NEW RECORDS OF THREE AROIDS FROM BANGLADESH

Three species of Araceae viz. Colocasia oresbia A. Hay, Rhaphidophora grandis Schott and R. pertusa (Roxb.) Schott are recorded here for the first time from Bangladesh. Correct names with important synonyms, illustrated description, flowering and fruiting times, ecology, geographical distribution and occurrence within Bangladesh for each species are provided.


Introduction
The family Araceae, consisting of about 110 genera and 2500 species (Croat 1979), is mostly distributed in the tropics and subtropics of both the hemispheres.Bangladesh, having humid tropical climate in the S. Asia, is also rich in aroids.
The illustrated taxonomic descriptions of the three species along with their local distribution are given below.Updated nomenclature, important synonyms, notes on ecology, geographical distribution and the occurrence of each species in Bangladesh are also provided.

Materials and Methods
The plant materials have been collected from different areas of greater Chittagong Hill-Tracts and Maulvi Bazar districts during several field trips between 1998 and 2003.All the specimens are kept in the Bangladesh National Herbarium (DACB) after the study.The specimens have been identified with the help of Nicolson (1987), Karthikeyan (1989), Noltie (1994) and Hay (1996).A. Hay, Sandakania 7: 31-48 (1996).
Note: Four species of Colocasia, previously reported from Bangladesh territory (Ara 2000, 2001and Ara et al. 2003), are C. affinis, C. esculenta, C. fallax and C. heterochroma.C. oresbia is different from the above mentioned four species and it can easily be identified by its non-waxy, wettable leaf blades, rather long stout stem thickly clothed in old leaf bases, lack of stolons, much more robust infructescence, straight fruiting peduncle and montane plants.( Fig. 2)
Note: Rhaphidophora grandis Schott closely resembles R. glauca Schott but differs by its leaf blade over 40 cm and pinnately cut, not glaucous beneath, pinnae up to 6-12 per side and spadix over 13 cm long.
Ecology : Grows on trees in wet lowland forest.Distribution: Southern India, Sri Lanka, Southern Mexico to West Indies and Southern Brazil.
Note : Six species of Rhaphidophora, previously reported from Bangladesh (Ara 2001 andUddin et al. 2001), are R. affinis, R. calophyllum, R. decursiva, R. glauca, R. hookeri and R. hongkongensis.R. pertusa differs from all the above mentioned six species and it can easily be separated by its leaves entire or only shallowly or irregularly pinnatifid, occasionally with large holes and stigma sessile, not stalked.