Alocasia infernalis P.C.Boyce

First published in Gard. Bull. Singapore 58: 145 (2007)
This species is accepted
The native range of this species is Borneo (Sarawak). It is a perennial or subshrub and grows primarily in the wet tropical biome.

Descriptions

CATE Araceae, 17 Dec 2011. araceae.e-monocot.org

Diagnostic
Alocasia infernalis belongs to the Alocasia scabriscula group (see Hay, 1998) by virtue of the pubescent petioles and the positioning of the
spathe constriction above the base of the male zone of the spadix such that all or at least the basal part of the male zone is held within the lower spathe chamber. However, it is not at all apparent to which other species in the group A. infernalis is most closely allied since by the leaf texture and deflexing infructescences it is unique in the group. In overall appearance (leaves rather membranous more-or-less completely peltate, spadix distinctly shorter than the spathe) it is superficially similar to species in the Alocasia cuprea (C.Koch & Bouché) C.Koch group but is readily distinguished by the leaves not  interspersed with cataphylls.
The metallic-purple leaves of the seedlings and juvenile plants is remarkable while the lustrous deep purple-black of the ascending leaves of mature plants, coupled with the dwarf habit, is unmatched by any other species. Alocasia infernalis is perhaps the most horticulturally significant species of Bornean Alocasia yet discovered.
General Description

Small robust herb to ca 55 cm tall, stem slender, erect to ultimately decumbent with the active shoot tip ascending; leaves several together in nature, in cultivation up to 12, spreading in juveniles but erect in adult plants; petioles slender, spreading to ascending, ca 20 cm long, sheathing in the lower ca ½, minutely puberulent (lens required), bronze-green to purple-green depending on exposure, stronger light inducing a weak snake-skin marking, particularly on the interior of the sheath; sheath fleshy-membranous, open and recurving in the lower part; lamina ovato-triangular, up to 25 cm long but frequently much less and typically reaching ca 15 cm x 10−12 cm, thinly and somewhat weakly coriaceous, juveniles almost completely peltate except for a shallow retuse notch between the tips of the connate posterior lobes, adult leaves strongly peltate but with a 1−2 cm deep notch in the sinal tissue, margins smooth, apex acute, acuminate for ca 1 cm, adaxially glossy, very deep purple, abaxially deep purple, anterior costa with ca 3 primary lateral veins on each side, diverging at ca 60° (proximal ones) to 45° (distal ones); primary veins impressed distally adaxially, prominently raised abaxially; secondary venation obscure adaxially, abaxially forming strongly defined and raised interprimary collective veins; all veins running to a prominently raised (abaxially) inframarginal collecting vein; posterior lobes about ¼ the length of the anterior, posterior costae diverging at ca. 20°. Inflorescences 2 together, each subtended by a short, broad prophyll and a single cataphyll; peduncle long, ca 4−6 cm, pale green or purple flushed; spathe 4−9.5 cm long, lower spathe pale green, spathe limb externally glossy purple with the margins pale green; lower spathe 1.5−2.5 cm long, ovoid, separated from limb by a moderate constriction; limb narrowly lanceolate-triangular, at first erect then soon strongly reflexing and twisting with the margins inrolled, 2−6.5 cm long; spadix ca 1/2 the length of the spathe, ca 4.5 cm long, very briefly stipitate; stipe umbonate, ca 2 mm tall, glossy white; female zone ca 1/3 of the length of the spadix, pistils moderately densely arranged; ovaries compressed-globose, ca 2 mm diam., facing diagonally up, pale greenish white; style absent; stigma white, mostly trilobed, sterile interstice with a few scattered, compressed white synandrodia; male zone partially held within the lower spathe, cylindric, ca 1/3 the length  of the spadix, ivory; synandria somewhat laxly arranged, transversely oblong in plan view, ca 2 x 1 mm, thecae extending slightly from the edge of the synconnective; appendix about 1/3 of the length of the spadix, narrowly conic, pointed, white; fruiting spathe broadly ovoid, ca 2.5 cm long, pendent by reflexing of the peduncle, dull mid-green at fruit maturation, splitting longitudinally into several unequal strips, these reflexing to reveal the ripe berries; berries bright orange to red, globose, ca 0.5 cm diam., each with 1−3 seeds; seeds compressed ovoid, ca 2.5 diam., medium brown.

Habitat
Valley bottoms in moist to ever-wet lowland forest on deeply leaf litter-covered red sandstone-derived clay-loams in heavy shade
Distribution
Sarawak, Kapit Division. To date known only from the Sungai Gaat watershed.
[CATE]

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation
Predicted extinction risk: threatened. Confidence: confident
[AERP]

Sources

  • Angiosperm Extinction Risk Predictions v1

    • Angiosperm Threat Predictions
    • http://creativecommons.org/licenses/by/4.0
  • CATE Araceae

    • Haigh, A., Clark, B., Reynolds, L., Mayo, S.J., Croat, T.B., Lay, L., Boyce, P.C., Mora, M., Bogner, J., Sellaro, M., Wong, S.Y., Kostelac, C., Grayum, M.H., Keating, R.C., Ruckert, G., Naylor, M.F. and Hay, A., CATE Araceae, 17 Dec 2011.
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0
  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0
  • Kew Science Photographs

    • Copyright applied to individual images