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Flora of Thailand
Euphorbiaceae |
This chapter is added, because usually in floras one first has to identify the genus and then in a next key the species. However, the distinction betweeen the genera Hancea, Macaranga, and Mallotus is difficult (number of locules in the stamens and the dehiscence of the fruits). Most people recognize a plant as belonging to this group, but they do not know the exact genus name. Therefore, this key makes identification up to genus level superfluous.
This page differs from the Flora of Thailand edition, Trewia is now part of Mallotus, and a part of Mallotus has become Hancea.
1a. |
All or most leaves alternate (sometimes opposite beneath inflorescence; inflorescence always in the axil of a leaf) |
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1b. |
All leaves opposite (in some species opposite leaf stipule-like and caducous, then inflorescence opposite to leaf) |
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2a. |
Leaves 1 cm or more peltate |
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2b. |
Leaves less than 1 cm peltate |
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3a. |
Twigs hollow, ant-inhabited |
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3b. |
Twigs solid, not ant-inhabited |
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4a. |
Twigs densely whitish glaucous |
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4b. |
Twigs not glaucous |
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5a. |
Leaves trilobed with the central lobe narrowly ovate, substantially longer and wider than the lateral lobes. Fruits 4–5 locular |
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5b. |
Leaves trilobed with the lobes broadly ovate, more or less equal in size and shape. Fruits 2 or 3 locular |
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6a. |
Lower surface of leaf blade intensely white. Stipules triangular. Fruits 3-locular. Dry land |
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6b. |
Lower surface of leaf blade not white. Stipules broadly rounded. Fruits 2-locular. Swamps |
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7a. |
Mature leaves broadly ovate, trilobed. Young leaves reddish brown furfuraceous. Staminate bracteoles rounded to broadly acute, rusty furfuraceous |
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7b. |
Mature leaves narrowly ovate, usually entire, or with short lateral cusps. Young leaves green, glabrous. Staminate bracteoles caudate, glabrous |
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8a. |
Leaves and twigs massive. Leaf blades usually at least 40 cm long. Stipules large, usually longer than 20 mm |
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8b. |
Leaf blades shorter than 35 cm, rarely more. Stipules shorter than 15 mm |
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9a. |
Twigs with silvery, harsh persistent hairs. Petioles D-shaped in section. Upper leaf surface without prominent extrafloral nectaries. Peninsular |
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9b. |
Twigs with soft, light-brown caducous hairs. Petioles round in section. Upper leaf surface with prominent extrafloral nectaries near the leaf apex. Absent from Peninsular |
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10a. |
Leaves trilobed, lobes more than 5 cm long |
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10b. |
Leaves not lobed (or sometimes lobed, but then lobes up to 5 cm long) |
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11a. |
Upper leaf blade surface without (basal) extrafloral nectaries |
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11b. |
Upper leaf blade surface with extrafloral nectaries, at least close to insertion with petiole |
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12a. |
Leaves, twigs, inflorescence axes and bracteoles glabrous |
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12b. |
With scattered to very dense hairs on most parts |
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13a. |
Leaf blades thick, often drying chocolate brown, margin recurved. Staminate bracteoles entire. Fruits smooth, without spines |
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13b. |
Leaves thinly papery, drying pale brown, margin not recurved. Staminate bracteoles deeply irregularly dissected. Fruits with long tentacle-like spines |
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14a. |
Lower leaf blade surface and branches distinctly hairy to the touch |
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14b. |
Lower leaf blade surface glabrescent (sometimes hairy to the touch), branches not distinctly hairy |
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15a. |
Indumentum floccose (among hairs are strap-like enations densely covered with hairs, providing an irregular indumentum layer) |
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15b. |
Indumentum in a regular layer, not floccose |
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16a. |
Glandular scales absent from upper leaf surface; apical extrafloral nectaries usually absent. Plants not smelling of fenugreek. Fruits densely set with c. 400 c. 7 mm long spines. Stamens 70-80 |
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16b. |
Glandular scales on upper leaf surface, mainly near insertion; apical extrafloral nectaries usually present. Plants (usually) smelling of fenugreek. Fruits set with less than 100, less than 5 mm long spines. Stamens 40-50 |
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17a. |
Margin of leaf blade entire. Stellate hairs absent |
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17b. |
Margin of leaf blades serrate or with a few short teeth. Stellate hairs present |
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18a. |
Leaves deltate, c. 1 cm peltate. Leaf base strongly truncate to square. Staminate bracteoles indistinct, smaller than the flower clusters. Extrafloral nectaries aggregated at petiole insertion |
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18b. |
Leaves ovate, >2 cm peltate. Leaf base rounded, not truncate. Staminate bracteoles prominent, larger than the flower clusters. Extrafloral nectaries near leaf base and/or apex |
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19a. |
Stipules elliptic, c. 3 by 1 mm. Staminate and pistillate bracts tiny, inconspicuous, 1 mm, rounded, bracteoles similar but smaller. Widespread, common |
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19b. |
Stipules oblong-acute, c. 6 by 2 mm. Pistillate bracts obovate, to 11 by 2 mm, crenate, with numerous conspicuous marginal glands, bracteoles similar but smaller. Staminate unknown. Peninsular, once collected |
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20a. |
Leaf blades nearly always with a few conspicuous elongate extrafloral nectaries on main nerves somewhat distant from petiole insertion. Staminate inflorescence branches usually strongly zigzag. Staminate bracteoles spoon-like with 1-2 subapical glands |
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20b. |
Leaf blades with round extrafloral nectaries near the basal and apical leaf margins. Staminate inflorescence branches not strongly zigzag. Staminate bracteoles ovate, apex rounded to broadly acute |
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21a. |
Leaf blades about as long as wide (length/width ratio 1.3–1.4). Plant distinctly smelling of fenugreek. Pistillate sepals recurved below ovary, not enclosing ovary and style, persistent |
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21b. |
Leaf blades much longer than wide (length/width ratio 1.8–3.8). Plant usually not or slightly smelling of fenugreek. Pistillate calyx urceolate around ovary and style, caducous |
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22a. |
Stellate hairs absent (or occasionally a single one: Mallotus subpeltatus), only simple hairs |
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22b. |
Stellate hairs present (next to simple ones) |
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23a. |
Inflorescences up to 1 cm long. Stamens 200-250. Leaves subpeltate, margin entire. Ovary and fruit 3-locular. Fruits with spines |
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23b. |
Inflorescences much longer. Stamens less than 20. Leaves not peltate to subpeltate, margin entire to dentate. Ovary and fruit 2-locular. Fruits with or without spines |
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24a. |
Twigs hollow, ant-inhabited. Leaf blades with 3 equal lobes |
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24b. |
Twigs solid, not ant-inhabited. Leaf blades either entire or if trilobed with central lobe much larger than laterals |
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25a. |
Stipules and bud scales finely pointed, erect and clustered at the twig apex. Primary forest |
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25b. |
Stipules triangular or elliptic, sometimes recurved, not crowded with bud scales at twig apex. Secondary forest |
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26a. |
Stipules and bud scales chocolate (dark) brown, with sparse spreading white whiskers. Pistillate spikes with terminal flowers and fruits. Staminate spikes threadlike, flower clusters 1–1.5 mm across, never malformed |
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26b. |
Stipules and bud scales chestnut (light) brown, glabrous. Pistillate flowers and fruits spaced along top ½–¼ of spike. Staminate spikes with 1 mm axis, flower clusters 3–4 mm across, often malformed as witches' brooms (many, tightly packed flowers) |
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27a. |
Twigs, petioles and especially inflorescence axes with long spreading silvery-white hairs. Staminate bracteoles minute, often absent. Fruits subtended by large opposite leaf-like bracts |
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27b. |
Twigs, petioles and inflorescence axes often tomentose or shortly pubescent, but without long spreading silvery hairs. Staminate bracteoles prominent and larger than the flower clusters. Fruits subtended by small caducous bracts |
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28a. |
Leaves densely coarsely pubescent on upper surface; margin coarsely toothed. Fruits covered in long thin spines. Bushy tree with sprawling limbs |
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28b. |
Leaves glabrous above; margins entire. Fruits without spines. Small erect trees |
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29a. |
Stipules elliptic including a long narrow tip 10 by 1.5 mm, erect. Bracteoles ovate to 10 by 6 mm with distant long, linear blunt teeth |
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29b. |
Stipules triangular, c. 10 by 4 mm, acuminate, recurved. Bracteoles of ovate outline 8 mm long, deeply finely dissected (laciniate), sometimes with no central lamina |
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30a. |
Leaf blades ovate, length/width ratio up to 1.8 (blades about as long as broad to less than 2x as long as broad), with 2 lobes or not (measure!, because some species seem to have long blades) |
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30b. |
Leaf blades ovate to obovate, length/width ratio 1.7 (elliptic) or more, lobes absent |
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31a. |
Upper surface of leaf blades with orangish glandular scales, especially near insertion (use hand lens or microscope) |
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31b. |
Upper surface of leaf blades without glandular scales (only present on lower surface) |
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32a. |
Leaf blades below (sub)glabrous to glabrescent, at most few hairs on veins |
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32b. |
Leaf blades below densely hairy: dense indumentum on veins (and often on epidermis, then leaves whitish beneath) |
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33a. |
Scandent shrub to woody climber. Lower leaf blade surface not whitish (hairs only on venation, epidermis visible). Inflorescences mainly axillary, not branching. Stamens c. 50. Ovary and fruit smooth, no spines, 2-locular |
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33b. |
Shrubs to trees. Lower leaf blade surface whitish (epidermis also densely hairy). Inflorescences mainly terminal, branching. Stamens 45 to more. Ovary and fruit with spines, (2)3-4(5)-locular |
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34a. |
Leaves usually broadest above lower third to middle, base (narrowly emarginate to round to) usually cuneate with two large extrafloral nectaries, (1-3) by (1-)2 mm; margin often with 1 or 2 lobes, up to 3.5 cm long. Ovary and fruits sparsely set with c. 30 hard spines |
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34b. |
Leaves broadest below lower third, base emarginate to rounded, with 2 to more extrafloral nectaries, 1-2.5 by 0.3-1.3 mm (sometimes confluent and then seemingly much larger); margin without or with a single extremely short lobe (less than 1 cm: M. tetracoccus). Ovary and fruits densely set with 100 or more hard or soft spines |
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35a. |
Peltate part of leaf blade usually folded upwards; lower surface usually with pocket domatia full with hair tufts. Fruit (and ovary) covered with one continuous layer of soft spines, individual spines nor fruit wall visible. P |
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35b. |
Peltate part of leaf blade absent or flat; lower surface without domatia. Fruits (and ovary) covered with far less spines, individual spines (and, in older fruits, fruit wall) visible |
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36a. |
Upper surface of leaf blade usually without or 1 or 2 apical extrafloral nectaries; glandular scales on lower surface not visible. Staminate flowers with 3 sepals; stamens 70-80. Fruit set with c. 400 soft spines, up to 7 mm long |
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36b. |
Upper surface of leaf blade usually with (0 to) few to many apical extrafloral nectaries; glandular scales on lower surface visible (microscope!, sometimes rare). Staminate flowers with (2)4-5(6) sepals; stamens 45-65. Fruit set with c. 100 stiff spines, up to 3 mm long |
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37a. |
Lower leaf surface whitish because of dense hairs on venation and epidermis. Ovary and fruits without spines |
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37b. |
Lower leaf surface (sub)glabrous to densely hairy on venation only (not whitish, epidermis visible; use microscope). Ovary and fruits armed or not, with or without spines |
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38a. |
Glandular scales yellowish. Stipules 3.5-5.5 mm long. SW (Sam Roi Yot) |
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38b. |
Glandular scales red or greenish (orange when fresh). Stipules 0.5-1.5 mm long. All over Thailand |
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39a. |
Glandular scales greenish when dry (orange when fresh) , only visible on fruits, scarcely visible on lower leaf surface. Fruits 11-14 by c. 11 mm, wall 2-3 mm thick. N (Kamphaeng Phet) |
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39b. |
Glandular scales reddish, well visible on fruits and lower leaf surface. Fruits 8-12 by 6-8 mm, wall less than 2 mm thick. All over Thailand |
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40a. |
Leaf blades on upper surface with orangish glandular scales (hand lens or microscope), (sub)glabrous. Fruits winged or not, indehiscent or tardily (late) dehiscent |
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40b. |
Leaf blades on upper surface without glandular scales, only present on lower surface, glabrous to densely hairy. Fruits never winged, dehiscing |
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41a. |
Leaf blades 9.8-27 cm long, often with hair tuft domatia in nerve axils beneath. Stamens 26-37, filaments 1.5-3 mm long. Ovary and fruit not winged, tardily dehiscent. Stipules 1.5-2.5 mm long |
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41b. |
Leaf blades 5.5-16 cm long, without domatia underneath. Stamens 20-25, filaments 0.5-1.5 mm long. Ovary and fruits with upward pointing wings, indehiscent. Stipules 0.7-0.9 mm long |
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42a. |
Leaf blades ovate, widest basally or below lower third, (sub)glabrous. N |
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42b. |
Leaf blades elliptic or obovate, widest at lower third or higher, (sub)glabrous to hairy on nerves. All over Thailand |
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43a. |
Glandular scales on lower leaf blade surface few. Stamens 25-35. Ovary and fruits armed with spines |
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43b. |
Glandular scales on lower leaf blade surface distinct. Stamens 55-70. Ovary and fruits without spines |
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44a. |
Leaf blade elliptic, margin subentire with glandular teeth. SW (Kanchanaburi), P |
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44b. |
Leaf blade ovate, margin entire. SW (Sam Roi Yot) |
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45a. |
Opposite leaf reduced to stipule or orbicular / heart-shaped (different in shape from opposite leaf). Inflorescences opposite to large leaf. --- Plants rare, only in the Peninsula |
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45b. |
Opposite leaves of same shape, one usually somewhat smaller. Inflorescences in axil of smaller leaf |
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46a. |
Petioles less than 2 cm long |
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46b. |
Petioles longer than 2 cm |
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47a. |
Blade of smaller leaf orbicular / heart-shaped, 0.8-5.5 by 0.8-4.8 cm |
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47b. |
Blade of smaller leaf stipule-like, triangular, 4-10 by 1.5-2.5 mm |
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48a. |
Leaf blades hairy underneath |
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48b. |
Leaf blades glabrous underneath |
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49a. |
Length/width ratio of leaf blades less than 1.8(-1.9) (leaf blade about as broad as long to up to 1.8-1.9 times as long as broad) |
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49b. |
Length/width ratio of leaf blades more than 1.8 (leaf blades about twice to more as long as broad) |
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50a. |
Leaf blades ovate, margin entire. Deciduous, flowering when young leaves appear. Fruits indehiscent drupes. Stellate hairs often very long and soft |
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50b. |
Leaf blades ovate to obovate, margin subentire to dentate. Not deciduous, flowering when in full leaf. Fruits dehiscent capsules. Stellate hairs short to long, not soft |
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51a. |
Lower leaf blade surface densely tomentose, hairs also on epidermis, epidermis not visible; glandular scales orange; margin subentire (few teeth).---Near sea |
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51b. |
Lower leaf blade surface subglabrous to hairy on nerves only, epidermis visible; glandular scales yellow, orange or reddish; margin dentate |
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52a. |
Leaf blade elliptic to obovate; glandular scales many on lower surface (microscope). Stipules 4-10 by 1.2-6 mm (large) |
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52b. |
Leaf blade ovate (to obovate); glandular scales almost absent to few on lower surface (microscope). Stipules 1.6-5.5 by 0.5—1.5 mm (smaller) |
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53a. |
Stipules 1.2-1.5 mm wide. Upper leaf blade surface drying brownish-greenish, basally with 2 large extrafloral nectaries, 0.5-2 by 0.5-1 mm |
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53b. |
Stipules 2-6 mm wide. Upper leaf blade surface drying greenish, basally with 2 to many small extrafloral nectaries, 0.3-0.5 by 0.3-0.5 mm |
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54a. |
Lower leaf blade surface only along the very basal edge with a few glandular scales. Staminate sepals 3; stamens c. 50. Pistillate sepals 5 or 6; stigmas c. 4.2 mm long |
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54b. |
Lower leaf blade surface all over with a few glandular scales. Staminate sepals 4 or 5; stamens 25-35. Pistillate sepals 4 or 5; stigmas 1.8-2.3 mm long |
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55a. |
Venation penninerved (basal nerves not distinctly different from others) |
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55b. |
Venation palmate or triplinerved (basal nerves more distinct than others) |
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56a. |
Leaf petiole 0.2-0.4 cm long |
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56b. |
Leaf petiole 0.1-8 cm long (always leaves with petiole longer than 0.4 cm) |
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57a. |
Staminate inflorescences up to 43 cm long; pistillate ones up to 28 cm |
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57b. |
Inflorescences less than 10 cm long |
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58a. |
Stipules needle-like, 3-6.2 by 0.4-0.5 mm (narrow). Upper leaf blade surface without extrafloral nectaries |
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58b. |
Stipules broader, 2-9 by 1-3 mm (broader). Upper leaf surface with extrafloral nectaries, especially basally |
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59a. |
Fruits and petioles densely hairy. Lower leaf surface hairy or midrib hairy. — SE, P |
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59b. |
Fruits and petioles glabrous to densely hairy. Lower leaf blade surface (sub)glabrous to sparsely hairy. — NE, SE, P |
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60a. |
Glandular scales absent. Blade apex caudate, lower leaf surface densely hairy only on midrib — P |
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60b. |
Glandular scales whitish, sparsely present near base on lower leaf surface. Blade apex acuminate, lower leaf surface hairy |
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61a. |
Margin of leaf blade crenulate to subentire to denticulate with glandular teeth |
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61b. |
Margin of leaf blade entire or with a single subapical tooth per side |
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62a. |
Upper surface of leaf blade with 4–8 marginal extrafl oral nectaries per side. Pistillate infl orescences (staminate ones unknown) reduced to single, terminal fl ower surrounded by bracts
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62b. |
Upper surface of blade with 2 or 3 extrafl oral nectaries near base close to midrib. Infl orescences up to 6.3 cm long |
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63a. |
Leaf margin with a single subapical tooth per side, apex acuminate, upper surface with extrafl oral nectaries in loops of nerves. Fruits smooth. — NE |
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63b. |
Leaf margin without teeth, apex bluntly acute, upper surface with extrafl oral nectaries on nerves except above third nerve. Fruits with spines. — P |
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64a. |
Staminate inflorescences less than 4 cm long; pistillate inflorescences up to 4 cm long or up to 8 cm long, but then inflorescences umbelliform |
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64b. |
Staminate inflorescences more than 5 cm long, pistillate ones up to 12 cm long, never umbelliform |
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65a. |
Leaf blades elliptic; upper surface without extrafloral nectaries; lower surface subglabrous to somewhat hairy on venation. Staminate and pistillate inflorescences up to 2 cm long, not umbelliform. Stamens c. 25. Fruits without spines |
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65b. |
Leaf blades ovate (to elliptic); upper surface with extrafloral nectaries, especially basally; lower surface subglabrous to densely hairy. Staminate and pistillate inflorescences up to 2-8 cm long. Stamens 20-30 (leaves hairy beneath) or 40 or 60. Fruits with or without spines |
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66a. |
Lower leaf blade surface subglabrous to hairy on venation, hair tuft domatia present in all or most nerve axils. Stamens c. 60. Pistillate sepals 5-5.2 mm long; ovary spiny |
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66b. |
Lower leaf blade surface densely hairy, hair tuft domatia absent or only in basal nerve axils. Stamens 20-40. Pistillate sepals 3-4 mm long; ovary spiny or smooth |
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67a. |
Lower leaf blade with hair tuft domatia in basal nerve axils. Ovary and fruit smooth. Pistillate inflorescence a raceme. Stamens 20-30 |
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67b. |
Lower leaf blade without hair tuft domatia. Ovary and fruit with spines. Pistillate inflorescence umbelliform. Stamens c. 40 |
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68a. |
Leaf blades ovate |
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68b. |
Leaf blades elliptic to obovate |
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69a. |
Fruits indehiscent drupes, smooth, no spines. Leaf blade margin entire |
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69b. |
Fruits dehiscent capsules, with or without spines. Leaf blade margin laxly denticulate or serrulate |
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70a. |
Fruits smooth, without spines. Lower leaf blade surface densely hairy with hair tuft domatia in basal nerve axils, glandular scales whitish |
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70b. |
Fruits with spines. Lower leaf blade surface subglabrous to densely hairy on venation, hair tuft domatia absent, glandular scales yellow |
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71a. |
Leaves drying brownish (if greenish, then nerves not yellowish) |
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71b. |
Leaves drying greenish, nerves drying yellowish |
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72a. |
Stipules 2-6 mm wide (4-10 mm high). Upper surface of leaf blade basally with 2-12 small (0.3-0.5 mm in diameter) extrafloral nectaries on each side along margin |
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72b. |
Stipules 0.5-2 mm wide (1.6-6.3 mm high). Upper surface of leaf blade basally with 1-2 pairs of large extrafloral nectaries (0.5-2 mm in diameter), sometimes smaller additional ones along margin |
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73a. |
Leaf blades distinctly obovate (to smaller ones sometimes elliptic), margin dentate, upper surface basally usually at least with 2 relative large extrafloral nectaries on basal nerves, up to 5 per leaf side, up to 1 by 0.5 mm |
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73b. |
Leaf blades elliptic to obovate, margin denticulate, upper surface with 1 or 2 basal pairs of large extrafloral nectaries (0.5-2 mm in diameter) or 1-3 pairs of small extrafloral nectaries (up to 0.7 mm) |
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74a. |
Stipules 1.2-1.5 mm wide. Bracts 3-8.2 by 2-3 mm. Extrafloral nectaries on upper blade surface large, 0.5-2 mm in diameter. P |
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74b. |
Stipules 0.5-1.1 mm wide. Bracts 1-4 by 0.6-0.7 mm. Extrafloral nectaries on upper blade surface small, up to 0.7 mm in diameter. All over Thailand |