MORPHOLOGY AND DISTRIBUTION

Habit and stem All species of Hapaline are diminutive to moderate-sized slender to slightly robust tuberous or stoloniferous, clump-forming terrestrial herbs. Tuberous-stemmed species often produce slender, cataphyll-encased stolons that eventually give rise to new tubers.

Leaf

Leaf blades in Hapaline are either thin-textured or thick and leathery. They vary in shape from ovate to hastate. Posterior lobes are present in all species, although lacking from some individuals of H. appendiculata Ridl. (see below). The arrangement of the posterior lobes ranges from being parallel in Hapaline ellipticifolia C.Y. Wu & H. Li, resulting in an elliptic leaf blade, to hastate in H. colaniae Gagnep. Hapaline displays two distinct growth types which are linked to the thickness of the leaf blades. Species with thin-textured leaf blades (i.e. H. benthamiana, H. brownii, H. colaniae, H. ellipticifolia and H. kerrii) undergo an annual dormant period. These species occur in areas with a seasonal climate (e.g. Burma, central and NE Thailand, northern Peninsular Malaysia, much of Vietnam). New growth is marked by leaf emergence and abundant flowering. Species with thicker, leathery leaves, (H. appendiculata and H. celatrix), do not undergo a dormant period. They are native to areas with a more-or-less aseasonal climate (e.g. much of Peninsular Malaysia, Sarawak and Brunei). These differences, coupled with floral morphology characters, define what appears to be a natural division into two groups of allied species: H. appendiculata and H. celatrix and H. benthamiana, H. brownii H. ellipticifolia, H. colaniae and H. kerrii. Leaf blade variegation, in the form of irregular and diffuse silver grey to pale green blotches, has been reported in H. appendiculata, H. benthamiana, H. brownii and H. colaniae.

Inflorescence

All Hapaline species have white spathes occasionally tinged green or greyish pink. The spathe is always divided into two zones with the upper part flattened and erect to reflexed and the lower part clasping. The inflorescence is borne on a short to long, green to grey-pink mottled peduncle. At anthesis the peduncle is more-or-less erect to nodding. After fertilization it thickens and bends downwards, bringing the developing fruits to soil level. The spathe persists, the limb eventually breaking off or rotting away to leave the clasping lower spathe enclosing the ripening fruit (Fig. 2, G; Fig. 3 J). The spadix is bisexual with unisexual, naked flowers. The ovary consists of an ellipsoid, ovoid or bottle-shaped uniloculate, uniovulate ovary with a single anatropous ovule on the basal end of a parietal placenta. The positioning of the ovules results in an ovule that is functionally basal. The staminate flowers are 3-androus and fused into somewhat scattered to densely aggregated, peltate, synandria. The connectives are massively enlarged into a mushroom-like structure with the thecae inserted on the lower margin of the connective apex and dehiscing by an ovate pore (Fig. 3, G & H; Fig. 5, F & G). The male and female zones are separated by a few synandrodes. All species have a further zone of synandrodes situated at the spadix apex. In H. appendiculata, H. brownii Hook.f. and H. celatrix P.C. Boyce the spadix apex is enclosed by a cap formed of fused synandrodes; in the other species the synandrodes are free. A perfume has been reported from cultivated specimens of H. kerrii Gagnep. (Collins s.n. sub. Kerr 19462, K!) and faint but very pleasant perfumes are detectable from cultivated plants of H. benthamiana Schott, H. brownii, H. colaniae and H. celatrix (Boyce & Hay pers. obs.). No pollination studies have been undertaken.

Infructescence

Infructescences are known for five species (H. appendiculata, H. benthamiana, H. brownii, H. celatrix and H. colaniae). The berries are enclosed in the persistent lower spathe remains until maturity (Fig. 2, G; Fig. 3 J). When ripe the berries are globular to ellipsoid with slight to rather prominent stigmatic remains. The pericarp is leathery and the mesocarp sticky. Ripe berries are white and contain a single seed. The seeds are generally ellipsoid with a very thin smooth testa and a conspicuous raphe. The embryo is large, has a conspicuous plumule and lacks endosperm (Seubert 1993: 218 - 219). The ripe infructescence is held at soil level by the thickened and reflexed peduncle (see above). The method of seed dispersal is unknown.

Distribution

Hapaline species occur from Burma to southwestern China (Yunnan) and as far south as Brunei. Most species are quite rare, usually occurring as scattered colonies or occasionally individual plants. In Brunei, H. celatrix occurs as large isolated patches at the edge of lowland mixed dipterocarp forest. In Thailand, H. benthamiana occasionally occurs as extensive colonies formed as the result of its stoloniferous habit.