glass as oddities and some as florist's plants.
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The genus is characterized by the single pedicellate, pistilate fl. without floral envelopes, or with only a rudimentary calyx, surrounded by numerous staminate fls., each consisting of a single stamen separated from its pedicel only by a joint; the whole infl. surrounded by a more or less cup-shaped involucre with 5 lobes and 1-5 glands is called a cyathium. The involucre is regular or nearly so; the glands free from one another: the fr. an explosive caps., with 3 carunculate seeds; the staminate fls. are usually subtended by minute bracts. — One of the largest plant genera, of not less than 700 and probably over 1,000 species, occurring in most temperate and tropical regions. Many are desert plants and the greater number grow in dry and sterile places.
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Euphorbia is distinguished from the nearest related genera, Pedilanthus and Synadenium, by its regular or nearly regular involucre, which in Pedilanthus is protuberant on one side of the base and contains the glands, and by the free involucral glands which in Synadenium are united into a ring. Some of the fleshy species are very similar to succulent cacti and Asclepiadaceae. One long grown under the name of E. pendula, Boiss., is a Sarcostemma according to N. E. Brown. For E. tithymaloides. see Pedilanthus; for E. Grantii, Hort.. and E. arborea, Hort., see Synadenium.
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Monographed by Boissier in DeCandolle's Prodromus, 15, pt. 2 (1862). See local floras and Norton, Kept. Mo. Bot. Card. 11, for native species. Sec also Fobe, in Monatsschrift fur Kakteenkunde, 8:42 (1898) and Berger, Sukkulente Euphorbien, a manual of the cactus-like species in cultivation. The recent work of N. E. Brown of Kew in Flora of Tropical Africa and Flora Capensis describes and gives keys to practically all the African species, which include nearly all the succulent ones, both wild and cultivated. Although the vegetative form varies remarkably, so that the various sections of the genus are considered of generic rank by many authors, the floral characters are very similar and so inconspicuous as to be of little importance generally in a horticultural work.
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Most of the species have abundant milky juice, and the cactiform kinds have been thus distinguished from cacti, but many cacti also have milky juice. The juice of many species is acrid-poisonous, especially if it comes in contact with mucous membranes or open sores. The juice from some of the species is used in medicine as a purgative.
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Many of the fleshy species are cultivated by lovers of succulents for their curious shapes; and a few are valuable for their ornamental foliage. The flowers are usually too minute to be noticeable. Some, like E. corollata (Fig. 1437), E. maculata, E. Cyparissias and E. marginata, are weeds in America, but not troublesome. The great majority of the species are insignificant herbs. The species are remarkably free from injurious insects, and are rarely attacked by a few fungi.
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The fleshy species are grown much the same as cacti, but the culture is less difficult, and they do well with warmer treatment. In winter they are kept in a dry and cool house, 50° to 55° F., with good light and little water. Drips must be carefully avoided. In summer the pots should be plunged outdoors in hot dry situations, with a moderate supply of water and especially good drainage. It is better to protect them from continued rain, but most species do well without this. The more fleshy species, like E. Caput- Medusae, E. mammillaris, and E. meloformis, require more heat and better care than the others. They have to be watered with great care in winter. The air of most greenhouses is too damp for them if the requisite low temperature is maintained. The winter conditions of air and temperature in ordinary living - rooms make them ideal for the succulent euphorbias. Species like E. neriifolia need water in the growing season and dry Conditions after the flower is at leaves fall. The shrubby species, like E. atropurpurea and E. dendroides, do well with the treatment of the more fleshy kinds. See D. A. W. and F. S. Curtis, in Sharon Cactus Guide, March and May, 1897.
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The few hardy species of ornamental value make good border plants or are suitable for the rockery. E. epithymoides usually known in gardens as E. polychroma, is one of the best herbaceous perennials, forming a hemispherical clump with beautiful yellow foliage of different shades when in bloom. E. palustris and related species are similar but erect and not compact.
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The succulent species can nearly all be propagated by cuttings. These are taken best in early summer, allowed to dry somewhat and then planted in sand, charcoal or a mixture of these. Coal-ashes are used effectively by some. When seeds can be procured, they may be used in propagation. Grafting, as is sometimes practised with cacti, is possible. Potting soil need not be rich. A coarse sandy loam, or, some say, any kind of soil will do.
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E. pulcherrima and E. fulgens are good winter-flowering greenhouse plants, and require special treatment. E. fulgens succeeds well in the warmest parts of the house, in pots, or best planted out like roses and trained upon the wall or strings. It is propagated from cuttings taken in June, when the old plants have started to grow, kept in a warm frame until rooted, and then kept growing with heat, any transfers being made with as little root disturbance as possible. If stocky show plants are wanted, several cuttings may be planted in one pot and checked two or three times during summer by repotting, and kept pinched back freely to secure branches. They are best kept cooler when in flower, but are very sensitive to cold or sudden changes in temperature. After flowering they are kept dry for a few months. For the cut sprays they are best grown from cuttings each year. They last very well when cut.
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The culture of the poinsettia is very similar. To secure plants with large heads, the general plan is to grow from cuttings annually, but the old plants may be continued. Old plants that have been resting may be introduced to heat and moisture in late spring, and will soon give a liberal supply of cuttings, which are usually taken from the young wood. Successive sets of cuttings may be made at later periods if different- sized plants are wanted. When well started, the potted plants are plunged outdoors till September, with plenty of water, light and sunshine and good drainage. They do well in rich heavy loam in 5-7-inch pots. They are liable to drop their leaves if exposed to cold or other unfavorable conditions, lii autumn they are transferred to the greenhouse, with moderate temperature. When the bracts begin to appear, give more heat and some manure water to expand them. When in flower, reduce the temperature to preserve them longer. After flowering the pots may be stowed away in a dry warm place till spring,—under the benches will do. When the buds are cut the great objection is that they wilt easily. This may be obviated by keeping them in water for a few days before using. See Grieve, G.C. III. 9:106, and Hatfield in Garden and Forest 9:496. See article Poinsettia for further treatment.
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The following have been reported in cult. in Eu. but are not in the American trade.
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E. aggregata Berger. A succulent grown like E. cereiformis.— E. aleppica. Linn. Annual of Tithymalus section.—E. amygdaloides, Linn. Perennial and almost woody. Common in England.— E. angularis, Klotzsch (E. fimbriata, Hort.). A 3-5-angled succulent. —E. aphylla, Brouss. Semi-succulent shrub, near E. Tirucalli. Gt. 37:277.—E. arbuscula, Balf. Semi-succulent shrub near E. xylo-phylloides.—E. balsamifera. Ait. Tropical shrub: Lvs. at end of branches. Allied to E. dendroides.—E. Berthelotii, C. Bolle. Subtropical shrub allied to E. Regis-Jubae; name used incorrectly in the trade.—E. Bojeri, Hook. (E. Breonii). Semi-succulent, slender, spiny shrub near E. splendens. Hook. B.M. 3527.—E. bubalina, Boiss. (Section Treisia). Low, slender, spineless succulent, leafy at apex. R.B. 209 (as E. oxystegia).—E. Cactus, Erenh. Succulent, spiny 3-angled shrub, near E. Hermentiana.—E. cattimandoo, Ell. Small, succulent, spiny, 5-angted tree.—E. cervicornis, Boisa.=E. hamata.—E. chamaesyce, Linn. Low, opposite-lvd. herb with corolla-like cyathia in clusters.—E. characias. Linn. Umbellate perennial herb near E. Wulfenii. Gn. 59, p. 447. G.C. II. 13:657.—E. collelioides, Benth. Low Mexican shrub: Lvs. opposite. Plants grown under this name may be E. pteroneura. —E. Dinteri, Berger. Spiny, 6-8-angled succulent shrub often grown under names of E. virosa and E. tetragona.—E. Dregeana, Mey. Spineless, almost Iea6ess shrub, near E. Tirucalli.—E. enopla, Boisa. Spiny succulent near E. heptagona, and confused with it.—E. erosa, Willd. Spiny succulent, near E. mammillaris. —E. falcata, Linn. Annual herb, near E. Aleppica.—E. fimbriata, Hort.=E. angularis.—E. hamata, Sweet (E. cervicornis, Boiss.). Low succulent shrub, leafy at apex, near E. clandestina.—E. helicothele, Lem. Spiny, succulent tree, leafy at apex, near E. neriifolia. I.H. 4, p. 100, desc.—E. helioscopia. Linn. Umbellate annual (Section Tithymalus). Rept. Mo. Bot. Gard. 11: pl. 26.—E. Intisy, Drake. Semi-succulent tropical shrub, near E. Tirucalli.—E. Logascae, Spreng. Annual, near E. pilosa.—E. Laro, Drake. Semi-succulent shrub near E. Tirucalli.—E. laurifolia, Juss. Tropical shrub, leafy at ends of branches, near E. atropurpurea.—E. Ledienii, Berger. Spiny succulent, near E. virosa, grown under the names of E. pentagona, E. coerulea, and K. coerulescens. B.M. 8275.—-E. Lemaireana, Boiss. Spiny succulent. Near E. grandicornis.—E. lophogona. Lam. Succulent with fringed angles, near E. Fournieri. B.M. 8076.—E. macroglypha, Lem. Spiny, 3-anglcd succulent.—E. Marlothii, Pax= E. Montieri.—E. mauritanica. Linn. Semi-succulent shrub. Near E. Tirucalli.—E. melilfera. Ait. Tree, leafy at branch ends. Near E. dendroides. B.M. 1305.— E. Montieri. Hook. (E. Marlothii, Pax ). Succulent shrub, leafy at the apex, of Section Pseud-euphorbium. B.M. 5534.—E. Morinii, Berger. Spiny succulent, near E. cereiformis.—E. multiceps, Berger. Succulent. Near E. Caput-Medusae.—E. nivulia. Ham. Spiny, succulent shrub, leafy at apex. Near E. neriifolia.—E. Nylkae, Pax. Succulent tree with 2-angled joints.—E. obesa. Hook. Succulent. Near E. meloformis. B.M. 7888.— E. obtusifolia, Poir. Semi-succulent shrub. Near E. Tirucalli.—E. officinarum, Linn. Succulent, spiny, 9-13-angled shrub. Near E. Beaumieriana.—E. Paralias, Linn. Perennial herb of Section Tithymalus.—E. parvimamma, Boiss. Low succulent, without spines. Near E. Caput-Medusae.—E. Phillipsiae, N. E. Br. Succulent, spiny, 9-angled shrub. Near E. Beaumierana.—E. pilulifera. Linn. Low annual with opposite Lvs. and inconspicuous cyathia in clusters: glands appendaged.—E. piscatoria, Ait. Tropical shrub: narrow Lvs. at end of branches. Near E. Regis- Jubae.—E. plumerioides, Teysmann. Tropical shrub similar to the previous one.—E. procumbent. Mill. (E. pugniformis, Boiss.). Succulent, not spiny. Near E. Caput-Medusae. B.M. 8082. R.B. 161.—E. punicea, Swartz. Tropical shrub. Near E. atropurpurea. B.R. 190. B.M. 1961. L.B.C. 20:1901. G.C. II. 15:529. —E. pyrifolia. Lam. Semi-succulent shrub, leafy at the apex. Near E. lophogona. — E. Sapinii, De Wild. Slender, spiny succulent. Near E. cereiformis. G.C. III. 45:66.—E. Schimperi. Presl. Semi-succulent shrub. Near E. Tirucalli.—E. Schimperiana, Hochst. An African annual of Section Tithymalus. This name perhaps used erroneously for E. Schimperi.—E. Scolopendria, Don=E. stellata..— E. scopiformis, Boiss. = E. serpiformis. — E. serpiformis, Boiss. Section Arthrothamnus. Slender-branched semi-succulent shrub with opposite, rudimentary Lvs.—E. Sibthorpii, Boiss. Perennial herb. Near E. Wulfenii.—E. Sipolinii, N. E. Br. Slender succulent shrub with decurrent lf.-bases. Near E. pteroneura.—E. spinosa. Linn. Umbellate sub-shrub or herb of S. Eu. Section Tithymalus.—E. stapeliformis, Hort. =E. stapelioides, Boiss.(?). A plant near E. bupleurifolia.— E. Stapfii, Berger. Spiny, succulent, 4-angled shrub.—E. stelIaespina, Haw. Spiny 10-13-ribbed succulent. Near E. cereiformis. —E. stellata. Wind. (E. uncinata, DC., referred here according to N. E. Br.). Spiny succulent with branches V-shaped in cross- section, and clustered on a short thick st.—E. tetragona. Haw. Spiny, succulent 4-angled tree. R.B. 39.—E. trigona, Haw. Spiny, succulent, 3-angled shrub, near E. antiquorum.—E. tuberculata, Jacq. Low succulent, near E. Caput-Medusae.—E. uncinata -—K. stellata.
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Other names used but not classified: E. Amelia, Hort.—E. articulata, Hort.—E. aurelia, Hort. (E. Amelia?).—E. Caput Commelinii, Hort. (E. Caput-Medusae?)—E. Caput-odorata, Hort.—E. Caput-Simiae, Hort.—E. capensis, Hort. (succulent).—E. colubrina, Hort.—E. cylindrica, Hort.—E. dentata, Hort.—E. de Smetiana, Hort.—E. erecta, Hort.—E. funalis, Hort.—E. gardeniaefolia, Hort. —E. gracilis, Hort.—E. Houlletiana, Hort.—E. Houlletii, Hort.—E. longifolia, Hort.—E. mangador, Hort. (E. mogador, Hort.?).—E. Milleri.—E. obtusa, Hort.—E. pavoensis, Hort.—E. pulchra., Hort. —E. Pulletiana, Hort.—E. Rebutii, Hort.—E. sahariensis, Hort.— E. waltoniensis,, Hort. J. B. S. Norton.
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Revision as of 08:57, 1 October 2009


Read about Euphorbia in the Standard Cyclopedia of Horticulture 

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Euphorbia cf. serrata
Euphorbia cf. serrata
Plant Info
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Sublass: Rosidae
Order: Malpighiales
Family: Euphorbiaceae
Subfamily: Euphorbioideae
Tribe: Euphorbieae
Subtribe: Euphorbiinae
Genus: Euphorbia
L.

Diversity
c.2160 species
Type Species
Euphorbia serrata
Subgenera
Chamaesyce

Esula
Euphorbia
Rhizanthium
and see below

Synonyms
Chamaesyce

Elaeophorbia
Endadenium
Monadenium
Synadenium
Pedilanthus

Euphorbia is a genus of plants belonging to the family Euphorbiaceae. Consisting of about 2160 species, Euphorbia is one of the most diverse genera in the plant kingdom. Members of the family and genus are sometimes referred to Spurges. 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 ʻakokoTemplate:Verify source

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 bellyTemplate:Verify source. Carolus Linnaeus assigned the name Euphorbia to the entire genus in the physician's honor.[1]

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.

Description

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 pseudanthia called cyathia. The majority of species are monoecious (bearing male and female flowers on the same plant), although some are 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.

Xerophytes and succulents

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.

Toxicity

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 how caustic and irritating to the skin it is. In contact with mucous membranes (eyes, nose, mouth) the latex 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 spurges should be handled 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). A physician should be consulted regarding any inflammation of a mucous membrane. It has been noticed, when cutting large succulent spurges in a greenhouse, that vapours from the latex spread and can cause severe irritation to the eyes and air passages several metres away. Precautions, including sufficient ventilation, are required. Small children and domestic pets should be kept from contact with spurges.

Uses

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.

Systematics and taxonomy

According to recent studies of DNA sequence data[2] 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,[3] Elaeophorbia, Endadenium, Monadenium, Synadenium and Pedilanthus were transferred to Euphorbia. The entire subtribe Euphorbiinae now consists solely of the genus Euphorbia.

Selected species

See List of Euphorbia species for complete list.

Subgenera

File:Euphorbiinae tree.png
Simplified diagram of relations in subtribe Euphorbiinae

The genus Euphorbia is one of the largest and most complex genera of flowering plants and several botanists have made unsuccessful attempts to subdivide the genus into numerous smaller genera. According to the recent phylogenetic studies,[2] 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 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.

  • Esula
  • Rhizanthium
  • Chamaesyce
  • Euphorbia

Footnotes

  1. ↑ Linnaeus (1753): p.450
  2. ↑ 2.0 2.1 Steinmann & Porter (2002), Steinmann (2003), Bruyns et al. (2006)
  3. ↑ Steinmann, van Ee, Berry & Gutiérrez (2007) in Anales del Jardín Botánico de Madrid

References

  • Template:Aut (2006): A new subgeneric classification for Euphorbia (Euphorbiaceae) in southern Africa based on ITS and psbA-trnH sequence data. Taxon 55(2): 397–420. HTML abstract
  • Template:Aut (2005): Succulent Euphorbia plus (CD-ROM). Volker Buddensiek Verlag.
  • Template:Aut (1982): New Succulent Spiny Euphorbias from East Africa
  • Template:Aut (1997): The CITES Checklist of Succulent Euphorbia Taxa (Euphorbiaceae)
  • Template:Aut (1988): Flora of Tropical East Africa, Euphorbiaceae
  • Template:Aut (1753): Species Plantarum (1st ed.)
  • Template:Aut (2001): Succulents in the wild and in cultivation, Part 2 Euphorbia to Juttadinteria (CD-ROM)
  • Template:Aut (2002): Sukkulentenlexikon (Vol. 2: Zweikeimblättrige Pflanzen (Dicotyledonen)). Eugen Ulmer Verlag.
  • Everitt, J.H.; Lonard, R.L., Little, C.R. (2007). Weeds in South Texas and Northern Mexico. Lubbock: Texas Tech University Press.  ISBN 0-89672-614-2
  • Template:Aut (2003): Introduction to the Euphorbiaceae
  • Template:Aut (1983): The Euphorbia Journal Strawberry Press, Mill Valley, California, USA
  • Template:Aut (1994): Succulent Euphorbiaceae of India. Mrs. Meena Singh, A-162 Sector 40, NOIDA, New Delhi, India.
  • Template:Aut (2003): The submersion of Pedilanthus into Euphorbia (Euphorbiaceae). Acta Botanica Mexicana 65: 45-50. PDF fulltext [English with Spanish abstract]
  • Template:Aut (2002): Phylogenetic relationships in Euphorbieae (Euphorbiaceae) based on ITS and ndhF sequence data. Annals of the Missouri Botanical Garden 89(4): 453–490. Template:Doi (HTML abstract, first page image)
  • Template:Aut (1995): Euphorbias - A Gardeners' Guide. Batsford, England.

External links

Template:Commons

ca:Euphorbia de:Wolfsmilch es:Euphorbia eo:Eŭforbio fr:Euphorbe hsb:Mlóčeń it:Euphorbia he:חלבלוב lt:Karpažolė nl:Wolfsmelk ja:トウダイグサ属 pl:Wilczomlecz pt:Euphorbia ru:Молочай (растение) sq:Qumështorja sr:Млечика fi:Tyräkit sv:Törelsläktet zh:大戟屬

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