勐腊南星 meng la nan xing

Plants perennial, evergreen, monoecious or male. Rhizome erect, light brown outside, violaceous in section, oblique or horizontal, cylindric, 5-6 × 2.5-3 cm, with numerous nodes bearing buds, roots 10-15 cm. Pseudostem absent. Cataphylls 5, flesh-colored, 5-8 × 1.5-2 cm, membranous, 2 encircling petiole and peduncle, 3 enclosing peduncle directly. Leaves 1 or 2, arising at different seasons from different rhizome nodes; petiole viridescent with inconspicuous white spots, cylindric, ca. 45 cm × 5-8 mm; leaf blade green, 3-foliolate; central leaflet with petiolule ca. 1.7 cm, blade elliptic, ca. 21 × 11 cm, base cuneate, apex acuminate with acumen ca. 1 cm; lateral leaflets with petiolule ca. 1.5 cm, blade obliquely broadly lanceolate, ca. 20 × 8 cm, base broadly cuneate, apex acuminate with acumen 0.9-1 cm; lateral veins 7-9 on each side, collective vein 4-9 mm from margin. Peduncle green, cylindric, shorter than petioles, ca. 20 × 0.5 cm. Spathe green, with numerous longitudinal veins; tube funnel-shaped, ca. 7 × 1.5-3 cm, throat margin recurved to 8 mm wide; limb bent forward, oblong, ca. 6.5 × 4 cm. Bisexual spadix ca. 3.5 cm; female zone ca. 1.5 cm; female flowers densely arranged; ovary greenish, obovoid, ca. 2.5 × 1-2 mm; ovules 4, erect; male zone ca. 2 cm; synandria sparse; synandria of 2 or 3 fused stamens; stalk ca. 2 mm; anthers 3, each comprising 2 thecae; thecae subglobose, ca. 1 mm in diam., dehiscing by an apical slit; appendix sessile, erect, proximally purple, distally green, ca. 5.5 cm × 1-4 mm, usually exserted from spathe tube by ca. 1 cm, wholly covered by filiform neuter flowers; neuter flowers erect, green, 5-10 mm. Male spadix ca. 3 cm × 2 mm; appendix ca. 5 cm. Fl. Dec-Feb.

● Tropical seasonal forests; 1000-1100 m. S Yunnan (Mengla).

This taxon is very close to Arisaema omkoiense Gusman (Syst. Geogr. Pl. 71: 3. 2001), from N Thailand, and A. pingbianense.