The Macaranga Dioica group (and key to New Guinean Pseudorottlera too)
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Shrubs or small trees, rarely to 20 m. Stipules usually persistent, ovate to elliptic (subulate in M. punctata var. subulata). Leaves penninerved or palmate with 2 basal lateral nerves as prominent as midrib, very rarely 3-lobed, nearly always with several, usually small, glands near petiole insertion and usually on the main nerves, apex acute or rarely caudate, below often softly hairy. Staminate inflorescences racemes or panicles with slender, often sinuous, usually divaricate sometimes opposite branches; bracts often persistent; flower clusters rather small, sometimes crowded catkin-like at branch tips; bracteoles small, usually smaller than cluster, persistent, with or without adaxial patellar glands. Pistillate inflorescences commonly spikea, the flowers and fruits crowded at the apex of a long bare peduncle, rarely a raceme, with 1–2 lateral clusters towards apex, subtended by often persistent leafy bracts. Fruits (1–)2-locular, to 1–2 cm across, thinly woody, usually granular glandular, usually variously spiny, often the spines close and soft and sometimes hairy; styles sometimes lateral, smooth, papillose or plumose, often caducous.
Habitat & Ecology — All below 1000m, except M. lugubris, M. dioica var. glabra, and varieties of M. rufibarbis and M. strigosa. About half the species in primary, the others in secondary forest.
Notes — 1. This is the biggest group in New Guinea and most of the species are endemic to the New Guinea mainland (see above). The group takes its name from wide-ranging M. dioica, described from collections make on Cook's circumnavigation.
2. Two species (M. astrolabica, M. hoffmannii) are placed here solely on basis of their descriptions.
3. This group has similarities to Section Pseudorottlera in that most species have a spicate infructescence with the fruits subtended by leafy bracts. In Whitmore (in Airy Shaw, Kew Bull., Addit. Ser. 8, 1980) I was misled to put M. quadriglandulosa here from its spicate infructescence, not with M. tanarius which it otherwise closely resembles.
4. Eight of the nine species of Section Mecostylis (Kurz) Pax & K.Hoffm., which are still recognised, all fall into this group [the ninth, M. stenophylla, is in the Brunneofloccosa group; Eds.].
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M. acerifolia Airy Shaw |
New Guinea |
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M. astrolabica Pax & K.Hoffm. |
New Guinea |
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M. bifoveata J.J.Sm. |
New Guinea |
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M. carolinensis Volkens var. carolinensis |
Micronesia |
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M. carolinensis Volkens var. grandifolia Pax & K.Hoffm. |
Micronesia |
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M. dallachyana (Baill.) Airy Shaw |
Australia |
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M. decipiens L.M.Perry |
New Guinea |
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M. densiflora Warb. |
New Guinea |
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New Guinea, Solomon Islands, Santa Cruz, Vanuatu |
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Bismarck Archipelago, Solomon Islands |
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New Guinea |
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New Guinea |
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M. galorei Whitmore |
New Guinea |
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M. hoffmannii L.M.Perry |
New Guinea |
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M. inamoena F.Muell. ex Benth. |
Australia |
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M. involucrata Roxb. ex Baillm |
Sulawesi, Moluccas, New Guinea, Australia, Solomon Islands, Vanuatu |
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M. louisiadum Airy Shaw |
New Guinea |
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M. lugubris Whitmore |
New Guinea |
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M. neobritannica Airy Shaw |
New Guinea |
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M. novoguineensis J.J.Sm. var. novoguineensis |
Moluccas, New Guinea |
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M. novoguineensis J.J.Sm. var. glabra Whitmore |
New Guinea |
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M. punctata K.Schum. var. punctata |
New Guinea |
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M. punctata K.Schum. var. subulata Whitmore |
New Guinea |
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M. rufibarbis Warb. var. rufibarbis |
New Guinea |
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M. rufibarbis Warb. var. campestris Whitmore |
New Guinea |
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M. rufibarbis Warb. var. tenella (Pax & K.Hoffm.) L.M.Perry |
New Guinea |
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M. serratifolia Whitmore |
Sulawesi |
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M. similis Pax & K.Hoffm. |
New Guinea |
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M. strigosa Pax & K.Hoffm. var. strigosa |
New Guinea |
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M. strigosa Pax & K.Hoffm. var. carrii L.M.Perry |
New Guinea |
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M. subpeltata K.Schum. & Lauterb. |
New Guinea |
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M. warburgiana Pax & K.Hoffm. |
New Guinea |
Note — This is the key for the Dioica group and includes the species of Section Pseudorottlera found in New Guinea (viz. M. chlorolepis, M. glaberrima, M. pepysiana). Non Malesian taxa are not hyperlinked to descriptions.
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1a. |
Most (occasionally only) leaves with 3 caudate lobes — New Guinea |
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1b. |
Leaves all or mostly entire |
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2a. |
Stipules much broader than long, acuminate, very closely adpressed to twig, extremely inconspicuous. Fruits with a very dense, uniform covering of very fine 4 mm bristles — New Guinea |
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2b. |
Not so |
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3a. |
Leaves, petioles, twigs and fruits with minute ochreous scales — New Guinea. Section Pseudorottlera |
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3b. |
Tree without ochreous scales |
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4a. |
Leaves with shallowly crenate to deeply serrate margins with dark marginal glands, ovate-elliptic, 5–12 x 1.5–4 cm, base (broadly) cuneate sometimes minutely peltate, apex 2 cm acuminate or caudate, below sometimes ochreous, golden granular glandular — Sulawesi |
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4b. |
Leaves otherwise |
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5a. |
Staminate and pistillate inflorescences 1–3 cm spikes. — Australia (rare Queensland endemic) |
M. dallachyana |
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5b. |
Staminate and pistillate inflorescences longer, often branched |
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6a. |
Stipules linear to subulate to lanceolate, often soon caducous |
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6b. |
Stipules oblong, elliptic to ovate |
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7a. |
Infructescences racemose, peduncle 7 cm, tipped by a single fruit and with 2 opposite branches tipped themselves by 1–3 fruits. Staminate inflorescences 8 cm pubescent spikes with contiguous or grouped flower clusters. Often hermaphrodite. Twigs, petioles and leaves with simple and tufted hairs — Australia (Queensland endemic) |
M. inamoena |
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7b. |
Inflorescences otherwise. Hairs if present all simple |
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8a. |
Leaves with 2 small, sometimes protruding, basal glands (but no glands in plants from Papua), broadest near the base. Staminate flower clusters in loose catkin-like bundles at inflorescence branch tips; bracteoles sharply dentate. Fruits 3 mm, with sparse, sometimes deciduous, 1 mm spines, crowded terminally, subtended by persistent leafy bracts. Infructescence usually simple, occasionally branched — New Guinea |
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8b. |
Leaf base without glands or glands not protruding. Staminate flowers, bracteoles and infructescences otherwise (not known in M. pepysiana). Fruits and infructescences various |
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9a. |
Shrub or treelet to 5 m tall, sarmentose. Fruits red, small, terminal, usually solitary, on a 3–13 cm spike, bilobed, 6 by 9 mm, with short close spines. Staminate panicle only 5 cm long, with erect branches; bracteoles spatulate to trapezoid, thick, spreading, to 1.5 mm long, with several inconspicuous patellar glands inside and sometimes sparsely hairy outside — New Guinea |
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9b. |
Otherwise. Usually a tree |
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10a. |
Leaves small, elliptic, (8–)10(–17.5) by (2–)4(–7) cm, the base cuneate. Fruits solitary, terminating delicate spikes to 6 cm, thickly woody. Seeds smooth, usually drying grey-green. Staminate inflorescences (unknown in M. pepysiana) sinuous spikes, but nearly always malformed as a dense 'witches broom'; clusters few-flowered; bracteoles minute — Section Pseudorottlera |
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10b. |
Otherwise. Leaves often larger. Staminate inflorescence a panicle, never malformed |
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11a. |
Leaves without glands near petiole insertion, drying chocolate brown. Fruits weakly bilobed, 7 mm across, densely spiny, with persistent long styles — New Guinea |
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11b. |
Leaves minutely cordulate at base with 2 glands near petiole insertion, usually drying grey green. Fruits strongly bilobed, 12 mm across, sparsely spiny, styles not seen |
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12a. |
Twigs, petioles and midribs glabrous — Java, Sulawesi, Lesser Sunda Islands, New Guinea |
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12b. |
Twig tips, petioles and midribs shortly pubescent — Java, Lesser Sunda Islands, New Guinea |
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13a. |
Leaves 3 cm peltate, base broadly rounded sometimes with elongate superficial glands between petiole insertion and lower margin — Micronesia |
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13b. |
Leaves otherwise — Malesia, Melanasia or Polynesia |
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14a. |
Leaves 10–16cm long — Micronesia (widespread) |
M. carolinensis var. carolinensis |
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14b. |
Leaves 30 cm long — Micronesia (Ponape) |
M. carolinensis var. grandifolia |
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15a. |
Leaves deltoid, broadest near base, base usually broadly truncate |
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15b. |
Leaves ovate, broadest at or above middle, base usually rounded or cuneate |
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16a. |
Stipules abruptly narrowing to a long filiform tip. Fruits at first with short stout tomentose spines; style simple, 10 mm, lateral with short comb-like hairs along the outer side — New Guinea |
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16b. |
Stipules linear. Fruits at first with short brittle spines; style bifid, 10–15 mm, slightly off-centre, plumose — Sulawesi, Moluccas, New Guinea, Australia |
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17a. |
Staminate plant |
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17b. |
Pistillate plant |
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18a. |
Stamiante bracteoles 3–4 mm across, broadly triangular ovate, 1–5-cusped, without glands, strongly cucullate, densely tomentellose — New Guinea |
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18b. |
Staminate bracteoles smaller, to 2.5 mmm, glabrous or velvety |
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19a. |
Staminate bracteoles entire, usually spreading, with adaxial patellar glands |
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19b. |
Staminate bracteoles lobed or coarsely toothed, concave, without glands |
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20a. |
Leaves elliptic, 8–17 by 3.5–5.5 cm — New Guinea |
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20b. |
Leaves ovate to elliptic, 14–23 by 5–13 cm — New Guinea |
131. M. punctata var. subulata |
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21a. |
Plant pubescent. Lowlands 150(–500) m — Moluccas, New Guinea |
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21b. |
Plant completely glabrous or very sparsely pilose on midrib below. Mountains |
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22a. |
Stipules very soon caducous. Leaves without petiole insertion glands, sparsely pilose on midrib below |
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22b. |
Stipules subpersistent, 10 by 1 mm. Leaves with several small inconspicuous glands near petiole insertion, glabrous — New Guinea |
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23a. |
Fruits to 12 mm, with long, close, fine spines, usually red |
refer back to 21 |
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23b. |
Fruits to 10 mm, usually less, spines short, not red |
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24a. |
Fruits ochre, with short, stiff 0.5 mm conical spines — New Guinea |
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24b. |
Fruits blackish, with soft, sinuous spines, to 2 mm — New Guinea |
131. M. punctata var. subulata |
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25a. |
Pistillate plant (unknown in M. lugubris) |
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25b. |
Staminate plant |
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26a. |
Fruits clustered within persistent leafy bracts |
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26b. |
Bracts soon caducous |
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27a. |
Inflorescence bracts elliptic. Fruits bilobed, 8 mm across, with short spines on apical part, style papillose. Leaves glabrous — New Guinea |
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27b. |
Inflorescence bracts elliptic to ovate. Fruits otherwise and usually uniformly spiny. Leaves tomentose at least below (except dioica var. glabra) |
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28a. |
Stipules very broadly elliptic to triangular, to 10 mm long, base broader than twig. Fruits bilobed, 10 mm across, with coarse, soft, short, hairy spines, style shortly plumose — New Guinea |
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28b. |
Otherwise |
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29a. |
Stipules 15 by 6–8 mm. Fruits maturing glabrous, at first with 3 mm pubescent spines; style 10–15 mm, thread-like, lateral, with comblike hairs on outer side. Leaves acute — New Guinea |
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29b. |
Stipules smaller, 10 by 3–4 mm. Fruits with soft woolly 1mm spines. Style to 10 mm, hirsute, plumose. Leaves often caudate |
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30a. |
All parts variously pubescent — New Guinea, Solomon Islands, Santa Cruz, Vanuatu |
55. M. diocia var. dioica |
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30b. |
Plant entirely glabrous except sometimes for a few hairs on midrib below — New Guinea, Solomon Islands |
55. M. diocia var. glabra |
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31a. |
Fruits with a few short spines. Young twigs strigose |
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31b. |
Fruits closely spiny |
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32a. |
Stipules 8–15 mm long, subpersistent. Leaves not bullate, granular glands below often sparse or absent, base subtruncate sometimes cordulate — New Guinea |
156. M. strigosa var. carrii |
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32b. |
Stipules 4–5 mm long, soon caducous. Leaves finely weakly bullate, black granular glandular below, base broadly truncate, very broadly shallowly cordate, plus at petiole 3 mm cordulate with overlapping or touching lobes — New Guinea |
156. M. strigosa var. strigosa |
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33a. |
Fruit spines coarse, close, rufous. Stipules narrower than twig at base, oblong or elliptic |
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33b. |
Fruit spines fine. Stipules sometimes distinctly broader than twig at base |
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34a. |
Leaves elliptic, 9–17 by 2–6 cm — New Guinea |
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34b. |
Leaves deltoid or elliptic, 7–18 by 4–12cm |
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35a. |
Stipules 5 mm long. Lowlands — New Guinea |
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35b. |
Stipules 10–20 mm long. Mountains |
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36a. |
Stipules oblong, 10 by 2 mm, apex obtuse. Leaves elliptic. A gloomy tree — New Guinea |
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36b. |
Stipules elliptic, 20 by 3 mm, apex acuminate. Leaves deltoid — New Guinea |
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37a. |
Stipules small, 3 by 1.5–2 mm, soon caducous. Infructescence 7–10 cm long. Leaves with margins entire — New Guinea |
131. M. punctata var. punctata |
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37b. |
Stipules larger, at least 10 mm long, (sub)persistent. Infructescence 14–20 cm long. Leaves sometimes crenate |
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38a. |
Stipules 10(–13) by 3–5 mm. Infructescence a spike, to 14 cm. Leaves glabrous below except sparsely hairy near petiole — New Guinea |
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38b. |
Stipules 12–15 x 10 mm. Infructescence 20 cm, a spike or sparsely branched raceme. Leaves pubescent or glabrous below |
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39a. |
Twigs, stipules and petioles furfuraceous. Leaves below with stiff hairs on main nerves, thinly leathery — New Guinea |
57. M. ducis var. ducis |
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39b. |
Glabrous tree. Leaves papery — New Guinea |
57. M. ducis var. glabra |
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40a. |
Lowest inflorescence branches opposite, with axillary branches; bracts oblong, 10 by 2 mm, apex acuminate, usually persistent. Fruits with hairy almost terete spines — New Guinea |
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40b. |
Lowest inflorescence branches without axillary branches, opposite or alternate; bracts otherwise. Fruits with flat almost glabrous spines |
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41a. |
Inflorescence axes rufous tomentose, lowest branches opposite; bracteoles squarish, 5 by 3 mm, irregularly toothed |
refer back to 34 |
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41b. |
Inflorescence axes and bracteoles otherwise |
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42a. |
At least lowest inflorescence branches opposite or subopposite |
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42b. |
Inflorescence branches alternate |
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43a. |
Stipules 15 by 6 mm, often carinate. Leaves intensely velvety. Staminate bracteoles recurved, as long as flower clusters, triangular narrowing above middle 3 by 2 mm, not cucullate, with 2–4 patellar glands inside. (Infructescence bracts 2 by 2 cm. Fruits with 3 mm caducous spines) — New Guinea |
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43b. |
Stipules relatively narrower, 10 by 3–4 mm. Leaves velvety to glabrous. Staminate bracteoles spreading, enclosing flower clusters, ovate, 1.5 by 1.5 mm, apex acute, cucullate, without patellar glands inside. (Infructescence bracts 20 by 5 mm. Fruits with 1 mm persistent spines) |
refer back to 30 |
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44a. |
Inflorescence axes villous; bracteoles 3-lobed; bracts elliptic, 10–25 mm long |
refer back to 32 |
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44b. |
Inflorescence axes pubescent, furfuraceous or glabrous; bracteoles not lobed; bracts otherwise |
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45a. |
Bracteoles deeply distantly dentate — New Guinea |
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45b. |
Bracteole margins entire |
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46a. |
Bracts very soon caducous; bracteoles triangular to oblongate, 2 by 2 mm, variously concave at base — New Guinea |
131. M. punctata var. punctata |
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46b. |
Bracts somewhat persistent; bracteoles otherwise |
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47a. |
Bracts leafy, nerved, elliptic, to 17 by 3 mm, sometimes persistent; bracteoles oblong, 2 by 1 mm, apex acute, spreading or with tip upturned, with 2 adaxial patellar glands — New Guinea |
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47b. |
Bracts variable, triangular to elliptic, 4–8 mm long, 1 mm caudate, subpersistent; bracteoles ovate-trapezoid, 4 by 3 mm, slightly cucullate, erect, without patellar glands |
refer back to 39 |