Aridarum Ridl.

CATE Araceae, 17 Dec 2011. araceae.e-monocot.org

Diagnostic

Rheophytes; petiole sheath with long marcescent ligule; blade apex with tubular mucro; spathe persistent in lower half, upper part caducous; thecae horned. Differs from Bucephalandra and Phymatarum in spathe stout, not constricted, spadix with short apical zone of sterile flowers but lacking a conspicuous appendix, stigma as broad as ovary.

Habitat

Tropical humid forest; rheophytes.

General Description

HABIT : small to medium-sized, evergreen herbs, stem decumbent, erect distal part sometimes rather long. LEAVES : several, spiral or rarely distichous ( A. annae). PETIOLE : sheath 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 ± nodding. PEDUNCLE : subequal or longer than petiole, sometimes ± 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 : cylindric, normally with a few sterile flowers at extreme base, female zone cylindric, shorter than male and separated from it by equally thick zone of sterile male flowers, male zone equally thick, with shorter apical zone of sterile flowers, apex obtuse. FLOWERS : unisexual, perigone absent. MALE FLOWER : 1-2-androus, filaments distinct to very short, free to connate, connective slightly to deeply excavated, thecae either opposite or paired on one side and situated inside or outside connective cavity, apically narrowed into long or short horn, dehiscing by apical pore. POLLEN : inaperturate, ellipsoid-oblong, small (mean 23 µm., range 16-31 µm.), exine psilate. STERILE MALE FLOWERS : consisting of prismatic to obpyramidal, truncate staminodes with or without a small, central, apical cavity. FEMALE FLOWER : gynoecium 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, contiguous with neighbouring stigmas. BERRY : globose or ellipsoid to cylindric, stigma remnant persistent, infructescence globular to slightly elongate. SEED : ellipsoid, elongate, testa longitudinally costate, embryo elongate, endosperm present.

Distribution

NW. Borneo.