Arisaema silvestrii Pamp.

Tuber subglobose, ca. 2cm in diam. Cataphylls 3, greenish brown, membranous, apex obtuse. Leaves 2; petiole green, 24–35cm, basal 10–18cm sheathing and forming pseudostem, free part 13–30cm; leaf blade pedate; leaflets 7–9, sessile to sub-sessile, oblanceolate or oblong to elliptic, base cuneate, margin entire, apex acuminate; rachis between central and lateral leaflets 1–2.5cm, rachis between outer leaflets 5–10mm; central leaflet subsessile, 7–20 × 2.5–5cm; outermost leaflets 5–12 × 1.5–2.5cm. Peduncle shorter than petioles, 13–17cm, exserted from pseudostem 3–5cm. Spathe greenish white with 3–5 white stripes inside or (in female) dark purple with pinkish white stripes, ca. 15cm in total; tube funnelform, 5.5–6 × 2–2.5cm at throat; limb oblong or oblong-ovate, 7–8 × 3–3.5cm, acute at apex with an acumen 5–10mm. Spadix unisexual; male zone ca. 2 cm; synandria lax; anthers 2–4, thecae globose, dehiscing by apical pores; female zone ca. 2 × 1cm; ovary green; style short; stigma punctate. Appendix sessile, erect, greenish or purplish, cylindric, 4–7(–14)cm × 2–5mm, proximal part covered with a few acute neuter flowers.