Aridarum Ridl.

Small to medium-sized, evergreen herbs. Stem decumbent, erect distal part sometimes rather long. Leaves several, spiral or rarely distichous (A. borneense); petiole sheathing only at base, with long, marcescent ligule; blade coriaceous, linear to elliptic, apex with tubular mucro; primary lateral veins pinnate, weakly or not differentiated, running into distinct marginal vein, higher order venation parallel-pinnate. Inflorescence solitary, sometimes more or less nodding; peduncle subequal to or longer than petiole, sometimes more or less deflexed at apex. Spathe stoutly ellipsoid, not constricted, convolute and gaping at apex only or broadly boat-shaped and widely gaping to base, lower part persistent, green, upper part caducous, white, cuspidate to acuminate at apex. Spadix sessile, cylindric, normally with a few sterile flowers at extreme base, female zone cylindric; pistil naked, shallow, laterally compressed, subhexagonal to subglobose; ovary 1-locular, ovules many, orthotropous to hemiorthotropous, funicle distinct, erect, placenta basal, stigma sessile, slightly concave centrally, as broad as ovary, usually more or less contiguous with neighbouring stigmas; sterile interstice short to absent, composed of sterile stamens; male zone subcylindric to ellipsoid; male flower 2-androus or not recognisable (unistaminate); filaments distinct to very short, free to connate, connective slightly to deeply excavated (rarely not excavated - A. incavatum), thecae either opposite or paired on one side of the anther and then situated inside or outside connective cavity, apically narrowed into long or short horn or needle, dehiscing by single apical pores; pollen inaperturate, ellipsoid-oblong, small (mean 23 mm, range 16-31 mm (Grayum, 1992: 21)), exine psilate. Infructescence a cluster of berries subtended by the obconic persistent lower spathe; berries globose or ellipsoid to cylindric, stigma remnant persistent; seeds ellipsoid, elongate, with long curved transparent interlinked micropylar appendages; testa longitudinally costate, embryo elongate, endosperm copious.