THAI FOR. BULL. (BOT.) 36: 1–17. 2008.
A review of Alocasia (Araceae: Colocasieae) for Thailand including a novel species and new species records from South-West Thailand
PETER C. BOYCE*
ABSTRACT. A review of Alocasia in Thailand is presented. One new species (A. hypoleuca) and three new records (A. acuminata, A. hypnosa & A. perakensis) are reported. A key to Alocasia in Thailand is presented and the new species is illustrated.
Alocasia is a genus of in excess of 100 species of herbaceous, laticiferous, diminutive to gigantic, usually robust herbs. The genus has recently been revised for New Guinea (Hay, 1990), Australasia (Hay & Wise, 1991), West Malesia and Sulawesi (Hay, 1998), the Philippines (Hay, 1999) while post main-treatment novelties have been described for New Guinea (Hay, 1994) Borneo (Hay, Boyce & Wong, 1997; Hay, 2000; Boyce, 2007) & Sulawesi (Yuzammi & Hay, 1998). Currently the genus is least well understood in the trans-Himalaya (NE India to SW China) including the northern parts of Burma, Thailand, Lao PDR and Vietnam with only the flora of Bhutan (Noltie, 1994) partly covering this range. In the absence of extensive fieldwork the account presented here for Thailand can at best be regarded as provisional.
STRUCTURE & TERMINOLOGY
Alocasia plants are often complex in vegetative and floral structure and some notes on their morphology (based here substantially on Hay, 1998) are useful to aid identification.
The stem of Alocasia, typically of mostAraceae, is a physiognomically unbranched sympodium. The number of foliage leaves per module is variable between and within species and individuals, but during flowering episodes in some species it may be reduced to one. In some species, e.g. A. peltata M.Hotta (Borneo), foliage leaves alternate with cataphylls within a module. In such instances the cataphyll performs the role of protecting the subsequent emerging leaf. That role in other species is performed by the sheath of the previous foliage leaf. Those species with regularly interspersed cataphylls typically have very short leaf sheaths, while those without interspersed cataphylls have longer sheaths. A prophyll and usually at least one cataphyll is always associated with the initiation of a new vegetative module.
Permanent address: Lot 12, Taman Hillsdale, Mile 10S Jalan Kuching Serian, Padawan, Kuching,