1. Euphorbiaceae Juss.

    1. This family is accepted.

[NTK]

Esser, H.-J. (2009). Neotropical Euphorbiaceae.

Morphology
Description

Trees, shrubs, climbers or herbs, succulent or not, spiny or not, with white or variously coloured latex or without, usually with extrafloral nectaries. Leaves alternate (rarely subverticillate, opposite or decussate ), petiole short to long (rarely absent), eglandular or glandular , stipules usually present but caducous , rarely intrapetiolar or absent, membranous to scaly , eglandular or glandular , lamina simple , palmately lobed (rarely divided ) or not, rarely peltate , margins entire to variously dentate - serrate ; indumentum of simple , lepidote , dendritic, T-shaped or urticating hairs or absent, venation pinnate to palmate , veinlets variable. Inflorescences unisexual or bisexual , monoecious or dioecious , axillary or terminal , usually elongate racemose, paniculate, thyrsoid, dichasial, more rarely fasciculate -glomerulate or umbel -like or (pistillate), flowers solitary, or grouped into pseudanthia such as cyathia (a female flower surrounded by several staminate ones); bracts small and inconspicuous or larger and conspicuous. Flowers unisexual, small, actinomorphic to rarely zygomorphic , pedicellate to rarely sessile , with 3-5(-8), imbricate to valvate , free to fused sepals or rarely without, petals present or absent. Staminateflowers with (1-)2-20(-90) stamens, filaments free to fused or absent, anthers dorsifixed to basifixed, extrorse to introrse, bilocular , opening with longitudinal slits, disc present or absent, variable, pollen 3(-4)-colporate, porate or inaperturate, tectate-perforate or semitectate, with or without baculae, pistillode absent or present. Pistillate flowers without staminodes, disc present or absent, variously shaped, ovary hypogynous, syncarpous, with (1-)2-3(-20) locules , smooth to spiny , ovule 1 per locule , placentation axile , anatropous, bitegmic, style present or absent, stigmas (1-)2-3(-20), usually elongate, entire , bifid or multifid or rarely bilobed. Fruits septicidally or loculicidally dehiscent schizocarps or (rarely) indehiscent drupaceous . Seeds ellipsoid to ovoid , anatropus, smooth or sculptured, ecarunculate to carunculate, dry, rarely with sarcotesta or aril , endosperm copious, embryo straight, cotyledons usually broad.

Distribution
Distribution in the Neotropics
  • Found throughout the Neotropics, in most vegetation types except for true aquatic plants, but including, e.g. rain forest trees, weeds, and succulents. The family is poorly represented in montane grasslands with only two genera (Dysopsis, Euphorbia), and it does not include epiphytes.
Diagnostic
Distinguishing characters (always present)
  • Flowers small, unisexual.
  • Ovaries hypogynous, syncarpous, with 1 ovule per carpel.
  • Fruits, if dehiscent, with a remaining central columella.
  • Seeds 1 per carpel, anatropous, globose-ellipsoid without sharp edges.
Other important characters
  • Leaves often simple.
  • Stipules present but caducous, small.
  • Leaves often with nectaries.
  • Ovaries and fruits often 3-carpellate.
  • Latex white or yellowish to red (but absent in subfamily Acalyphoideae).
Key differences from similar families

The Euphorbiaceae can be confused with several families with similar fruits and small flowers. The Euphorbiaceae can be distinguished as follows:

  • Phyllanthaceae: ovaries with one ovule per locule, extrafloral nectaries common (in particular on leaves), seeds one per carpel, with sharp edges.
  • Putranjivaceae: plants without glucosinolates, leaf base not oblique, inflorescences usually elongate, fruits usually schizocarpous.
  • Picrodendraceae: leaves mostly not compound, ovaries with one ovule per locule, pollen not 4-8-zonoporate.
  • Peraceae: fruits dehiscing completely (if not indehiscent), seeds not conspicuously shiny black.
  • Violaceae: inflorescenences usually elongate, flowers unisexual, fruits dehiscing completely (if not indehiscent), not notably angular, seeds one per carpel.
Useful tips for generic identification
  • The flowers are very small, and in many cases it is not necessary to study their characters for generic identification. The family is very rich in extrafloral nectaries (on floral bracts, stipules and leaves), and shows a large variation in the type of hairs. The indumentum, the nectaries in particular on the leaves, leaf morphology and venation, inflorescence type, and some characters of fruits and seeds are useful for the identification of genera.
Notable genera and distinguishing features
  • Acalypha - Pantropical with c. 450 species, of which c. 400 are Neotropical; herbs to shrubs with variable hairs but not urticating, leaves simple and serrate-crenate, inflorescences simple, bracts of pistillate flowers accrescent, conspicuous and often serrate to lobed, stigmas laciniate -multifid.
  • Alchornea - Pantropical with c.. 25 Neotropical species; the leaves are often coriaceous and distinctly triplinerved and/or distinctly dentate, the infloresces usually compound; in Neotropical species the ovaries and fruits are always 2-locular with conspicuous long stigmas, in contrast to some similar Neotropical genera that have 3-locular ovaries and fruits (such as Alchorneopsis, Aparisthmium).
  • Astraea Klotzsch - Endemic with c.. 15 species; similar to Croton but usually with lobed leaves and with staminate flowers with a glabrousreceptacle.
  • Caperonia - c. 30 Neotropical species of herbs to small shrubs, characterized by leaves with a typical venation, the straight side veins running directly into the serrate margin of the blade (craspedodromous).
  • Cnidoscolus - Endemic with c. 50 species; similar to Jatropha, but plants with urticating hairs or bristles, leaves biglandular at base, flowers with a petaloidperianth but without separate petals.
  • Croton - A pantropical genus with perhaps 900 Neotropical species; hairs dendritic or lepidote, leaves usually simple with a pair of basalglands, inflorescences mostly simple, staminate flowers with a pubescentreceptacle and with numerous stamens inclinate in bud.
  • Dalechampia - Pantropical but with the majority of its c. 110 species Neotropical; non-stinging, twining herbs to shrubs, leaves very variable and most often palmatilobed, with a very complex pseudanthial inflorescence supported by conspicuous involucral bracts.
  • Dysopsis - Endemic with a single species, being a small herb with suborbicular crenate leaves in montane habitats.
  • Euphorbia - Cosmopolitan and with c. 2250 species one of the largest genera of plants, with less than 400 Neotropical species; herbs to shrubs or succulents, characterized by the unique pseudanthium of much-reduced flowers (cyathium); recently all cyathia-bearing species were united into one single genus (Steinmann & Porter 2002).
  • Hevea - Endemic with c. 15 species (its distribution defining the Amazonian region); hairs simple, leaves 3-foliolate, inflorescences pseudopaniculate, flowers without petals.
  • Jatropha - Pantropical with c. 100 Neotropical species; herbs to trees, sometimes succulent, often with a thick rootstock, hairs simple, leaves variously shaped but often palmately lobed, stipules often conspicuous and multifid, inflorescences dichotomous, corymbiform, flowers with distinct sepalas and petals.
  • Mabea - Endemic with c. 40 species; hairs dendritic and brownish to reddish, staminate flowers pedicellate with numerous (up to 90) stamens each, ovaries and fruits tomentose, pistillate flowers with long styles.
  • Manihot - Endemic with c. 100 species; not urticating, leaves simple to palmately lobed, often pruinose-glaucescent, eglandular but stipellate at base, inflorescences racemose-paniculate, flowers without petals.
  • Microstachys - Pantropical with c. 15 Neotropical species; herbs to small shrubs, hairs simple to dendritic but not urticating, inflorescences elongate and basically bisexual but pistillate and staminate flowers often separated on different nodes, ovaries and fruits usually with six pairs or rows of spines.
  • Plukenetia - Pantropical with most of its 15 species Neotropical; climbing vines to lianas, hairs simple, leaves simple, conspicuously glandular at base, inflorescences leaf-opposed, racemose-paniculate, flowers and fruits 4-merous (the 4-merous flowers distinguish it from several similar genera).
  • Sapium - Endemic with c. 25 woody species; leaves simple with petiolar glands, staminate flowers subsessile with 2 stamens each, seeds with a red aril.
  • Sebastiania - Endemic with c. 20 species; woody plants with simple elongate inflorescences, the staminate flowers subsessile and with 3 stamens and 3 free sepals, the fruits regular with a notably thin wall.
  • Stillingia - Pantropical with the majority of its 27 species Neotropical; similar to Sapium but with more variation in habit (subshrubs to trees or succulents), the petioles eglandular, the fruits with a characteristic woodypersistent cornute base, seeds dry without an aril.
  • Tragia - Pantropical with c. 60 Neotropical species; herbs to subshrubs, often twining, indumentum of simple and urticating hairs, leaves simple and often serrate, inflorescences often leaf-opposed, racemose, staminate flowers with 2-50 stamens. Some smaller similar genera differ in minor floral characters, and the generic limits are not completely solved yet.
General Description
Number of genera

Euphorbiaceae are pantropical and comprise c. 230 genera and c. 5700 species. In the Neotropics they are represented by 82 genera and c. 2550 species:

Acalypha L.Acidocroton Griseb.Acidoton Sw.Actinostemon Mart. ex KlotzschAdelia L.Adenophaedra (Müll.Arg.) Müll.Arg.Alchornea Sw.Alchorneopsis Müll.Arg.Aleurites J.R. & G.Forst.Angostylis Benth.Anomalocalyx DuckeAparisthmium Endl.Argythamnia P.BrowneAstraea KlotzschAstrococcus Benth.Bernardia Houst. ex Mill.Bonania A.Rich.Brasiliocroton P.E.Berry & I. CordeiroCaperonia A.St.-Hil.Caryodendron H.Karst.Chiropetalum A.Juss. Cleidion BlumeCnidoscolus PohlCodiaeum Rumph. ex A.Juss.Colliguaja MolinaConceveiba Aubl.Croton L.Dalechampia Plum. ex L.Dalembertia Baill.Dendrocousinsia Millsp.Dendrothrix EsserDitaxis Vahl ex A.Juss.Ditta Griseb.Dodecastigma DuckeDysopsis Baill.Enriquebeltrania Rzed.Euphorbia L.Gavarretia Baill.Glycydendron DuckeGrimmeodendron Urb.Gymnanthes Sw.Haematostemon (Müll.Arg.) Pax & K.Hoffm.Hevea Aubl.Hippomane L.Hura L.Jatropha L.Lasiocroton Griseb.Leucocroton Griseb.Mabea Aubl.Manihot Mill.Maprounea Aubl.Micrandra Benth.Micrandropsis W.A.RodriguesMicrostachys A.Juss.Nealchornea HuberOmphalea L.Ophellantha Standl.Ophtalmoblapton AllemãoPachystroma Müll.Arg.Pausandra Radlk.Philyra KlotzschPlatygyne P.MercierPleradenophora EsserPlukenetia L.Polyandra LealPseudosenefeldera EsserRhodothyrsus Esser Ricinus L.Romanoa Trevis.Sandwithia Lanj.Sapium Jacq.Sebastiania Spreng.Senefeldera Mart.Senefelderopsis Steyerm.Stillingia Garden ex L.Tetraplandra Baill.Tetrorchidium Poepp. & Endl. Tragia L. Vaupesia R.E.Schult.Vernicia Lour.

Status
  • Seventy-eight of the 82 genera (95%) are native; 60 of these are endemic.
  • Four, originally paleotropical, genera are cultivated with a single species each: Aleurites (candle nut), Codiaeum (garden croton), Ricinus (castor oil), Vernicia (tung oil).
Notes on delimitation
  • The Euphorbiaceae were considered as a morphologically well defined family for a long time, based mostly on their unisexual flowers and the typical schizocarpous fruits. Recent molecular studies resulted in the recognition of several, mostly smaller families (Peraceae, Phyllanthaceae, Picrodendraceae, Putranjivaceae), that are also characterized sufficiently by morphological characters (see below). In this most recent circumscription, Euphorbiaceae are clearly monophyletic.
Literature
Important literature

Govaerts, R., Frodin, D.G. & Radcliffe-Smith, A. 2000. World checklist and bibliography of Euphorbiaceae (with Pandaceae). London: Royal Botanic Gardens, Kew.

Radcliffe-Smith, A. 2001. Genera Euphorbiacearum. London: Royal Botanic Gardens, Kew.

Steinmann, V.W. & Porter, J.M. 2002: Phylogenetic relationships in Euphorbieae (Euphorbiaceae) based on ITS and ndhF sequence data. Ann. Missouri Bot. Gard. 89: 453-490.

Webster, G.L. 1994. Classification of the Euphorbiaceae; Synopsis of the Genera and Suprageneric taxa of Euphorbiaceae. Ann. Missouri Bot. Gard. 81(1): 3-32, 33-144.

Wurdack K.J., Hoffmann, P. & Chase, M.W. 2005. Molecular phylogenetic analysis of uniovulate Euphorbiaceae (Euphorbiaeae sensu stricto) using plastid rbcL and trnL-F DNA sequences. Amer. J. Bot. 92(8): 1397-1420.

[FTEA]

Euphorbiaceae, A. R.-Smith. Flora of Tropical East Africa. 1987

Habit
Dioecious or monoecious often poisonous prostrate, erect or scandent annual, biennial or perennial herbs, shrubs or trees, with the stems succulent or not, spiny or unarmed, sometimes with phylloclades, with or without a milky latex or coloured sap; indumentum 0 or of simple, branched or stellate hairs or peltate scales, the hairs sometimes urticating
Leaves
Leaves usually alternate, sometimes opposite, rarely whorled, occasionally all three, green or scarious and squamiform, commonly petiolate, sometimes sessile, stipulate or exstipulate, simple, lobed or compound, entire or variously toothed, peltate or not, palminerved or penninerved, often with a pair — sometimes with several pairs — of basal glands at or near the petiole-insertion, and/or minutely pellucid-glandular-punctate beneath
Stipules
Stipules free or connate, sometimes spathaceous, membranaceous, capilliform, glandular or spiny, subpersistent to readily caducous or 0
Inflorescences
Inflorescences terminal, axillary, lateral or leaf-opposed, cymose, paniculate, racemose or spicate, or with the flowers aggregated into involucrate pseudanthia, as in the glanduliferous cyathia of the Euphorbieae, which may themselves be aggregated into pseudopleiochasial super-inflorescences, or else with the flowers fasciculate or solitary in the leaf-axils
Flowers
Flowers unisexual, usually actinomorphic and small to minute
Calyx
Calyx in both sexes usually of 3–6-valvate, imbricate or open equal or unequal lobes or free sepals, often dissimilar between the two sexes, rarely the ? calyx spathaceous, sometimes accrescent, minute or 0
Corolla
Corolla in one or both sexes of 3–6 free or rarely united subvalvate or imbricate petals, or petals minute or 0
Nectaries
Disc in the ? flowers of 5–6 or occasionally more free extrastaminal and/or intrastaminal glands, rarely the disc annular or cupular and extrastaminal or lobate and central, or else the disc receptacular, domed and aperturate with the stamens arising through the apertures, or disc 0; in the ? flowers hypogynous, annular and flat or cupular, entire or lobate, rarely of separate glands, or 0
Androecium
Stamens (1–)3–100(–1000), the filaments free or connate into a central column, simple or rarely branched, anthers 2(–4)-thecous, dehiscing longitudinally, rarely by pores, erect or inflexed in bud, with the thecae usually parallel and adnate to the connective throughout, sometimes free at the base, occasionally completely free and erect, divaricate or pendulous, rarely with the thecae superposed or laterally fused to form an annulus
Gynoecium
Ovary superior, sessile or rarely stipitate, 1–4(–20)-locular but most commonly 3-locular; placentation axile, with the ovules solitary or 2 and collateral in each locule and pendulous from its inner angle, anatropous, hemitropous or amphitropous, epitropous, crassinucellate, with a ventral raphe and with the hilar region between the raphe and the epimicropylar obturator, when the latter present; funicle often thickened; styles 1–4(–20), usually 3, free or united, erect or spreading, entire, bifid, multifid or laciniate, with the inner face usually stigmatic throughout and smooth, granulate, papillose or fimbriate and often tinged reddish or purplish
Sterile Parts
Staminodes occasionally present, usually subulate, or 0 Pistillode often present, variously shaped
Fruits
Fruit usually schizocarpic, dehiscing septifragally and septicidally into 1–4(–20) (but usually 3) bivalved cocci leaving a persistent winged or angled columella, the valves then opening ventrally to allow the seeds to escape, or else the fruit loculicidally dehiscent, usually into 3 septate valves, or all three modes of dehiscence present and ± simultaneous, or else the fruit indehiscent, drupaceous or subdrupaceous, with an epicarp, with or without a fleshy mesocarp and with a paleaceous, crustaceous, ligneous or osseous endocarp, 1–3-or more locular
Seeds
Seeds 1–2 per locule, or by abortion solitary in the fruits, attached near or above the middle of the locule, carunculate or not, often myrmecochorous; testa crustaceous to osseous; endosperm usually copious and fleshy, rarely 0; embryo straight, extending for most of the length of the seed; radicle superior; cotyledons usually broad and flat, rarely thick and fleshy or folded
[FZ]

Euphorbiaceae, A. Radcliffe-Smith. Flora Zambesiaca 9:4. 1996

Habit
Prostrate, erect or scandent, annual biennial or perennial, dioecious or monoecious herbs, shrubs or trees, succulent or not, spiny or unarmed, sometimes poisonous, sometimes with phylloclades, with or without a milky latex or coloured sap
Indumentum
Indumentum absent or of simple, branched or stellate hairs or peltate scales, the hairs sometimes urticating
Leaves
Leaves usually alternate, sometimes opposite, rarely whorled, occasionally all three, green or scarious and squamiform, petiolate or sessile, stipulate or exstipulate, simple, lobed or compound, entire or variously toothed, peltate or not, palminerved or penninerved, often with a pair or several pairs of basal glands at or near the petiole insertion, and/or sometimes minutely pellucid-glandular-punctate beneath
Stipules
Stipules free or connate, sometimes spathaceous, membranaceous, capilliform, glandular or spiny, subpersistent, readily caducous or absent
Inflorescences
Inflorescences terminal, or axillary, lateral or leaf-opposed, cymose or paniculate, or racemose or spicate, or with the flowers aggregated into glanduliferous involucrate pseudanthia (cyathia), which may themselves be aggregated into pseudopleiochasial hyperinflorescences, or into involucrate capitula, or else with the flowers fasciculate or solitary, ramiflorous or cauliflorous
Flowers
Flowers unisexual, usually actinomorphic, small to minute
Calyx
Calyx in both sexes usually of 3–6 valvate, imbricate or open, equal or unequal lobes, or of free sepals, often dissimilar as between the two sexes, rarely the female calyx spathaceous, sometimes accrescent, or minute or absent
Corolla
Corolla in one or both sexes of 3–6 free or rarely united subvalvate or imbricate petals, or petals minute or absent
Nectaries
Disk in the male flowers of 5–6 (occasionally more) free extrastaminal and/or interstaminal glands, less often the disk annular or cupular and extrastaminal or lobed, lobulate and intrastaminal with the stamens enfolded by the lobes, or else the disk receptacular, domed and aperturate with the stamens arising through the apertures, or disk absent; in the female flowers hypogynous, annular, flat or cupular, entire or lobed, rarely of separate glands, usually persistent, or absent
Androecium
Stamens (1)3–100(1000), the filaments free or variously connate, simple or rarely branched, anthers erect or inflexed in bud, 2–4-thecous with the thecae usually parallel and adnate to the connective throughout, sometimes free at the base, occasionally completely free and erect, divaricate, horizontal or pendulous, rarely with the thecae superposed or laterally fused to form an annulus, dehiscing by slits longitudinally, obliquely or laterally, less often by pores (not Africa)
Gynoecium
Ovary superior, sessile or rarely stipitate, 1–4(20)-locular but most commonly 3-locular; placentation axile, with the ovules solitary or paired and collateral in each locule and pendulous from its inner angle, anatropous or hemitropous, rarely orthotropous (Panda), crassinucellate, bi-integumental, hilum between the ventral raphe and the epimicropylar obturator, when present; funicle often thickened; styles (1)3(4)(20), free or connate, erect or spreading, entire, bifid, multifid or laciniate, the inner surface usually stigmatic throughout, smooth, granulate, papillose or fimbriate, often reddish- or purplish-tinged
Sterile Parts
Staminodes absent or occasionally present, usually subulate Pistillode (non-functional ovary) often present, variously shaped
Fruits
Fruit smooth, wrinkled, warty, tubercled, horned or winged, rarely inflated, often schizocarpic, dehiscing septifragally and septicidally into 1–4(20) (but usually 3) bivalved cocci leaving a persistent angled or winged columella, the valves then dehiscing loculicidally, or else fruit loculicidally dehiscent into 3 separate valves, or breaking up irregularly, or else indehiscent, drupaceous or subdrupaceous, with a thin epicarp, with or without a fleshy mesocarp and with a 1–3(more)-locular paleaceous, crustaceous, ligneous or osseous endocarp
Seeds
Seeds 1–2 per locule, or by abortion 1 per fruit, carunculate or not, often myrmecochorous; sarcotesta sometimes present; sclerotesta thin, crustaceous to thick, osseous; endosperm copious, fleshy, or absent; embryo straight to curved or folded, extending for most of the length of the seed; radicle superior; cotyledons usually broader than the radicle, flat, rarely thick and fleshy or folded
[FWTA]

Euphorbiaceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:2. 1958

Habit
Trees, shrubs or herbs, occasionally with milky juice
Leaves
Leaves alternate or rarely opposite, simple or digitately compound, sometimes reduced, mostly stipulate
Flowers
Flowers unisexual, mostly monoecious
Calyx
Sepals imbricate or valvate, or in very specialized inflorescences much reduced or absent
Corolla
Petals absent or rarely present and sometimes united
Androecium
Stamens 1–1, 000, free or variously connate; anthers 2–4-celled, erect or inflexed in bud, opening lengthwise, rarely by pores
Sterile Parts
Rudimentary ovary often present in the male flowers
Gynoecium
Ovary mostly 3-celled; styles free or united at the base; ovules solitary or paired, pendulous from the inner angle of the cells
Fruits
Fruit a capsule or drupe
Seeds
Seeds often with a conspicuous caruncle; endosperm copious, fleshy; embryo straight

Images

Euphorbiaceae Juss. appears in other Kew resources:

First published in Gen. Pl. [Jussieu] 384. 1789 [4 Aug 1789] (1789)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385

Sources

Flora Zambesiaca
Flora Zambesiaca
http://creativecommons.org/licenses/by-nc-sa/3.0

Flora of Tropical East Africa
Flora of Tropical East Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Flora of West Tropical Africa
Flora of West Tropical Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2018. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Kew Science Photographs
Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

Neotropikey
Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.
http://creativecommons.org/licenses/by/3.0