Although Hapaline is entirely palaeotropical in distribution, its morphology, cytology, anatomy and biochemistry indicate a close relationship to neotropical genera. Grayum (1984, 1990) cited seven characters that separate Hapaline from other palaeotropical ëcolocasioid‰ genera (e.g. Ariopsis Nimmo, Remusatia Schott and Colocasia Schott) (Table 1). Some of these characters are now know to occur sporadically in other paleotropical genera (Hay pers. comm.) but nowhere except Hapaline do all occur as a suite. Grayum‰s second character (Absence of sympodial branching in the terminal reproductive shoot) is unreliable and should be deleted from the list; synflorescences do occur in Hapaline. French & Tomlinson (1983) and Fox & French (1988) demonstrated that the permanent cortical vascular system typical of neotropical ëcolocasioids‰ (excluding Jasarum Bunting) and absent from palaeotropical genera, is present in Hapaline. Further evidence of a neotropical link was presented by French & Fox (in prep.) who found that the white latex secreted from cut tissue of Hapaline is similar in composition to that found in neotropical Caladieae and unlike that of palaeotropical genera in the Colocasieae. Palynological evidence for an alliance between Hapaline and neotropical genera is less convincing. Hapaline pollen has spinose exine sculpturing, a character shared by almost all other palaeotropical colocasioids‰ (except Steudnera Schott and some Colocasia spp.), but occurring only in neotropical Syngonium (Grayum 1984, 1990, 1992). However, Grayum (1984) noted that the trinucleate pollen of Hapaline was similar only to Remusatia among the palaeotropical colocasioid‰ genera. An interesting hypothesis put forward by Grayum (1984) was that Hapaline might be related to Pinellia Tenore in tribe Areae (subfamily Aroideae sensu Grayum 1984 (= subfamily Aroideae: tribe Arisaemateae sensu Mayo, Bogner & Boyce, in press)). This is based on the shared characters of tuberous habit, fusion of the base of the spathe and spadix, sterile male flowers or naked regions above and below the fertile male flowers, unilocular, uniovular ovaries, anatropous ovules, endospermous seeds, inaperturate, globose, spinose, starchy, trinucleate pollen and a base chromosome number of x = 13. However, Hapaline and Pinellia differ in a number of fundamental characters, including venation (ëcolocasioid‰ versus reticulate), stamen type (synandria versus free) and secretion tubes (present versus absent). Grayum concluded that although it was conceivable that Hapaline might be moved to tribe Areae, for the time being it was best left in subfamily Colocasioideae (all sensu Grayum 1984).