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20. Euphorbiaceae

大戟科 da ji ke

Authors: Bingtao Li, Huaxing Qiu, Jin-shuang Ma, Hua Zhu, Michael G. Gilbert, Hans-Joachim (Hajo) Esser, Stefan Dressler, Petra Hoffmann, Lynn J. Gillespie, Maria Vorontsova & Gordon D. McPherson

Euphorbia stracheyi

Credit: Harvard University Herbaria

Trees, shrubs, or herbs, rarely woody or herbaceous lianas, monoecious or dioecious, indumentum of simple, branched, stellate, or gland-tipped hairs, peltate or glandular scales or stinging hairs, latex often present, clear, white, or colored; roots woody, rarely roots tuberous and stems succulent, sometimes spiny. Leaves alternate or opposite, rarely whorled; stipules usually present, often free, sometimes modified into spines or glands, deciduous or persistent; petioles long to short, sometimes with glands at apex or base; leaf blade simple, sometimes palmately lobed, rarely compound, or reduced to scales, margins entire or toothed, sometimes with distinct glands along margin and/or on surface, venation pinnate or palmate. Inflorescences axillary or terminal, flowers in cymes or fascicles, these often arranged along an elongated axis, branched or unbranched, forming a thyrse, in congested heads, or in a flowerlike cyathium with very reduced flowers enclosed within a ± cupular involucre; bracts sometimes petaloid. Flowers unisexual, within same inflorescence or in separate inflorescences, actinomorphic. Sepals (1-)3-6(-8), free or connate into calyx tube, valvate or imbricate, rarely absent (Euphorbia). Petals free, often reduced or absent. Disk present or absent. Male flowers with disk intrastaminal or extrastaminal, entire to dissected. Stamens one to very many, hypogynous; filaments free or connate; anthers 2(-4)-locular, mostly dehiscing longitudinally, rarely transversely or by pores, introrse or extrorse; rudimentary ovary sometimes present. Female flowers rarely with staminodes; ovary superior, (1-)2-5(-20)-locular; placentation axile; ovules 1 or 2 per locule, anatropous or hemitropous; styles free or connate, entire or lobed, or multifid, lobes erect, horizontal or curved; stigma capitate, linear, fimbriate, fan-shaped or pinnatilobate. Fruit typically a capsule elastically dehiscent into 2-valved cocci from a persistent columella, sometimes a berry or drupe. Seeds 1 or 2 per locule; seed coat thin to indurate, sometimes fleshy to form a sarcotesta; caruncle sometimes present; aril sometimes present; endosperm present or absent; embryo straight to curved or folded; cotyledons usually broader than radical. x = 6-14.

Trees, shrubs, or herbs, usually without latex (present in Bischofia); indumentum of simple hairs (branched in Phyllanthus reticulatus), often absent. Leaves alternate, often distichous, sometimes scalelike on main stems; petiole usually short, usually without glands (present in Aporosa); leaf blade simple, margin entire or minutely serrulate (long petioles, 3(-5)-foliolate with toothed margins in Bischofia); venation pinnate, rarely obscurely 3-veined from base. Inflorescences mostly axillary, without visible axis (present in Antidesma, Aporosa, Baccaurea, Bischofia, Richeriella). Male flowers with 2-8 stamens, anthers longitudinally dehiscent (variable in Phyllanthus); female flowers with 2 ovules per locule. Seeds without caruncle, sometimes with fleshy aril or fleshy testa.

Trees to shrubs. Leaf blade leathery, grayish when dry, base often asymmetrical. Ovules 1 per locule; stigmas dilated, peltate or reniform. Fruit a relatively large 1-seeded drupe, usually crowned by persistent flaplike stigmas. Seeds without caruncle.

Plants with or without latex; indumentum of simple, stellate, scalelike, stinging, or glandular hairs, sometimes absent. Leaves alternate or opposite; leaf blade simple or compound, sometimes deeply divided, margin entire or variously toothed, often with sessile glands near junction with petiole and/or along margins; venation pinnate or palmate. Inflorescences basically thyrsoid, very variable, often with well-defined main axis and/or distinct cymes, rarely a sessile axillary fascicle. Ovules 1 per locule of ovary. Seed sometimes carunculate, sometimes arillate.

About 322 genera and 8910 species: widespread throughout the world, primarily in the tropics and subtropics, more poorly represented in temperate regions; 75 genera (one endemic, nine introduced) and 406 species (99 endemic, 27 introduced) in China, nearly 95% of which are found in the S and SW parts of the country.

Fifty-nine genera and over 1700 species: mostly tropical, the greatest diversity in SE Asia; 16 genera and 138 species (41 endemic, four introduced) in China.

Four genera and ca. 210 species: throughout the tropics; two genera and 13 species (three endemic) in China.

Two hundred and eighteen genera and over 5700 species: widespread throughout the world, primarily in the tropics and subtropics, more poorly represented in temperate regions; 54 genera (one endemic, nine introduced) and 255 species (55 endemic, 23 introduced) in China.

The Euphorbiaceae as treated here include the following families that have been proposed for segregation: Androstachydaceae, Antidesmataceae, Bischofiaceae, Hymenocardiaceae, Phyllanthaceae, Pedilanthaceae, Picrodendraceae, Porantheraceae, Putranjivaceae, Ricinocarpaceae, Scepaceae, Stilaginaceae, Trewiaceae, and Uapacaceae. The Pandaceae and Buxaceae, formerly included here, are now well established as separate families.

Molecular data has shown that the traditional concept of Euphorbiaceae includes three major lineages that are relatively distantly related to each other: the Phyllanthoids (genera 1-16 in this account), the Putranjivoids (genera 17 and 18), and the Euphorbioids (genera 19-75).

Many species of Euphorbiaceae are of economic importance, probably most importantly as the main source of rubber (Hevea) but also as sources of medicine; foods, both as a staple starch source (Manihot) and fruits (e.g., Phyllanthus emblica); seed oils (Ricinus, Vernicia); and insecticides.

Li Pingt’ao. 1994. Euphorbiaceae. In: Li Pingt’ao, ed., Fl. Reipubl. Popularis Sin. 44(1): ii-viii, 1-217; Kiu Huashing, Hwang Shumei & Chang Yongtian. 1996. Euphorbiaceae (2). In: Kiu Huashing, ed., Fl. Reipubl. Popularis Sin. 44(2): ii-ix, 1-212; Ma Jinshuang & Tseng Yungchien. 1997. Euphorbiaceae (3). In: Ma Jinshuang, ed., Fl. Reipubl. Popularis Sin. 44(3): ii-vi, 1-150.

The Putranjivoid genera resemble phyllanthoids by their 2-ranked leaves, frequently rather small fasciculate flowers, and ovules 2 per locule. They can be distinguished by their leaf blades, stigmas, and fruit. Also, the leaves contain mustard oils and so frequently taste peppery when fresh, although the taste may take a little time to develop.

Key 1. Phyllanthoid genera

1 Leaves 3-foliolate, margin distinctly serrate; plant with red or reddish juice; styles entire.   16 Bischofia
+ Leaves simple, margin entire or minutely serrulate; plant without red juice; styles usually bifid, sometimes connate (Glochidion)   (2)
2 (1) Inflorescences in spikes, racemes, or pseudoracemes, with visible inflorescence axis; plants dioecious; petals absent   (3)
+ Inflorescences in glomerules or fascicles, inflorescence axis not visible or no longer than 1 cm; plants monoecious or dioecious; petals absent or present   (6)
3 (2) Disk present; ovary and fruit 1- or 3-celled; petioles and leaf margins without glands; stamens longer than sepals   (4)
+ Disk absent; ovary and fruit 2-4-celled; petioles and leaf margins sometimes glandular; stamens shorter to longer than sepals   (5)
4 (3) Anthers U-shaped with an enlarged connective; fruit indehiscent; ovary and fruit 1-celled, often laterally flattened; male disk annular, in distinct parts, or cushion-shaped, enclosing stamens and pistillode, never lobed.   13 Antidesma
+ Anthers with parallel thecae and without an enlarged connective; fruit dehiscent, never flattened; ovary and fruit 3-celled; male disk 5-lobed.   6 Richeriella
5 (3) Leaves evenly distributed along branches, usually distichously arranged; leaf margin undulate to denticulate; petiole apex usually glandular.   14 Aporosa
+ Leaves clustered toward branch tips, usually spirally arranged; leaf margin entire; petiole apex without glands.   15 Baccaurea
6 (2) Flowers with petals (sometimes minute and hidden under disk, rarely absent in Actephila) and disk; stamens usually 5; rudimentary ovary present   (7)
+ Flowers without petals; stamens 2-8, sometimes connate; rudimentary ovary absent or present   (10)
7 (6) Sepals imbricate; petals much shorter than to nearly as long as sepals or absent; disk surrounding ovary base at most; female sepals often enlarged   (8)
+ Sepals valvate (rarely female sepals imbricate); petals much smaller than sepals but always visible between sepals; disk enclosing half or more of ovary in young flowers; female sepals never enlarged   (9)
8 (7) Leaves leathery, rarely papery; disk annular; fruit 13-25 mm in diam., exocarp free from endocarp; seed without endosperm.   1 Actephila
+ Leaves membranous to papery (leathery in L. pachyphyllus); disk 5(or 6)-parted, lobes each deeply 2-lobed in male flowers; fruit 5-8 mm in diam., exocarp adnate to endocarp; mature seed with copious endosperm.   2 Leptopus
9 (7) Ovary and fruit usually 3-celled; fruit woody, breaking up at maturity; female sepals caducous in fruit.   3 Cleistanthus
+ Ovary usually 2-celled; fruit fleshy and indehiscent, 1- or 2-celled; female sepals persistent.   4 Bridelia
10 (6) Flowers without disk (male flowers of Sauropus and Breynia with a whorl of scales inserted adaxially at base of calyx lobes)   (11)
+ Flowers with a prominent, usually fleshy disk   (13)
11 (10) Male calyx of free sepals, without adaxial scales; stamens 3-8; ovary 3-15-celled, styles connate into a terete, conical, clavate, or ovoid structure with a usually lobed or toothed apex; fruits longitudinally grooved.   10 Glochidion
+ Male calyx disk-shaped, cup-shaped, funnel-shaped, or turbinate, entire or shallowly lobed, with whorl of scalelike lobes inserted at base of lobes where discernable; stamens 3; ovary 3-celled, styles 3, free or connate at base only; fruits not longitudinally grooved   (12)
12 (11) Male flowers with anthers widely separated on short arms or angles of flat triangular apex of filament column, not overtopped by connective; female calyx with 2 overlapping whorls of sepals, sometimes thicker in fruit; styles spreading and recurved; fruit dehiscent; leaves drying green to brown.   11 Sauropus
+ Male flowers with anthers closely parallel along sides of filament column, or on underside of triangular head; female calyx lobes fused, turbinate or hemispheric, campanulate, cup-shaped, or rotate, not thickened in fruit; styles erect; fruit indehiscent or tardily or incompletely dehiscent; leaves usually drying blackish adaxially.   12 Breynia
13 (10) Male flowers with prominent pistillode; stamens 4-7, free; female disk annular; branchlets sometimes spine-tipped; leaves often fascicled on short shoots, shoots never resembling pinnate leaves; fruit regularly dehiscent or a white berry.   5 Flueggea
+ Male flowers without pistillode; stamens 2-8, free or connate; female disk annular or in distinct parts; branchlets never spine-tipped; leafy branches often resembling pinnate leaves ("phyllanthoid branching"); fruit regularly or irregularly dehiscent, if fleshy and indehiscent, fruit a green to yellow drupe and shoots clearly resembling pinnate leaves or fruit a purplish berry   (14)
14 (13) Dioecious; sepals and stamens 4; disk adnate to receptacle; stamens free; ovary 3-celled; fruit irregularly fragmenting, with brittle, papery endocarp; seeds with thin, fleshy, blue or purplish testa.   7 Margaritaria
+ Monoecious (rarely dioecious); sepals and stamens 2-6; disk not adnate to receptacle; stamens free or connate; fruit dehiscing regularly, with woody endocarp or indehiscent and fleshy; seed coat not fleshy, not blue or purplish   (15)
15 (14) Sepal apex never caudate-acuminate; disk annular to cup-shaped or if of separate glands then these ± round; anther connectives not protruding; capsule to 7 mm or fruit fleshy.   8 Phyllanthus
+ Sepal apex distinctly caudate-acuminate; disk glands linear; anther connectives produced into subulate appendage; fruit usually larger, (5-)8-15 mm, never fleshy.   9 Phyllanthodendron

List of Keys

  • List of lower taxa


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