Euphorbiaceae of Malesia

Key to the Families and Genera of Euphorbiaceae and allied families

 

Welzen, P.C.  van. 2020. Key to the families and genera of Malesian Euphorbiacea in the wide sense. Blumea 65: 53–60.

 

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Key to the Euphorbiaceous Families

Key to the Genera of Malesiana Euphorbiaceae (s.str.)

Key to the Genera of Malesian Pandaceae

Key to the Genera of Malesian Peraceae

Key to the Genera of Malesian Phyllanthaceae

Key to the Genera of Malesian Picrodendraceae

Putranjivaceae

 

Genus names without a link have not been revised yet.

 

Key to the Euphorbiaceous Families

 

1a.

Ovary with a single ovule per locule

2

1b.

Ovary with two ovules per locule

4

2a.

Fruits drupes. Flowers of both sexes with petals

Pandaceae

2b.

Fruits capsules, sometimes drupes or berries, then flowers of both sexes lacking petals

3

3a.

 Herbs, shrubs, lianas, trees, mono- or dioecious. Flowers in cauliflorous, ramiflorous, axillary, or terminal inflorescences

Euphorbiaceae

3b.

Shrubs to trees, dioecious. Flowers in axillary fascicles

Peraceae

4a.

Leaves opposite, without candelabriform (Terminalia-)branching pattern

Picrodendraceae

4b.

Leaves spirally arranged to distichous (to opposite, then candelabriform (Terminalia-)branching pattern present (groups of leaves with short nodes in between, interspersed by long leafless internodes)

5

5a.

Stamens free, inserted around a broadly lobed or folded disc; stigmas broad, flat, fan- to almost kidney-shaped. Base of leaf blade asymmetric

Putranjivaceae

5b.

Stamens free to united, outside the disc or among the disc lobes; stigmas slender and linear to sometimes spade- or petal-like (then base of leaf blade symmetric)

6

6a.

Stamens 28–68; filaments united. Stigmas petal-like

Picrodendraceae

6b.

Stamens less than 20, filaments free to united. Stigmas slender and linear to spade-like, not petal-like

7

7a.

Stigmas spade-like. Sepals 4. Stamens 10–14

Picrodendraceae

7b.

Stigmas slender and linear. Sepals 4 or more, but if 4 then stamens < 6

Phyllanthaceae

 

 

Key to the Genera of Malesiana Euphorbiaceae (s.str.)

 

1a.

Leaves 3–7-foliolate, leaflets completely free

2

1b.

Leaves simple, at most palmatifid and lobes at least basally united (3–9 nerves)

3

2a.

Leaves 3–5(–7)-foliolate; leaflets abaxially with hair tuft domatia. Sepals free. Petals present. Stigma 1–1.2 mm long. ― New Guinea

Annesijoa

2b.

Leaves 3-foliolate; leaflets abaxially without domatia. Sepals united. Petals absent. Stigmas 0.2–0.8 mm long. ― Cultivated, escaped/abandoned, mainly W Malesia

Hevea

3a.

Flowers in a cyathium (a small cup-like and glandular involucre, the glands sometimes with petal-like appendages, enclosing several staminate flowers consisting of one stamen and one pistillate flower consisting of a single ovary). Cyathia surrounded by calyx-like, sometimes petal-like bracts, or sometimes even upper leaves red-coloured. Plants creeping to erect herbs, small shrubs, or often succulent and even cactus-like. Rich in white latex

Euphorbia

3b.

Flowers never in cyathia, usually separate, sometimes in dense heads, but then heads not surrounded by calyx-like or coloured bracts. Plants herbs, shrubs, climbers/lianas or trees. Succulent stem usually absent (Falconeria somewhat exceptional), thorn-shaped stipules absent. Latex absent or present, then red or white

4

4a.

Plant deciduous, flowering and fruiting while leafless; latex white. Branchlets thick, soft, spongy, shrivelled when dry

Falconeria

4b.

Plant deciduous or not, flowering and fruiting while (just) in leaf; latex absent to variably coloured (watery, white, red). Branchlets not spongy

5

5a.

Lianas or plants straggling, stellate or lepidote hairs or stinging hairs present in at least one part

6

5b.

(Prostrate) herbs, shrubs or trees, stellate or dendritic hairs present or not, stinging hairs generally absent (present in Croton hirtus, a herb, and some Macaranga species, trees)

13

6a.

Stellate or lepidote hairs present. Either extrafloral nectaries present on upper surface of leaf near base or glands abaxially between petiole and leaf blade

7

6b.

Stinging hairs present. Extrafloral nectaries absent, glands absent at lower surface, can be present on upper surface between petiole and leaf blade

8

7a.

Extrafloral nectaries as a pair of glands present abaxially between blade and petiole. Inflorescences bisexual (pistillate basally, staminate apically, latter part breaking off in fruit). Petals present only in staminate flowers. Ovaries and fruits 3-locular

Croton

7b.

Extrafloral nectaries as glandular areas, basally at upper surface leaf blade; no glands at lower surface between petiole and blade. Inflorescences unisexual. Petals absent. Ovaries and fruits 2-locular

Mallotus

8a.

Inflorescences capitate, enveloped by 2 large membranous bracts. Leaves pinnatisect

Dalechampia

8b.

Inflorescences spikes, panicles or cymes, sometimes with large bracts at end of inflorescence (not enveloping inflorescence). Leaves not dissected

9

9a.

Leaves coriaceous. Inflorescences with floral bracts > 2 cm long at end of inflorescence. Stamens connate

Omphalea

9b.

Leaves papery. Inflorescences with floral bracts < 1 cm long. Stamens free

10

10a.

Leaf base with 2 raised glands on upper surface. Stamens 8–13. Capsules 4-locular, winged or horned

Plukenetia

10b.

Leaf base without apically raised glands on upper surface. Stamens 2 or 3. Capsules 3-locular, without wings or horns

11

11a.

Inflorescences terminal, but sometimes on leafless sidebranches and appearing laterally. Staminate calyx 4- or 5-lobed; stamens 2, subsessile, filaments slender, connective not thickened, nor elongated above thecae. Pistillate calyx lobes c. 2 mm long

Pachystylidium

11b.

Inflorescences axillary or leaf-opposed. Staminate calyx 3-lobed; stamens 3, filaments thickened, connective thick, appendaged above thecae. Pistillate calyx lobes > 2 mm long, especially in fruit

12

12a.

Leaf blades ovate and basally cordate to obovate with a narrow cordate base, widest above leaf insertion. Pistillate calyx with 3 lobes, < 1 cm long in fruit; styles free, stigmas papillate, persistent

Cnesmone

12b.

Leaf blades broadly cordate, widest at leaf insertion. Pistillate calyx with 6 lobes, > 1 cm long in fruit; styles connate into an obconic structure, stigmas not papillate, nor persistent

Megistostigma

13a.

Leaves palmatifid for at least the upper third of the leaf blade; basal nerves palmate, supporting lobes

14

13b.

Leaf blades not palmate or palmatifid for not more than the upper third of the leaf blade; nerves usually pinnate (to palmate)

19

14a.

Leaf margins entire or serrate (sometimes only vein endings extruding); if entire then leaves peltate and flowers without petals

15

14b.

Leaf margins entire or with lobe-like serration; leaves not peltate (except Jatropha podagrica peltate, with petals)

16

15a.

Leaves with 2, 3 or 5 lobes. Stipules beside petiole base, not united and not encircling stem or united and encircling stem. Leaf blades underneath with glandular scale hairs. Stamens 1‒60, not branching

Macaranga

15b.

Leaves with 7 or 9 lobes. Stipules united, opposite to leaves, encircling stem. Leaf blades underneath lacking glandular scale hairs. Stamens > 100, arising from dichotomously splitting androphores

Ricinus

16a.

Insertion of petiole with base of leaf blade with 1 or 2 raised glands

17

16b.

Insertion of petiole with base of leaf blade without glands

18

17a.

Leaf blades 5- or 7-lobed, margin laxly serrate with almost lobe-like serrations. Petals absent (sepals like petals)

Cnidoscolus

17b.

Leaf blades 3- or 5-lobed, margin entire. Petals > 1 cm long

Vernicia

18a.

Leaves divided to 2/3 only, either peltate (> 2 mm) and without glandular hairs or basally attached and with glandular hairs. Petals (red or greenish white) present

Jatropha

18b.

Leaves almost completely divided, basally attached or slightly (2 mm) peltate, without glandular hairs. Petals absent

Manihot

19a.

All inflorescences/infructescences opposite to leaf, or seemingly opposite but then in axil of stipule-like leaf (often caducous) and up to 2 mm broad (several Mallotus species have very dimorph opposite leaves, of which the reduced one bears the inflorescence axillary, these all 4 or more mm wide)

20

19b.

Inflorescences/infructescences in axils of (fallen) leaves to rami- or cauliflorous

23

20a.

Woody herbs to subshrubs. Leaf blade margins with small, dense teeth. Ovaries and fruits with 2 longitudinal rows of small spines per lobe

Microstachys

20b.

Shrubs to trees. Leaf blade margins without dense teeth. Ovaries and fruits smooth or with randomly dispersed (long) spines

21

21a.

Inflorescences up to 1 cm long, opposite to alternate leaves, 2 stipules per node. Ovaries and fruits smooth. Staminate sepals 5, stamens up to 25(–60)

Suregada

21b.

Inflorescences 2‒2.6 cm long or up to 12 cm long, in axil of stipuliform leaf (leaves opposite with 4 stipules in between per node). Ovaries and fruits echinate. Staminate sepals 3 or 4, stamens c. 60 or c. 98

22

22a.

Inflorescences up to 12 cm long. General indument of simple (or glandular hairs). Upper leaf blade without extrafloral nectaries, lower surface without glandular scale hairs

Hancea

22b.

Inflorescences 2‒2.6 cm long. General indument of simple and stellate hairs. Upper leaf blade with 2–4 basal extrafloral nectaries, lower surface usually with glandular scale hairs

Mallotus

23a.

Leaves (sub)opposite, in (pseudo)whorls or in groups of three

24

23b.

Leaves alternate. Check especially mature leaves along thicker branches, leaves at base and especially at end of branches sometimes seemingly opposite

33

24a.

Leaves opposite

25

24b.

Leaves in (pseudo)whorls or in groups of three

30

25a.

Lower surface of leaves and/or inflorescences with stellate hairs and/or glandular scales (microscope or hand lens!, sometimes only along the basal margin!; check especially young parts). Leaf blades often peltate

Mallotus

25b.

Leaves and inflorescences glabrous or with simple hairs. Leaf blades not peltate

26

26a.

Stipules 2 per node, interpetiolar

27

26b.

Stipules 2 per leaf, 4 per node

29

27a.

Stipules large, ovate with cordate base, 8–45 by 5–36 mm. Inflorescence either staminate or pistillate, up to 22 cm long, not condensed

Moultonianthus

27b.

Stipules small, triangular, 3.2–13 by 1–3.3 mm. Inflorescences either staminate or pistillate and then condensed, up to 5 or 3 cm long, respectively, or inflorescences per node with several staminate and a single pistillate flower, up to 34 cm long

28

28a.

Staminate inflorescences very condensed, up to 3 cm long; pistillate inflorescences consisting of a single flower

Erismanthus

28b.

Inflorescences with several staminate flowers per node and a single pistillate flower, up to 34 cm long

Syndiophyllum

29a.

Latex white.Plants completely glabrous (check young parts). Petiole 4 or more mm long. Stamens 3. Sepals 3. Ovaries and fruits smooth

Excoecaria

29b.

Latex absent. Plants partly with some hairs. Petiole 1‒4 mm long. Stamens > 100 in 4–7 dichotomously branching groups. Sepals 5. Ovaries and fruits echinate

Lasiococca

30a.

Hairs stellate or lepidote (can be very small), sometimes next to simple ones. Stipules present (often early caducous)

31

30b.

Hairs only simple, or very small ones lepidote, but then stipules absent

32

31a.

Hairs stellate. Leaves glabrous beneath, main veins perpendicular to midrib. Stamens 25‒30 on a columnar receptacle, not inflexed in bud. Ovaries/fruits 2-locular, stigmas apically twice bilobed

Borneodendron

31b.

Hairs stellate or lepidote. Leaves densely hairy underneath (leaf blade often not visible), veins ascending. Stamens 10‒20, free, inflexed in bud. Ovaries/fruits 3-locular, stigmas apically once split

Croton

32a.

Petioles 4‒185 mm long, apically but more so basally pulvinate. Leaf blades ovate to elliptic to obovate, 4.6‒51 by 2‒26.5 cm. Stamens free, 31‒40. Ovaries and fruits with at most somewhat knobbly surface. Seeds surrounded by a sarcotesta

Blumeodendron

32b.

Petioles 1‒4 mm long, completely pulvinate. Leaf blades obovate, 8‒20 by 2.6‒5.7 cm. Stamens in 4‒7 groups, splitting dichotomously to > 100 anthers. Ovaries and fruits echinate. Seeds without any fleshy layer or caruncle

Lasiococca

33a.

Stipules absent (no scars, but sometimes bud scales may resemble stipules) or very minute, leaving no obvious scar

34

33b.

Stipules present, 2 or united into 1, often early caducous, leaving sometimes small scars at both sides of petiole

42

34a.

Petals present in staminate and pistillate flowers, velutinous on both sides. Stamens connate into an androphore. Fruits drupaceous. ― New Guinea

Fontainea

34b.

Petals absent or present in both sexes or only the staminate flowers, if present glabrous. Stamens free (sometimes adnate when young, but no androphore). Fruits capsular. ― Malesia

35

35a.

Latex abundant, white. Fruits drupes. Staminate calyx cupshaped, 2-lobed, stamens enclosed in calyx. Petals and discs absent. Ovaries 3‒21-locular

Pimelodendron

35b.

Latex absent or inconspicuous, not white. Fruits capsules. Staminate sepals 3‒6, but irregularly splitting in 2 in Botryophora, stamens usually exserted from sepals. Petals absent or present, disc always present. Ovaries 1‒5-locular

36

36a.

Staminate calyx irregularly dehiscing into 2 parts; stamens with sturdy filament with on top an umbrella-shaped connective with 4 equal thecae hanging from its toothed edge. Pistillate sepals 3 or 4, occluded by big disc. Fruits 3- (or 4-) cornered, ovoid, glabrous

Botryophora

36b.

Staminate sepals 3‒6; stamens normal in appearance with apically 2 thecae, or 4 thecae on one side of a triangular connective, inner pair smaller. Pistillate sepals 3‒6, wellvisible (disc inside). Fruits not cornered, but sometimes grooved, ribbed or spiny but then densely hairy, ovoid to usually subglobose or somewhat lobed

37

37a.

Fruits densely hairy, sometimes grooved or with soft spines. Connectives triangular, with on one side 2 pairs of thecae, of which inner smaller; among stamens disc glands with long apical hairs. Pistillate flowers occasionally with staminodes; disc densely hairy

Ptychopyxis

37b.

Fruits glabrous to somewhat hairy and glabrescent, smooth or somewhat knobbly. Connectives narrow or broad (not triangular) with 2 thecae along it; disc glands extra-staminal or among stamens, but always glabrous. Pistillate flowers without staminodes; disc glabrous

38

38a.

Stipules present as bud-like enations. Leaf blades sometimes (basally) lobed, with extrafloral nectaries along margin abaxially, basal ones larger. Stamens with thecae almost confluent on top of connective. Fruit columella, after dehiscence, with strand-like remnants of sutures basally

Baliospermum

38b.

Stipules absent. Leaf blades not lobed, with or without extrafloral nectaries adaxially. Stamens with thecae along connective. Fruit columella basally without extensions

39

39a.

Fruits 2‒6 cm wide by 2‒4.6 cm high, wall 1‒7 mm thick. Staminate disc glands among stamens, clearly separate or giving a ruminate impression of convex receptacle. Leaf blades with 2 extrafloral nectaries (small) adaxially near base and often additional, even smaller ones along midrib and margin

Blumeodendron

39b.

Fruits 1‒1.4 cm wide by 0.8‒1 cm high, wall at most 1 mm thick. Staminate disc glands extra-staminal. Leaf blades without extrafloral nectaries

40

40a.

Stipules absent or otherwise minute, leaving no obvious scar. When cultivated leaf blades variegated or multi-coloured, then often linear or with side lobes or a detached apex, wild forms with long obovate blades to 30 cm long. Stamens 15‒100, connectives broad with on top 2 touching thecae

Codiaeum

40b.

Stipules absent. Leaf blades not variegated, not lobed and no detached apex, up to 22 cm long. Stamens 14‒50, connectives slender with thecae alongside it 

41

41a.

Flowers in umbellate unbranched thyrses (raceme-like), all flowers branching off from same node in the inflorescence, sometimes one or two flowers branching off from a lower node. Pistillate sepals without long glandular fimbriae along margin, not or slightly accrescent in fruit to 2.8 by 1.3 mm. Fruits slightly hairy or glabrous; seeds with or without caruncle. Leaf blades never panduriform

Blachia

41b.

Flowers in terminal unbranched thyrses (raceme-like), with flowers at various nodes. Pistillate sepals accrescent in fruit to 15 by 10 mm, with long glandular fimbriae along margin. Fruits glabrous; seeds carunculate. Leaf blades often panduriform 

Strophioblachia

42a.

Leaves and/or inflorescences with stellate hairs, lepidote hairs, glandular scales and/or scale hairs (microscope or hand lens!, sometimes only on lower surface of leaf blades)

43

42b.

Leaves and/or inflorescences glabrous or with simple hairs only

65

43a.

Leaf blades willow-like (oblong, very narrow, 0.5‒2.5 cm wide, 5‒14 times longer than wide), lower surface with scale hairs, margin (indistinctly) serrate with an abaxial gland in each tooth. Stamens united into a thick androphore from which branches split off that split several times dichotomously. ― Shrubs along and especially in floating rivers

Homonoia

43b.

Leaf blades usually not willow-like, usually broader and less than 5 times as long as wide, lower surface without or with scale hairs (then glandular), margins variable, sometimes with glands in teeth. Stamens not bifurcating dichotomously

44

44a.

Connection or near insertion petiole-leaf blade with glands or extrafloral nectary areas (round, flat or slightly hollow, generally black round/elliptic areas in dry leaves) on upper or lower surface (check various leaves)

45

44b.

Connection or near insertion petiole-leaf blade no glands or extrafloral nectary areas

60

45a.

Glands or extrafloral nectary areas near petiole insertion on lower leaf blade surface

46

45b.

Glands or extrafloral nectary areas near petiole insertion on upper leaf blade surface

50

46a.

Extrafloral nectary areas basally present. Staminate flowers in dense glomerules per inflorescence node

47

46b.

(Slightly) raised to stipitate glands basally present. Staminate flowers in loose groups per inflorescence node

48

47a.

Older stipules with an entire margin. Fruits echinate. Stamens 3‒5 on a short narrow androphore, filaments threadlike; pistillode small. Pistillate sepals not accrescent in fruit; stigmas apically not splitting or only splitting once

Cephalomappa

47b.

Especially older stipules or all with an erose to pectinate margin (lobed). Fruits smooth. Stamens 4‒8 circular on a broad androphore, filaments often sulcate (thread-like in K. laevigatum); pistillode absent to small. Pistillate sepals often accrescent in fruit; stigmas several times bifid to multifid

Koilodepas

48a.

Inflorescencesonlyonesex.Fruitsdrupes (indehiscent).Leaf blades peltate or not. Branches hollow or solid. Petals absent. Stamens united into an androphore, thecae separate, spreading out in horizontal plane

Endospermum

48b.

Inflorescences basally pistillate, apically staminate (this part breaking off in fruit), sometimes unisexual (pistillate). Fruits dehiscing capsules. Leaf blades not peltate. Branches solid. Petals present (at least in staminate flowers). Stamens free or united into an androphore and then thecae united, parallel to androphore

49

49a.

Stamens united into an androphore, straight in bud; anthers 4-thecate. Indumentum dense, stellate. Leaf blade not to usually distinctly 3-lobed. Pistillate flowers with petals and disc, short gynophore underneath ovary

Chrozophora

49b.

Stamens free, inflexed in bud; anthers 2-thecate. Indumentum sparse to dense, stellate to lepidote. Leaf blade not lobed. Pistillate flowers with or without petals, disc present, gynophore absent

Croton

50a.

Leaf blade basally with extrafloral nectary areas (black areas when leaves dry), lower surface usually with glandular disc hairs

51

50b.

Leaf blade basally with (elevated) glands, lower surface without glandular disc hairs

52

51a.

Stamens 1‒3, anthers 3-thecate. Hairs simple. Stem hollow. Inflorescences branched, axillary. Fruit with a glandular patch per locule

Macaranga

51b.

Stamens 15‒130, anthers 2-thecate. Stellate hairs present (sometimes few) on lower leaf surface and/or inflorescences (microscope or hand lens!). Stems solid. Inflorescences not-branched to branched, mainly terminal. Fruits without glandular patches

Mallotus

52a.

Leaf blade margin (indistinctly) dentate/serrate (sometimes only apically), observe with hand lens, especially in Trigonostemon balgooyi difficult to see (plant long hairy)

53

52b.

Leaf blade margin entire

56

53a.

Leaf blade sometimes 3-lobed, base with a group of protruding glands. Inflorescences up to 54 cm long. Petals lacking. Ovary 2- or 3-locular. Stamens 200‒250; connectives abaxially with a gland

Melanolepis

53b.

Leaf blade not lobed, base with 2 glands. Inflorescences up to 40 cm long. Petals absent (ovary 2-locular) or present (ovary 3-locular). Stamens 5‒30; connectives without an abaxial gland (sometimes extending apical cells on connective with purple droplets)

54

54a.

Petals absent. Ovaries 2-locular. Staminate flowers with 5‒9 free stamens and a pistillode. Fruits grey hairy, 1.7‒4.1 cm high. Seeds with a thin red aril

Neoscortechinia

54b.

Petals present. Ovaries 3-locular. Staminate flowers either with 5 united stamens on top of an androphore or 10‒30 stamens of which the outer free and inner united; pistillode absent. Fruits with sparse hairs, brown when mature, up to 2.1 cm high. Seeds naked, without aril/sarcotesta or caruncle 

55

55a.

Trees up to 20 m tall, exuding a red sap. Petals white. Inflorescences 20‒40 cm long. Stamens 10‒30, of which the outer free and inner united. Indumentum of hairs of one length

Paracroton

55b.

Shrubs or small trees, up to 3 m tall, without sap. Petals deep purple. Inflorescences up to 9 cm long. Stamens 5, united on top of an androphore. Indumentum of long and short hairs

Trigonostemon

56a.

Dendritic hairs sometimes present in area of terminal bud (next to stellate and simple hairs). Inflorescence with basally 2 large subopposite bracts of unequal size (3.7‒10.7 by 1.9–5 cm), caducous. Inflorescences cymose. ― N Moluccas (Halmahera)

Weda

56b.

Only simple and/or stellate hairs present. Inflorescences without large basal bracts. Inflorescence (thyrsoid) racemes to panicles

57

57a.

Stamens 5‒10, in a single whorl, free, folded in bud. Petals absent. Pistillate calyx usually with epicalyx (basal small triangular elements), sepals dark red, enlarging in fruit to 5 cm long. Fruits up to 2 cm high

Epiprinus

57b.

Stamens 7‒10 (united in 2 whorls) or 17 to many, in various whorls, especially inner ones united, straight in bud. Petals present. Pistillate calyx usually green, lacking epicalyx, not enlarging in fruit. Fruits either unknown (Alphandia) but probably not big, or 3.5‒6.5 cm high

58

58a.

Leaves elliptic to slightly obovate, not lobed, blade 5.7–18 cm long, pinnately veined.Anthers geniculate on abaxially thickened connective, thecae on front of connective. Fruits probably less than 2 cm high

Alphandia

58b.

Leaves (except in cultivated plants) ovate, often 3- or 5- lobed, blade 4‒40 cm long, basally 3- or 5-veined.Anthers straight, connective not thickened, with thecae alongside. Fruits 3.5‒6.5 cm high

59

59a.

Stellate hairs all over. Leaf blades often 3- or 5-lobed. Stamens 17‒32, in 4 whorls. Pistillate flowers with 5 distinct disc glands. Seeds marbled

Aleurites

59b.

Stellate hairs only on lower leaf blade surface. Leaf blades not lobed. Stamens 7‒10 in 2 whorls. Pistillate flowers with disc glands as minute triangular protuberances. Seeds not marbled

Reutealis

60a.

Leaves white underneath (when dry), coarsely double toothed (to subentire). Inflorescences bisexual with basally at most a few solitary pistillate flowers and staminate flowers in a dense apical head. Stamens 4. Stigmas apically twice divided

Cladogynos

60b.

Leaves various coloured underneath when dry, some whitish, but then inflorescences unisexual, margin entire to dentate/serrate. Inflorescences uni- or bisexual(then basally pistillate flowers), but staminate flowers never in a dense apical head. Stamens 5‒130. Stigmas entire or apically split once

61

61a.

Plants exuding red sap. Petals present in staminate and pistillate flowers. Stamens 10‒30, of which the outer free and inner united

Paracroton

61b.

Plants without obvious sap. Petals only in staminate flowers or absent in both sexes. Stamens 5‒10, c. 75 or 110‒130, free, on receptacle or a torus

62

62a.

Leaf blades (sub)glabrous to somewhat hairy below, not peltate. Staminate flowers with 5‒10 stamens and a pistillode. Plants not spiny

63

62b.

Leaf blades densely hairy underneath, base often peltate. Staminate flowers with 75 or more stamens, no pistillode. Plants spiny or not 

64

63a.

Leaf blades 5.6‒32.5 cm long, margin shallowly (to deeply) laxly dentate to crenate, lower surface subglabrous to slightly sericeous to subhirsute. Ovaries and fruits 3- (or 4-) locular

Cheilosa

63b.

Leaf blades 2.3‒17 cm long, margin usually entire to in upper 2/3 irregularly crenulate to sometimes dentate, lower surface subglabrous. Ovaries and fruits 2-locular

Neoscortechinia

64a.

Plants often spiny. Leaf blades 2.8‒12 cm long, with a palmate venation.Stamens 110‒130, on convex, stellately hairy receptacle. Disc present in pistillate flowers. Fruits 1‒1.4 by 0.5‒0.8 cm

Doryxylon

64b.

Plants not spiny. Leaf blades 6.8‒37 cm long, pinnately veined. Stamens c. 75, inserted on a torus. Disc absent in both sexes. Fruits 2.1‒3.6 by 1.4‒3 cm

Sumbaviopsis

65a.

Insertion between petiole and leaf blade with raised glands on upper or lower surface or lateral on petiole or with stipellae (not glandular, extrafloral nectary areas or glands in basal leaf margin; check various leaves, some leaves may lack the glands)

66

65b.

Insertion between petiole and leaf blade without raised glands (can be glands nearby in leaf margin, e.g., Excoecaria agallocha)

80

66a.

Stipules large (5‒120 mm long), with distinct parallel venation, enclosing buds of leaves and inflorescences, only on young shoots. Raised glands at insertion always abaxially (additionally also often adaxially). Stigmas usually with a gland underneath

Homalanthus

66b.

Stipules generally small (0.3‒45 mm long), generally without distinct venation, caducous to persistent. Raised glands at insertion only adaxially (upper surface) or lateral on petiole. Stigmas without gland underneath

67

67a.

Margin crenate, dentate, serrate (check carefully, especially with young leaves, older leaves may seem entire)

68

67b.

Margin entire

76

68a.

Petals present. Bracts without glands

69

68b.

Petals absent. Bracts with or without basal glands

70

69a.

Petals white. Stamens 20‒41. Fruits 1.9‒2.8 cm wide

Ostodes

69b.

Petals variously coloured (including white). Stamens 3 or 5. Fruits up to 1.5 cm diam

Trigonostemon

70a.

Staminate flowers in dense catkins on long pedicel, staminate flowers consisting of three layers of 10 or more stamens along an androphore. Pistillate flowers single per node/inflorescence, sepals completely connate, enclosing ovary, style long, stigmas 5‒20-locular, united, umbrellalike, lobed. Fruits c. 8 cm wide

Hura

70b.

Staminate flowers generally in loose thyrsoid racemes to panicles, in groups per node, numbers of stamens variable, 2–many, free. Pistillate flowers different, generally several per inflorescence, 2‒4-locular, generally with a short style and free stigmas. Fruits < 4 cm wide

71

71a.

Stipellae or glands present at petiole insertion. Leaf blades ovate (shrubs to small trees). Stamens 6‒8, inserted on a ring-like collar of receptacle, thecae parallel with connective

Alchornea

71b.

Glands present at petiole insertion. Leaf blades (ovate to) orbicular to elliptic to obovate, often herbs when ovate. Stamens 2, 3, 4, 8, 18‒120, if 3, 4 or 8 then not inserted on a ring-like collar and thecae separate on top of connective or the thecae vermiform

72

72a.

Stamens 2. Bracts with 2 big glands. Plants glabrous

73

72b.

Stamens 3‒120. Bracts lacking glands. Plants with hairs in various places

74

73a.

Twigs not succulent. Stipules 1.5‒2.2 mm long, tip acute, entire. Leaf blades apically acute. Fruit columella without basal thickened, woody, (2- or) 3-lobed part. Seeds covered by a red aril, without caruncle

Sapium

73b.

Twigs succulent. Stipules: blade 0.8‒1.5 mm long, tip up to 2 mm long, often divided into several ciliae. Leaf blades apically acute to rounded to retuse, below often with marginal extrafloral nectaries on lower surface. Fruit columella with a basal thickened, woody, (2- or) 3-lobed obtriangular part. Seeds not arillate, with apical caruncle 

Stillingia

74a.

Stamens 8, anthers 2-thecate, vermiform. Allomorphic flowers sometimes present. Pistillate flowers subtended by enlarged bracts

Acalypha

74b.

Stamens 3‒120, anthers not vermiform, either 2- or 4- thecate.Allomorphic flowers absent. Pistillate flowers subtended by normal, non-enlarged bracts

75

75a.

Stamens 40‒120, anthers 4-thecate, consisting of 2 pairs or 2 thecae above each other, along connective, connective with apical appendage. Stigmas 3‒30 mm long, apically deeply divided

Cleidion

75b.

Stamens 3‒66, anthers 2-thecate, thecae separate, basally attached to connective, connective without apical appendage. Pistillate flowers only known of Micrococca mercurialis: with strap-like disc glands and stigmas < 1 mm long, apically undivided

Micrococca

76a.

Flowers without petals, either inflorescences dichasial or thyrsoid racemes with staminate bracts with 2 glands

77

76b.

Flowers with petals. Inflorescences thyrsoid racemes to panicles; bracts glandless

78

77a.

Inflorescences dichasial, bisexual. Leaf blades with lowermost pair of veins equal to others, not forming basal leaf margin. Staminate bracts without glands; staminate flowers with 10‒22 stamens. Pistillate flowers with many staminodes, stigmas short, split, almost knob-like. Seeds shed immediately at dehiscence, without sarcotesta

Elateriospermum

77b.

 Inflorescences racemose thyrses. Leaf blades with lowermost pair of veins originating from the very leaf base and forming the basal leaf margin (at different angle with midrib than other veins). Staminate bracts with a basal pair of glands; staminate flowers with 2 or 3 stamens. Pistillate flowers without staminodes, stigmas short, apically not split. Seeds remaining attached to columella for considerable time after dehiscence, with pale to whitish sarcotesta

Triadica

78a.

Petals variously coloured, including white. Stamens 3 or 5. Stigmas 3 (bifid at apex). Fruits less than 2 cm high

Trigonostemon

78b.

Petals white. Stamens 7‒14. Stigmas 3 and fruits 4‒6 cm high or stigmas 6 and fruits unknown (all stigmas apically bifid)

79

79a.

Blades elliptic, not lobed. Stamens 8, 5 in outer whorl, 3 in inner whorl, anthers shortly sagittate at the base; pistillode minute. Pistillate flowers with annular disc; stigmas 6

Loerzingia

79b.

Blades ovate, not to shallowly or moderately 3- or 5-palmately lobed. Stamens 7‒14 in 2 whorls, anthers entire; pistillode absent. Pistillate flowers with triangular disc glands; stigmas 3(‒5)

Vernicia

80a.

Glands in margin (not near!) near petiole insertion, can be two round dots per side (then stamens dichotomously splitting!)

81

80b.

Glands in teeth or various types of extrafloral nectaries along margin or midrib, not in margin. Stamens not splitting

82

81a.

Latex white. Hairs absent. Inflorescences a single sex. Staminate flowers with 3 stamens. Pistillate flowers with apically non-split stigmas

Excoecaria

81b.

Latex, if present, not obvious. Hairs present. Staminate flowers with dichotomously splitting stamens, arising from 4‒7 androphores, with ultimately more than 100 stamens. Pistillate flowers with apically split stigmas

Spathiostemon

82a.

Leaf blades with extrafloral nectary areas adaxially and/or abaxially, sometimes gland-like

83

82b.

Leaf blades without extrafloral nectaries; marginal teeth can end in glands

91

83a.

Leaf blades below with two subbasal extrafloral nectaries (naked eye) and a row of several submarginal/marginal small glands (hand lens). Plant glabrous. Stamens 2. Ovary and fruits 2-locular; fruits indehiscent berries

Balakata

83b.

Leaf blades below or above with extrafloral nectaries of same size. Plants with hairs, or glabrous. Stamens 3 or more. Ovary and fruits 2- or more locular, when 2-locular then parts hairy; fruits dehiscent capsules

84

84a.

Extrafloral nectaries along margin (usually abaxially)

85

84b.

Extrafloral nectaries along midrib or parenchyma, not restricted to margin

88

85a.

Submarginal circular extrafloral nectaries on both sides; leaf blades elliptic, 8.4‒13.5 cm long, margin entire. Pistillate sepals 5 or 6, bract-like, in two whorls

Clonostylis

85b.

Submarginal extrafloral nectaries only abaxially; leaf blade margin entire to serrate. Pistillate sepals in one whorl, either 3 (triangular) or 5 (ovate and then leaf blades long obovate, 8‒56 cm long)

86

86a.

Leaf blades obovate, 8‒56 cm long. Stamens 16‒26. Pistillate sepals 5, ovate; stigmas apically split

Wetria

86b.

Leaf blades ovate to elliptic to oblong, 5‒23 cm long. Stamens 3. Pistillate sepals 3, triangular; stigmas apically undivided

87

87a.

Leaf blade margin entire. Staminate bracts glandless or with a pair of globose-cylindrical glands touching the axis of the thyrse. Fruit pedicel 5‒17 cm long

Gymnanthes

87b.

Leaf blade margin serrate. Staminate bracts at base with a pair of elliptical glands touching the axis of the thyrse and sometimes decurrent. Fruit pedicel 0.8‒3 cm long

Shirakiopsis

88a.

Extrafloral nectaries abaxially in teeth, basal ones larger. Fruit columella basally with strand-like remnants of sutures after dehiscence. Stamens 9‒25, thecae apically touching on top of connective. Pistillate inflorescence short, consisting of a single, hanging flower. Blade of older leaves often with lobes

Baliospermum

88b.

Extrafloral nectaries in rows near midrib or basally or apically concentrated in leaf blades. Fruit columella without basal remnants of sutures. Stamens 4‒8 or 30‒120, thecae along connective. Pistillate inflorescences with more than 1 flower. Blade of older leaves not lobes

89

89a.

Staminate inflorescences panicles. Stamens 4, 6 or 8, inserted on a ring-like collar of receptacle. Staminate bracts usually with 2 basal glands outside. Stigmas apically not to seldom split

Alchornea

89b.

Staminate inflorescences racemiform or paniculate. Stamens 30‒120, inserted directly on receptacle. Staminate bracts without glands. Stigmas deeply split apically

90

90a.

Stipules linear-triangular, 7‒20 by 2‒3 mm (all W Malesia), base amplexicaul, to 2 cm below the leaves. Stamens 30 or 31, with disc lobes among the stamens, disc annular in pistillate flowers. Ovary and fruits 3-locular. Seeds apically with a caruncle

Chondrostylis

90b.

Stipules triangular, 1.5‒5 by 0.75‒2 mm, or 4‒45 by 0.5‒5 mm on New Guinea, not amplexicaul, next to leaves. Stamens 40‒120. Disc in both sexes absent. Ovary and fruits 2- or 3- (or 4-)locular. Seeds without a caruncle

Cleidion

91a.

Inflorescences bisexual, cymose (often corymbiform), with pistillate flowers ending every primary branch. Leaf blades often basally lobed 

Jatropha

91b.

Inflorescences unisexual or bisexual, then racemose to paniculate thyrses, with pistillate flowers in lower part when bisexual, sometimes flowers single when cauliflorous or ramiflorous. Leaf blades usually unlobed (Baliospermum excepted)

92

92a.

Herbs to subshrubs (< 2 m high). Leaf blades elliptic to linear, margin with dense, minute glandular teeth. Bracts of staminate flowers with a pair of glands. Latex absent. Stamens 3. Ovaries and fruits with 6 rows of small spines, 2 rows per locule 

Microstachys

92b.

Herbs to trees. Leaf blades of various shapes, margin at most laxly glandular toothed. Bracts of staminate flowers with (Excoecaria, then white latex present) or without glands. Stamens 3‒250. Ovaries and fruits smooth or completely covered with spines

93

93a.

Both sexes with petals (check for scars within sepals/ calyx with fruits)

94

93b.

Both sexes without petals

97

94a.

Stamens 3 or 5, united. Petals of various colours, including white and yellow

Trigonostemon

94b.

Stamens 6‒20, free to (partly) united. Petals white (or yellow or light green) 

95

95a.

Petals smaller to slightly larger than sepals (up to 2.5 mm long). Inflorescences often superposed (or single or in groups)

Agrostistachys

95b.

Petals larger than sepals (more than 2.5 mm long). Inflorescences single or in small groups, not superposed

96

96a.

Inflorescences narrowly paniculate to racemose, basal bracts stipule-like. Stamens 7‒20, in 3 whorls, outer with free stamens, inner two with filaments connate into an androphore. Pistillate sepals enlarging in fruit

Tritaxis

96b.

Inflorescences panicles, basal bracts leaf-like. Stamens 6 or 8 in 2 whorls (4 or 5 in outer, 1–3 in inner), filaments only basally connate. Pistillate sepals not enlarging in fruit

Tapoides

97a.

Leaf blades subpeltate. Inflorescences to 1 cm long. Stamens 200‒250. Ovaries and fruits densely echinate, spines in fruit soft, up to 9 mm long

Hancea

97b.

Leaf blades basally attached. Inflorescences longer than 1 cm. Stamens 3‒66. Ovaries and fruits smooth or if echinate, then spines hard or soft and less than 8 mm long

98

98a.

Latex white. Stamens 3. Stigmas apically not split. Fruits after dehiscence with caruncle remaining attached to column, seeds naked

Excoecaria

98b.

Latex absent or not obvious. Stamens 8‒50. Stigmas apically laciniate or not split. Seeds covered by arilloid, with apical caruncle (not remaining attached to columella) or naked

99

99a.

Stamens 8, anthers vermiform. Pistillate flowers with large bracts covering flowers. Allomorphic flowers sometimes present. Stigmas laciniate

Acalypha

99b.

Stamens 18‒50, anthers not vermiform, thecae not elongated. Pistillate flowers with stipule-like bracts, partly covering flowers at most. Allomorphic flowers absent. Stigmas apically not split

100

100a.

Leaf blades when dried often sandpaper-like. Thecae upright on connective. Staminate disc glands strap-like, among stamens, with apical tuft of hairs; pistillate disc annular, 5-lobed. Stigmas highly papillate above

Claoxylon

100b.

Leaf blades smooth. Thecae hanging from connective. Staminate disc absent, pistillate one consisting of 3 lobes. Stigmas with at most short papillae above

Micrococca

 

 

Key to the Genera of Malesian Pandaceae

 

1a.

Flowers in terminal or cauliflorous, pendulous inflorescences. Leaf blades without glands along the margin. Calyx lobes valvate. Fruits hairy (when young)

Galearia

1b.

Flowers in axillary fascicles to shortly peduncled after several flowering periods. Leaf blade margins with glandular teeth or crenations. Calyx lobes imbricate. Fruits glabrous

Microdesmis

 

 

Key to the Genera of Malesian Peraceae

 

1a.

Petals absent (though inner sepal may look petal-like, then single). Fruits covered with glochidiate (long stinging), simple hairs

Chaetocarpus

1b.

Petals 5. Fruits tomentose with normal hairs, these simple and stellately bundled

Trigonopleura

 

 

Key to the Genera of Malesian Phyllanthaceae

 

1a.

Leaves 3-foliolate

Bischofia

1b.

Leaves simple

2

2a.

Fruits 2-lobed, usually heart-shaped, samara-like capsules. Hairs simple or scale-like, latter on branches, lower leaf blade surfaces and bracts

Hymenocardia

2b.

Fruits 2- to more lobed capsules to berries to drupes, not heart-shaped and not samara-like. Hairs simple (to stellately bundled), never scale-like

3

3a.

Petals present in both sexes

4

3b.

Petals absent in both sexes (disc lobes sometimes appearing as petals!)

9

4a.

Petals longer than sepals, cucullate (except straight in pistillate flowers of one species)

Dicoelia

4b.

Petals shorter than sepals, straight, not cucullate

5

5a.

Disc split into petal-like glands, these bilobed (5) or completely split (seemingly 10), opposite petals, often larger than petals

6

5b.

Disc circular, often lobed, not split into separate glands

7

6a.

Woody herbs to subshrubs, with a sparse covering of simple hairs, not easy to see by the naked eye. Leaves elliptic to somewhat obovate, 1‒7.6 cm long. Seeds whitish to dark brown, smooth, rugose or pitted

Leptopus

6b.

Shrubs, completely covered with hairs c. 1 mm long, visible to the naked eye. Mature leaf blades obovate, 0.9‒2.5 cm long. Seeds intensely black, rugose

Notoleptopus

7a.

Disc a thin to fleshy ring, without additional cupular part in pistillate flowers. Stamens around pistillode, free or filaments basally connate. Flowers single or in pairs when axillary, only in short racemes when cauli- or ramiflorous. Stigma tips slightly thickened and bent horizontally, persistent. Fruits capsules

Actephila

7b.

Disc a fleshy horizontal ring, with additional cupular part in pistillate flowers. Filaments partly united into androphore with on top the pistillode. Flowers in axillary glomerules or seemingly in inflorescences when branches leafless. Stigma tips not thickened, usually caducous. Fruits capsules or drupes

8

8a.

Fruits drupes. Leaves usually dull greyish brown when dry, with scalariform venation and in one section of genus nerves ending in marginal vein, in other section looping and anastomosing before margin

Bridelia

8b.

Fruits capsules. Leaves usually shiny, different colours when dry, also brown, with indistinct venation, looping and anastomosing before margin

Cleistanthus

9a.

Disc present (either ring-like or separate glands, sometimes petaloid in appearance)

10

9b.

Disc absent (sometimes scales on sepals, not on receptacle)

13

10a.

Flowers in (branching) racemes. Connective of stamens broad, with thecae separately on top (resembling Mickey Mouse head). Fruits drupes, often laterally compressed, style terminal to lateral

Antidesma

10b.

Flowers in axillary fascicles to panicles. Thecae along connective, not on top. Fruits capsular to sometimes berries or drupes, not flattened, style terminal

11

11a.

Pistillode 3-partite. Stamens free. Disc ring-like

Flueggea

11b.

Pistillode absent. Stamens free or united into androphore. Disc ring-like or separate glands

12

12a.

Sepals 4, horizontal. Disc annular in both sexes. Stigmas sharply bent horizontal. Sarcotesta (fleshy layer) blue

Margaritaria

12b.

Sepals 4–6, generally diagonally upright. Disc annular in pistillate flowers to generally separate (often petal-like) disc glands in staminate flowers. Stigmas upright to gradually bent horizontal. Seeds without a sarcotesta

Phyllanthus

13a.

Flowers in axillary fascicles

14

13b.

Flowers in inflorescences, generally racemose/spicate thyrses, cauliflorous to axillary

16

14a.

Staminate sepals without scales inside. Stigmas united into a pyramidal cone (free in G. sericeum). Stamens with united filaments; thecae at end of filaments, upright, seemingly also united, but separating when flower older

Glochidion

14b.

Staminate sepals with scales or without scales inside; if without scales then stigmas free (otherwise partly connate). Thecae either along androphore or free from each other (horizontal to oblique)

15

15a.

Fruits broader than high; seeds smooth. Staminate sepals with and without scales (then sepals folded inwards). Staminate flowers with thecae along androphore with scales at sepal apices

Breynia

15b.

Fruits higher than broad; seeds with rough surface (unknown for S. sphenophyllus: thecae along androphore but sepals without scales). Staminate sepals straight, not folded, with scales (littoral S. bacciformis: androphore apically splitting into three wings with thecae underneath) or without (S. sphenophyllus: thecae along androphore)

Synostemon

16a.

Staminate sepals with a scale inside. Ovaries flat on top with stigmas horizontal, split, like crescent-shaped moons

Breynia

16b.

Staminate sepals without scales inside. Ovaries not flat, stigmas upright, apically usually lobed, but not resembling crescent-shaped moons

17

17a.

Staminate flowers with massive pistillode (broader than anthers). Woody endocarp dehiscing partly loculicidally and septicidally and becoming flat and star-like; columella with basally a thickened ring where exo- and mesocarp were attached. Stipules early caducous, leaving almost ring-like, blackish scars 

Ashtonia

17b.

Staminate flowers with small pistillode (narrower than anthers). Endocarp splitting partly or completely, but never forming flat, star-like structure; columella without basally thickened ring.Stipules persistent to early caducous, leaving small scars

18

18a.

 Leaves distichous. Candelabriform (Terminalia-)branching pattern absent. Stamens 2–4 (Aporosa, unknown for Distichirops). Petioles 4–51 mm long. Hairs simple, not stellately bundled. Hairs on apical bud scales normal, not papillae-like

19

18b.

Leaves opposite to spirally arranged, candelabriform branching pattern strong to weak. Stamens 3–10. Petioles 4–184 mm long. Hairs simple or stellately bundled. Hairs on apical bud scales short, papillae-like

20

19a.

Pistillate flower with a single bract. Pedicels without abscission zones. ― Staminate flowers generally very compact, individual flowers difficult to see

Aporosa

19b.

Pistillate flowers with 3 bracts. Pedicels with abscission zone. ― Staminate flowers unknown

Distichirhops

20a.

Stamens shorter than sepals. Hairs simple or stellately bundled. Sepals slightly fused at base. Leaves spirally arranged. Stipules triangular. ― Malesia, Pacific

Baccaurea

20b.

Stamens longer than sepals. Hairs simple. Sepals fused at base. Leaves opposite to spiral. Stipules triangular to leaf-like. ― Pacific

Nothobaccaurea

 

Key to the Genera of Malesian Picrodendraceae

 

1a.

Leaves opposite

2

1b.

Leaves spirally arranged

3

2a.

Leaf blade margin entire to very laxly crenate, with very small glandular dots or teeth in shallow cavities. Stipules absent. Fruit lobes not horned. Seeds with caruncle consisting of short to longer papillae. Staminate receptacle raised, disc-like

Austrobuxus

2b.

Leaf blade margin crenate to serrate with 20–40 short teeth, not ending in teeth. Stipules present, up to 1.8 mm long. Fruit lobes horned with stigma remnants. Seeds naked, no fleshy attachment. Staminate receptacle flat, no disc

Choriceras

3a.

Leaf blade apex caudate, lower surface glabrous. Stamens 10–14; filaments free. Stigmas spade-like

Kairothamnus

3b.

Leaf blade apex rounded to apiculate, lower surface sericeous. Stamens 28–68; filaments united. Stigmas petal-like

Petalostigma

 

Putranjivaceae

 

Drypetes