Apoballis
Small to moderate herbs. Stem pleionanthic, epigeal, erect to decumbent. Leaves few to many, often clustering terminally on the shoot, innovations generally pink; petiole usually glabrous, sometimes minutely puberulent, leaf sheath fully attached, tapering, persistent to slowly degrading in the marginal distal part; leaf blade oblanceolate to ovate-sagittate, sometimes variegated, glabrous adaxially and abaxially, basally cuneate to sagittate, apex acute to long acuminate; primary and secondary venation bipinnate, tertiary venation obscure. Inflorescence solitary or to 5 in a synflorescence; spathe long, to 20 cm; lower spathe, ovoid, differentiated from the spathe limb with a gradual or abrupt constriction; spathe limb oblong-lanceolate, upper spathe persistent until well after anthesis, then deliquescing, opening only slightly, the distal portion remaining convolute, with only the ventral part of the staminate flower zone exposed; spadix equalling or shorter than spathe; pistillate flower zone more or less cylindrical, obliquely inserted to adnate for up to ½ of its length; pistils globose, sessile; interpistillar staminodes present or absent; interstice prominent, mostly naked with a few groups of small, more or less sessile staminodes; staminate flower zone cylindrical to slightly tapering, the lower part corresponding with the spathe constriction; stamens crowded, dumbbell-shaped to irregular; appendix present; fruiting spathe urceolate, declinate. Fruits and seeds not seen.
Apoballis is defined by the deciduous leaf sheath, pistillate and staminate flower zones separated by a prominent naked interstice interspersed sparsely with staminodes, and a spathe that hardly opens, and is semipersistent into fruiting. Further, all species so far investigated have spiny pollen (smooth in Schismatoglottis and all other Schismatoglottideae). Apoballis produces a floral odour reminiscent of benzaldehyde (almond oil), contrasting to Schismatoglottis (methyl esterase). This, together with the differences in spadix arrangement and spathe mechanics, suggests pollinator differences.
About 13 species from S. Myanmar to S. Thailand, Sumatra (the majority), and Peninsular Malaysia. Two species in Thailand.