ALOCASIA CHAII
ORIGINAL DESCRIPTION:
Ab Alocasia scabriscula sed stature valde parviore,folii lamina peltato etspathae fructiferorum extus in toto magenteus vividus diff ert
TYPUS: Sarawak, Kapit
Gard. Bull. Singapore 58: 142 (2007)
SYNONYMS: N/A
DISTRIBUTION: Indonesia | Borneo | Sarawak (Known only from Kapit Division, in the foothills of Gunung Bukit Batu, Hose Mountains and Ulu Kapit)
CLIMATE: Subtropical 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: Steep to precipitous leaf litter-covered red clay-loam slopes beneath open to rather dense canopy of moist upper hill forest in light to moderate shade, 540-760 m asl.
SPECIES DESCRIPTION:
Small robust herb to ca 40 cm tall, stem shortly erect to decumbent, eventually forming a short rhizome; wild plants with rather few leaves (up to 4, usually less), cultivated plants with several leaves (up to 7); petioles stout, ca 20 cm long, sheathing in the lower ca 1/4, puberulent, pale green with scattered
deep red spots and speckles in the lower half; sheath persistent, ± closed; lamina broadly ovato-elliptic, up to 40 cm long but frequently much less and typically reaching c. 23 cm x 10-15, exceptionally up to 25 cm wide, thickly coriaceous to subsucculent, almost completely peltate save for a shallow retuse notch between the tips of the connate posterior lobes, margins reflexed to form a raised smooth rim abaxially, apex acute to obtuse and mucronate for ca 1 cm, lamina adaxially pale matt grey, abaxially greenish
white, anterior costa with 1-3 primary lateral veins on each side, diverging at ca 90° (proximal ones) to 30° (distal ones); primary veins adaxially somewhat raised proximally to the mid-rib and impressed distally, flush to very slightly impressed with deep red axillary glands abaxially; secondary venation impressed adaxially, more or less flush with the lamina abaxially, forming defined interprimary collective veins when fresh, this decidedly obscure in dried material; posterior lobes about 1/3 - 1/4 the length of the anterior, with the posterior costae diverging at ca 30°
INFLORESCENCE:
Inflorescences several together (up to 4 on vigorous plants), each subtended by a short, broad prophyll and a single cataphyll; peduncle short, more or less hidden within cataphyll; spathe ca 7 cm long, externally white with a scattered red flecks on the lower part, interior uniformly glossy white; lower spathe 2.5-3.5 cm long, ovoid, separated from limb by a rather weak oblique constriction; limb erect even after anthesis, narrowly lanceolate-triangular, 3-5 cm long; spadix ca 2/3 the length of the spathe, ca 4.5 cm long, briefly stipitate; stipe cylindrical, ca 2-5 mm tall, glossy white; female zone about 1/4 of the length of the spadix, pistils moderately densely arranged; ovaries ovoid, ca 1.5 mm diam., facing diagonally up, pale greenish white; style ± absent; stigma white, single, bilobed, sometimes trilobed (all variations present in a single inflorescence); sterile interstice absent or represented by a few (less than 5) synandrodia; male zone held entirely within the lower spathe, cylindric to barrel-shaped, about 1/4 the length of the spadix, about 2/5 as wide as long, ivory; synandria densely arranged, more or less square in plan view, ca 1.5 mm wide, the thecae very slightly overtopped by synconnective; appendix about 1/3 of the length of the spadix, narrowly conic; fruiting spathe broadly ovoid, c. 2.5 cm long, erect, glossy brilliant magenta with a few scattered darker spots and streaks at fruit maturation, then 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, ca 3mm diam., pace brown.
VARIEGATED FORMS: N/A
ETYMOLOGY: Alocasia chaii is named for Dr Paul P.K. Chai former Forest Botanist, now with ITTO, Forest Department, Sarawak.
NOTES: Alocasia chaii belongs to the informal Alocasia scabriscula group (see Hay, 1998), notable for coriaceous, leathery to subsucculent leaves and the spathe usually constricted at a level above the sterile interstice of the spadix, thus, including the all or at least the majority of male flower zone within the lower spathe. Alocasia chaii is most similar to Alocasia scabriscula N.E.Br, in overall morphology, differing in the considerably smaller, but hardly less robust habit, the peltate leaves and the persistent lower spathe
that turns bright magenta at fruiting. In general stature and by the grey leaves Alocasia chaii also vaguely resembles Sabahan Alocasia melo A.Hay, P.C.Boyce & K.M.Wong, although the latter is readily distinguished by the rugose and bullate adaxial lamina surface and the fruiting spathe white with slight red speckling. Alocasia melo is confined to ultramafic substrates. There appear to be two closely allied species involved here, one in the lowlands (up to 150 m asl) that has not as yet found fertile, and a higher elevation element (occurring above 500 m asl), here described as Alocasia chaii. Aside from the altitudinal differences noted, the lowland element has the leaves proportionately longer than broad (ovato-triangular in outline), lacks the deep red abaxial leaf glands (glands concolorous with the abaxial lamina surface in the lowland element), and is overall a less robust plant occurring in open habitats. The occurrence of related attitudinally differentiated/morphologically distinct taxa has been noted elsewhere in Alocasia, as for example, Alocasia beccarii Engl, (lowland) & Alocasia peltata M.Hotta (highland).
Other specimens examined: SARAWAK: Kapit Division: Pergunungan Hose, foothills below Bukit Batu, 02° 14' 47.2"; 113° 41' 24.9", 23 April 2004, P.C.Boyce & Jeland ak Kisai AL-51 (SAR); Ulu Kapit, Sungai Nai, near Punan Bah, 23 Sept. 1973, P.Chai et al. S.33339 (SAR); Pergunungan Hose,Ulu Sungai Temiai, 5 July 2003, C.Lee et al., S87433 (SAR).
Alocasia chaii and A. infernalis were among those species the subject of a joint tissue culture project between Malesiana Tropicals and UNIMAS funded under MOSTIIGS (IGS R&D Proj. No. 16/03), together with a further 14 Sarawakian Alocasia species and representatives of several other aroid genera that are now in Sarawak Forestry Department licensed commercial tissue culture production in Kuching laboratory of Malesiana Tropicals
CULTIVARS: N/A
HYBRIDS: N/A
