Arisaema petiolulatum Hook.f.

Plants monoecious and male, evergreen. Rhizome pale yellow outside, purple or violet in section, cylindric. Cataphylls withering, yellowish red to creamy red, narrowly lanceolate, membranous. Leaf 1; petiole encircled by cataphylls, pale, unspotted, to 40cm, base sheathing for ca. 1.5cm; leaf blade pale green abaxially, green adaxially, papery, 3-foliolate; central leaflet with petiolule ca. 2cm, blade elliptic, 9–25 × 5.8–10cm, base obtuse or shortly cuneate, apex acuminate; lateral leaflets with petiolule 5–10mm, blade elliptic-lanceolate, 8–20 × 3.5– 9.5cm, base obliquely rounded. Peduncle encircled by 2 cataphylls, separated from petiole, terete, 25–35 × 1.2–1.5cm. Spathe tube greenish white, with ca. 1cm white base, ca. 5cm × 8mm, throat margin narrowly auriculate, outwardly recurved, auricle ca. 8mm wide; limb arching, green with a large rounded white area at base, ovate-lanceolate, ca. 6 × 3cm, membranous, with a tail ca. 5mm. Spadix bisexual in mature plants, unisexual (male) in small plants. Bisexual spadix: basal female zone cylindric, ca. 1.5cm, ca. 5mm in diam. at base, densely flowered; ovary oblong; ovules 2–4, basal, erect; style short but distinct; stigma capitate, pilosulose; continual male zone ca. 1.5cm with sparse male flowers; synandria of 2 or 3 stamens; anthers sessile, or filaments ca. 1 mm; thecae subglobose, opening by an apical slit; appendix erect, sessile, green, narrowly cylindric, without neuter flowers, distally slightly rugose. Unisexual spadix: male zone ca. 2cm, ca. 3.5mm in diam. with a stipe ca. 2mm; appendix as in bisexual spadix, with or without 2 or 3 subulate neuter flowers in proximal part.