ALOCASIA NEBULA
ORIGINAL DESCRIPTION:
Alocasia nebula A. Hay, sp. nov. Alocasia scabriuscula N.E.Br. affinis sed stature minore, folii lamina bullata, variegata, lobis posticis ad marginem sinuatis, nervis primariis confertis differt.
Typus: Cult. Hort. Reg. Bot. Sydney, Acc. No. 980858, 30 April 1999, A. Hays.n. (holotype NSW)).
[A. ‘sp. A’ A.Hay, Gard. Bull. Straits Settlem. Singapore 50: 327 (1998)].
[A. guttata var. imperialis sensu hort. (non N.E.Br. =A. scabriuscula N.E.Br.)].
SYNONYMS: Alocasia guttata var. imperialis
DISTRIBUTION: Indonesia | Borneo | Likely Sarawak
CLIMATE: Tropical humid climate
Humidity is moderate throughout the year, ranging from 60% to 70%
Temperature is varies between the seasons - within the range of 48°F/9°C to 88°F/31°C during the day. Minimum temperatures never dip below 45°F/7°C
Rainy and humid season (October to May) and a dry season between June and October. The average annual rainfall is 1,200 mm
ECOLOGY: Thought to be from rain-forest floor over limestone at low elevation.
SPECIES DESCRIPTION:
Herb about 20-30 cm tall; stem c. 2.5 cm diam. Leaves c. 6 together, glabrous, peltate in quite advanced juveniles but not in adult plants; petiole c. 15 cm long, dull pale green spotted with mostly transversely orientated elliptic minute deep purple dots and larger, slightly raised glands of the same color, sheathing in the lower 1/4 - 1/3; wings of sheath at first clasping younger leaf bases, later widely flared, persistent, tinged red marginally; blade ovato-sagittate, held pendent to obliquely erect, strongly coriaceous but not markedly thick, bullate between the costae, primary and subsidiary veins (thicker-than-normal secondary veins), adaxially matt grey green, darker about the costae and main veins and over the subsidiary and submarginal veins, abaxially dark reddish purple; anterior lobe c. 15 cm long and wide, with the widest part a few cm distal to the petiole insertion, the tip obtuse and apiculate for c. 2 mm; primary lateral veins 5-7 on each side of anterior costa, the proximal ones close-spaced, diverging at c. 90° (proximal ones) to 45° (distal ones), impressed adaxially, dark purple and bearing conspicuous axillary glands abaxially; secondary veins adaxially impressed, mostly obscure abaxially; subsidiary veins frequent, 1~2(—3) on each side of primary veins in the outer third of the lamina, adaxially impressed and abaxially conspicuously colored, and, with the secondary veins, forming distinct interprimary collective veins; primary and interprimary collective veins running into a conspicuous submarginal vein c. 2 mm within the margin; posterior lobes acute, c. 8—9 cm long, with the outer margins slightly sinuate, the inner sides narrowly lanceolate; posterior costae diverging at 45-60°, naked in the sinus for c. 1.5 cm
INFLORESCENCE:
Inflorescences c. 4 together, smelling sweetly of citrus apparently from the lower part of the spadix; subtending cataphylls at first colored like the petiole, then marcescent, exceeding the peduncle and lower spathe; peduncle short, completely concealed by leaf and cataphyll bases. Spathe c. 6 cm long; lower part of spathe ovoid, 2.5 cm long, ivory, dotted deep purple; spathe limb oblong-lanceolate, abaxially colored like the lower spathe, unmarked within, the margin purple, at first erect-cucullate, then reflexed. Spadix somewhat shorter than the spathe, c. 5 cm long, sessile; female zone 1 cm long, c. 8 mm wide; ovaries ovoid, pale green; style c. 1 mm long, not abruptly differentiated from ovary, slightly ascending; stigmas ivory-white with 2-3 drop-shaped lobes; sterile interstice 4 mm long, somewhat attenuate and lax basally, c. 4 irregular whorls of synandrodia, the lower ones reduced, the upper ones resembling sterile synandria; male zone ivory, 1.2 cm long, c. 5 mm diam., c. half within the lower spathe chamber, the rest exserted; synandria rhombo-hexagonal, c. 2 mm diam., the thecae not overtopped by synconnective; appendix buff, c. 2 cm long, c. 5mm diam., distally tapering, somewhat constricted at junction with male zone. Fruit unknown.
VARIEGATED FORMS: WHITE
ETYMOLOGY: The specific epithet, a noun in apposition, means vapor, mist, smoke, and alludes both to the plant’s origin, clouded in uncertainty, and to the soft variegation pattern on the leaves.
NOTES: The inflorescence of Alocasia nebula, though somewhat smaller, is virtually identical to that of Alocasia scabriuscula. The two species are clearly differentiated in the leaf, which is significantly smaller than that of Alocasia scabriuscula, thinner textured though strongly coriaceous, variegated, bullate, with a pronounced submarginal vein, and a large number of primary lateral veins for the size of the leaf - these arranged in a distinctive clustered pattern in the proximal part of the blade.
While the precise origin of Alocasia nebula is uncertain, it is thought to be from limestone at Semenggoh, near Kuching in Sarawak (P.C. Boyce). Peter Boyce, Josef Bogner and independently Alistair Hay all observed it growing there in the mid-1990s. Alocasia nebula is still unknown in the wild.
Alocasia nebula is a lowland tropical plant and requires correspondingly warm temperatures. In collections in tropical Queensland, it evidently flourishes best in areas of very high rainfall and humidity and requires shade to avoid bleaching or scorching by the sun. Other than the swamp-dwelling species, Alocasia generally do best in an open mix incorporating a large amount of organic matter and coarse sand. They seem to benefit from a wide root run. Limestone species respond well to the addition of coarsely crushed dolomite — powdered dolomite leaches too quickly in the heavy watering regime that is required during active growth. Well-grown plants frequently produce cormels on slender stolons at or below soil level. These often have a protracted dormancy, but can be used to keep the plants going as the adults are prone to sudden collapse, especially if the roots become too cool and waterlogged.
CULTIVARS: N/A (no cultivars are recognized, though despite that, sellers may try to sell plants as Alocasia nebula ‘Elaine’ or Alocasia nebula ‘Imperialis’ but they are all Alocasia nebula)
REFERENCES:
Variegated Alocasia nebula by @alltheplantys
