23. Remusatia Schott in Schott & Endlicher, Melet. Bot. 18. 1832.
岩芋属 yan yu shu
Authors: Heng Li & Peter C. Boyce
Gonatanthus Klotzsch.
Herbs, small to medium sized, seasonally dormant, epiphytic or epilithic, rarely terrestrial, latex-bearing. Tuber subglobose, producing erect to spreading, unbranched or branching stolons from axils of scarious, deciduous cataphylls; stolons producing small, ovoid tubercles at nodes, each invested by numerous apically hooked scales (minute cataphylls). Leaves 1 or 2; petiole sometimes slender, sheath relatively short; leaf blade peltate, cordate-lanceolate to cordate-ovate, apex acuminate; basal veins well developed, primary lateral veins pinnate, forming submarginal collective vein very close to margin, marginal vein also present, secondary and tertiary laterals arising from primaries at a wide angle, then arching toward leaf margin and forming inconspicuous interprimary collective veins, higher order venation reticulate. Inflorescences solitary or up to 3 together, appearing with or without leaf; peduncle shorter than petioles. Spathe strongly constricted between tube and blade, sometimes with secondary constriction above spadix (this group formally recognized as a separate genus: Gonatanthus); tube with convolute margins, persistent, enclosing female zone and sterile zone of spadix; limb yellow or red, longer than tube, fully expanded or remaining convolute and opening only at base, sometimes becoming reflexed (in Remusatia vivipara and R. yunnanensis), later deciduous. Spadix sessile or subsessile, much shorter than spathe; female zone subcylindric, ca. 1/2 as long as spathe tube, separated from male zone by much narrower zone of sterile male flowers; male zone ellipsoid or subclavate, fertile to apex, obtuse. Flowers unisexual, naked. Male flowers 2- or 3-androus; stamens connate into cuneate-clavate, 4-6-sulcate synandrium; fused filaments distinct; common connectives somewhat excavated at apex; thecae 4-6, oblong to ellipsoid, dehiscing by apical porelike slit; synandrodes each ± elongated. Pistils lacking associated staminodes; ovary subcylindric to subglobose, 1-loculed or partially 2-4-loculed at apex; ovules many, hemiorthotropous; funicle short to long; placentae 2-4 and parietal or placenta 1 and basal; stylar region very shortly attenuate or appearing lacking; stigma disciform-subcapitate or slightly 3- or 4-lobed. Fruit an obovoid to globose, many-seeded berry; infructescence ellipsoid, borne within persistent spathe tube. Seed ellipsoid to subglobose, covered by thick, fleshy sarcotesta or testa verruculose to irregularly costate; embryo axile, ovoid to subglobose, short; endosperm copious. 2n = 28, 42.
Four species: S and SE Asia, one (Remusatia vivipara) extending from Africa and Madagascar to tropical Asia, Australia, and the Pacific islands; four species (one endemic) in China.
