Key to Bornean Alocasia Species


Based on Boyce, 2007

Click on 📌 to highlight and compare characteristics.
Click on the line numbers to select characteristics.



1A. Leaf blades not peltatePeltate: in adult plants .. 2
2A. Secondary venationVenation: The arrangement of veins in the leaf. distinctly prominent abaxialAbaxial: Facing away from the stem of a plant (especially denoting the lower surface of a leaf). ly and forming welldefined interprimary collective veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s .. 📌Alocasia sarawakensis
2B. Secondary venationVenation: The arrangement of veins in the leaf. not prominent abaxialAbaxial: Facing away from the stem of a plant (especially denoting the lower surface of a leaf). ly, or, if prominent, then not forming well-defined interprimary collective veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s .. 3
3A. Leaf blade membranous, often immense, abaxialAbaxial: Facing away from the stem of a plant (especially denoting the lower surface of a leaf). ly waxy-glaucousGlaucous: Covered with a whitish powder or waxy coating. .. 📌Alocasia robusta
3B. Leaf blade of various sizes and textures, not waxy-glaucousGlaucous: Covered with a whitish powder or waxy coating. (though sometimes abaxialAbaxial: Facing away from the stem of a plant (especially denoting the lower surface of a leaf). ly grey-green) .. 4
4A. Male zone of spadixSpadix: A spike of minute flowers closely arranged around a fleshy axis and typically enclosed in a spathe. completely exerted from lower spatheSpathe: A large sheathing bract enclosing the flower cluster. chamber (always in association with human disturbance) .. 📌Alocasia macrorrhizos
4B. Male zone of spadixSpadix: A spike of minute flowers closely arranged around a fleshy axis and typically enclosed in a spathe. partly or wholly within lower spatheSpathe: A large sheathing bract enclosing the flower cluster. chamber (plants of natural forested habitats) .. 5
5A. Leaf blade narrowly to broadly ovato-sagittateSagittate: , nearly always stiffly leathery to subsucculent .. 6
6A. Adaxial leaf blade grey-green and distinctly dark green about main veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s .. 7
7A. AbaxialAbaxial: Facing away from the stem of a plant (especially denoting the lower surface of a leaf). leaf blade purple; anteriorAnterior: costa with c. 6 primary lateral veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s on each side, with conspicuous subsidiary veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s (geology & origin unknown) .. 📌Alocasia nebula
7B. AbaxialAbaxial: Facing away from the stem of a plant (especially denoting the lower surface of a leaf). leaf blade not purple; anteriorAnterior: costa with 2--3 primary lateral veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s on each side; subsidiary veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s absent (limestones: SE Sarawak) .. 📌Alocasia reversa
6B. Adaxial leaf blade of various colours but not variegated .. 8
8A. Inflorescence pairs solitary and secondary venationVenation: The arrangement of veins in the leaf. adaxially impressed (limestones: Mulu) .. 📌Alocasia reginae
8B. Inflorescence pairs clustered or if solitary then secondary venationVenation: The arrangement of veins in the leaf. not impressed .. 9
9A. PosteriorPosterior: lobes ca 1/2 or more the length of the anteriorAnterior: ; blade stiffly leathery (lithophytic on or terrestrial in close association with limestone (limestones: SE Sarawak) .. 📌Alocasia ridleyi
9B. PosteriorPosterior: lobes less than to ca 1/2 the length of the anteriorAnterior: ; blade thickly coriaceousCoriaceous: Resembling or having the texture of leather. to subsucculent; terrestrial and not especially associated with limestone (widespread in Borneo) .. 📌Alocasia scabriuscula
5B. Leaf blade hastato-sagittateSagittate: , triangular in outline, mostly rather thinly leathery .. 10
10A. Plants terrestrial, not limestone associated .. 11
11A. PetiolePetiole: Leaf stem. s mottled with wavy oblique zones of dense brown lines, occasionally scabrid; spatheSpathe: A large sheathing bract enclosing the flower cluster. s mostly dusky brownish mauve, the limb darker; lower spatheSpathe: A large sheathing bract enclosing the flower cluster. narrowly ovoid; limb mostly narrowly lanceolateLanceolate: (Sabah) .. 📌Alocasia wongii
11B. PetiolePetiole: Leaf stem. s variously and more or less haphazardly marked with lines and/or dots, smooth or occasionally faintly bumpy (glands), but not scabrid; spatheSpathe: A large sheathing bract enclosing the flower cluster. s mostly ivory to yellowish ivory, variously marked or not with pink to purple, and/or purple-margined; lower spatheSpathe: A large sheathing bract enclosing the flower cluster. broadly ovoid; limb more or less oblongOblong: (widespread in Borneo) .. 📌Alocasia princeps
10B. Plants lithophytic on limestone .. 12
12A. Male zone of spadixSpadix: A spike of minute flowers closely arranged around a fleshy axis and typically enclosed in a spathe. completely within lower spatheSpathe: A large sheathing bract enclosing the flower cluster. chamber; leaf blades distinctly grey-green adaxially (limestones: Sabah, E. Kalimantan) .. 📌Alocasia principiculus
12B. Male zone of spadixSpadix: A spike of minute flowers closely arranged around a fleshy axis and typically enclosed in a spathe. partly exsertedExserted: Protruded, stretched out, or (esp of stamens) projecting. from lower spatheSpathe: A large sheathing bract enclosing the flower cluster. chamber; leaf blades dark to bright green adaxially (Sabah) .. 13
13A. Leaf blade bright green adaxially; inner side of posteriorPosterior: lobe ovateOvate: ; male zone more or less adjunct to female zone or interstice short, not attenuate, formed of 1-2 whorls of synandrodia, resembling synandriaSynandria: Sets of stamens of which the anthers have been fused. (limestones: Gua Madai) .. 📌Alocasia puteri
13B. Leaf blade dark green adaxially; inner side of posteriorPosterior: lobe ellipticElliptic: to narrowly ovateOvate: ; interstice elongate, partly naked, with neuter organs resembling staminodeStaminode: A sterile or abortive stamen, frequently resembling a stamen without its anther. s below and resembling synandriaSynandria: Sets of stamens of which the anthers have been fused. above (limestones: Gua Madai) .. 📌Alocasia pangeran
1B. Leaf blades distinctly (shallowly to completely) peltatePeltate: in adult plants .. 14
14A. Leaf blades + membranous and pendent, often solitary or only 2-3 together, often adaxially dark green with whitish major veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s (sometimes adaxially concolorous), often purple-backed, shallowly to deeply peltatePeltate: ; stigmaStigma: The receptive tip of a carpel, or of several fused carpels, in the gynoecium of a flower. stellate with pointed lobes; interstice corresponding with spatheSpathe: A large sheathing bract enclosing the flower cluster. constriction and male zone completely exerted .. 📌Alocasia longiloba complex (see Hay, 1998)
14B. Leaf blades variously coriaceousCoriaceous: Resembling or having the texture of leather. , pendent or not, few to several together, deeply to almost completely peltatePeltate: ; stigmaStigma: The receptive tip of a carpel, or of several fused carpels, in the gynoecium of a flower. not lobed or lobes rounded; interstice and part or all of male zone within lower spatheSpathe: A large sheathing bract enclosing the flower cluster. cham .. 15
15A. Leaf blades metallic greenish brown adaxially, bullate between primary veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s; lower primary veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s diverging at first at more than 90 (Sabah & NE Sarawak) .. 📌Alocasia cuprea
15B. Not this combination .. 16
16A. Adaxial leaf surface strongly and minutely rugoseRugose: Wrinkled; corrugated. with the tertiary venationVenation: The arrangement of veins in the leaf. raised (ultramafics: Sabah) .. 📌Alocasia melo
16B. Adaxial leaf surface smooth or with secondary venationVenation: The arrangement of veins in the leaf. impressed .. 17
17A. Adaxial leaf laminaLamina: Leaf blade. e very dark black-green with white impressed primary and secondary venationVenation: The arrangement of veins in the leaf. ; spadixSpadix: A spike of minute flowers closely arranged around a fleshy axis and typically enclosed in a spathe. with appendixAppendix: Sterile appendage at the end of a spadix. reduced (limestone: Bukit Tabin) .. 📌Alocasia reginula
17B. Adaxial leaf laminaLamina: Leaf blade. e not variegated, or if variegated then main veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s and neighbouring blade darker than the rest; appendixAppendix: Sterile appendage at the end of a spadix. well developed .. 18
18A. Leaf blades with conspicuous intramarginal veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. and marginal veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. ; laminaLamina: Leaf blade. e broadly to narrowly ellipticElliptic: , with the base cuneateCuneate: ; male zone wholly within the lower spatheSpathe: A large sheathing bract enclosing the flower cluster. (above 800 m, Borneo) .. 📌Alocasia peltata
18B. Leaf blades with more or less conspicuous marginal veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. only; laminaLamina: Leaf blade. e various; male zone wholly or partly within the lower spatheSpathe: A large sheathing bract enclosing the flower cluster. (mostly below 500m, Borneo) .. 19
19A. Primary lateral veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s numerous, 8-10 on each side of midrib; secondary venationVenation: The arrangement of veins in the leaf. striate; in peat swamp forest (peat swamp forest: Sarawak) .. 📌Alocasia minuscula
19B. Primary lateral veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s much fewer; secondary venationVenation: The arrangement of veins in the leaf. clearly colocasioid, but not forming interprimary collective veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s .. 20
20A. Leaf blades thickly coriaceousCoriaceous: Resembling or having the texture of leather. to subsucculent; male zone of spadixSpadix: A spike of minute flowers closely arranged around a fleshy axis and typically enclosed in a spathe. within lower spatheSpathe: A large sheathing bract enclosing the flower cluster. chamber .. 21
21A. Leaf laminaLamina: Leaf blade. e broadly ovato-ellipticElliptic: , adaxially pale matt grey, abaxialAbaxial: Facing away from the stem of a plant (especially denoting the lower surface of a leaf). ly greenish white with conspicuous deep red axillary glands abaxialAbaxial: Facing away from the stem of a plant (especially denoting the lower surface of a leaf). ly; petiolePetiole: Leaf stem. s puberulentPuberulent: Covered in soft, downy hairs. ; fruiting spatheSpathe: A large sheathing bract enclosing the flower cluster. magenta (Kapit, evergreen upper hill forest on sandstones above 500 m asl) .. 📌Alocasia chaii
21B. Leaf blade narrowly ellipticElliptic: to ovateOvate: to narrowly obovateOvate: , mid green above, slightly paler with inconspicuous pale green axillary glands; petiolePetiole: Leaf stem. s glabrousGlabrous: Smooth. Free from hair or down. fruiting spatheSpathe: A large sheathing bract enclosing the flower cluster. pale green (NW Borneo, kerangas below 500 m) .. 📌Alocasia beccarii
20B. Leaf blades thinly coriaceousCoriaceous: Resembling or having the texture of leather. or sub-membranous; male zone only partly included within the lower spatheSpathe: A large sheathing bract enclosing the flower cluster. chamber .. 22
22A. LaminaLamina: Leaf blade. e ascending (adult plants) to weakly spreading (juveniles), thinly and weakly coriaceousCoriaceous: Resembling or having the texture of leather. , lustrous deep purple-black; petiolePetiole: Leaf stem. s minutely puberulentPuberulent: Covered in soft, downy hairs. ; infructescences deflexed (Kapit: sandstones) .. 📌Alocasia infernalis
22B. LaminaLamina: Leaf blade. e pendent to weakly spreading (adult & juvenile plants), thinly, stiffly coriaceousCoriaceous: Resembling or having the texture of leather. ; never deep purple-black; petiolePetiole: Leaf stem. s glabrousGlabrous: Smooth. Free from hair or down. ; infructescences erect (limestones) .. 23
23A. Leaf blades dark green throughout and somewhat darker around midveinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s; inflorescences to ca 6 together; stigmaStigma: The receptive tip of a carpel, or of several fused carpels, in the gynoecium of a flower. mostly tri-lobed (limestones: Gua Niah) .. 📌Alocasia venusta
23B. Leaf blades grey-green and dark blue-green around veinVein: Venation types: A. midrib; B. primary lateral veins; C. interprimaray veins; D. secondary veins; E. collective veins; F. tertiary veins; G. basal ribs; H. basal veins. s; inflorescences solitary to paired; stigmaStigma: The receptive tip of a carpel, or of several fused carpels, in the gynoecium of a flower. mostly bi-lobed (limestones: SE Sarawak) .. 📌Alocasia reversa
 


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