Arisaema siangense Gusman, Syst. Geogr. Pl.

Arisaema siangense Gusman, Syst. Geogr. Pl. View in CoL 76: 229. 2006. Type: INDIA , Arunachal Pradesh, Siang District , c. 1300 m, July 1997, Gusman GG 97144 (holo BR849801 View Materials digital image!; iso CAL! & BM!). Fig. 25 View Figure 25

Deciduous, dioecious, perennial herb, to 1.85 m tall. Subterranean stem an annulate tuberous corm, subglobose or elongated, c. 6–12 cm diam., 5–14 cm tall, brown outside, offsets elongate and pyriform. Roots thick, pink to white. Cataphylls usually 3, 5–50 cm long, similar in colour to the pseudostem. Leaf solitary, radiatisect, emerging with the inflorescence; petiole 50–60 cm long, 1.5–2 cm thick, smooth, olive-green with carmine stripes; leaflets to 11, elliptic–obovate, 25–40 cm long, 7–9 cm wide, base cuneate or decurrent, subsessile or with a green petiolule, up to 10 mm long, apex long acuminate, margins undulate, green, entire or serrate, shiny green with deeply impressed veins above, underside glaucous with strongly prominent veins. Pseudostem 30–60 cm long, 3–4 cm wide, olive-green or pale red-brown with transverse vermillion markings and/ or carmine stripes. Inflorescence held below the foliage; peduncle shorter than the petiole, 5–20 cm long, c. 6– 1 cm thick, red-brown, with a mottling similar to the pseudostem. Spathe 18–33 cm long including tail; tube of spathe subcylindrical, 6–10 cm long, c. 1.5 cm wide above, narrowing in the upper third, c. 0.8 cm across, then flaring again at mouth, dark pink outside with faint paler stripes becoming olive-green near the spathe mouth, white-yellow inside with dotted purple stripes mainly in the lower half; mouth-margins straight to slightly recurved and olive-green; limb horizontal, ovate-lanceolate, 4–8 cm long (not counting the tip); 3–5 cm wide, shorter than the tube, outside and inside dull orange-yellow with pale pink stripes; acuminate at apex, prolonged into a tail, 8–15 cm long, olive-green turning pink at the end. Female spadix 6–10 cm long; pistils densely arranged; pistils many, bottle-shaped, sessile yellow-green; style short or absent; stigma white and penicillate; appendix subcylindrical, usually hardly exserted from the spathe tube, erect, 4–7 cm long, exceptionally extremely short, ending in a clavate, knobbly and light carmine apex, middle part white-yellow with pink stripes, smooth, 0.2–0.4 cm wide, lower part white-yellow, pink striped; neuters stiff, short and upcurved, 1–3 mm long, white-yellow, few in number; male fertile zone slightly conical, 1.5–3 cm long and 7–10 mm wide; male flowers loosely arranged, 2–4-androus; anthers pink, subsessile, dehisce through an elongated pore; pollens cream; neuters absent. Fruiting spike conical, 7–14 cm long and 3–6 cm wide, borne on an upright peduncle; receptacle cream-coloured; berries rounded, upper part flat, densely packed, bright red 1–3-seeded.

Flowering & fruiting: May–December.

Habitat: Grows at the base of deciduous trees, among bamboos and ferns, in clay, near streamlets and in bogs, at c. 1300 m elevation. A. siangense thrives along roads, often near riverbanks and among shrubs. Some specimens were over 1.80 m tall and this species might be the tallest in Sect. Sinarisaema .

Distribution: India (North-East Himalayas) , endemic.

Specimens examined: INDIA , Arunachal Pradesh, Upper Siang district, Yingkyong, 3 km east on Hills , 12.03.2004, Ritesh Kumar Choudhary 16242 ( ARUN!). Upper Dibang Valley district , Amboli, 08.05.1999, M . Bhaumik 2310 ( CAL!); Punli ,

30.04.1998, M . Bhaumik 1502 (CAL!).

Notes: This species is close to A. concinnum and one can easily misidentify this species when dried. However, it can be distinguished by its huge annulate corms, spathe tubes narrowed at middle, orange coloured spathe limbs and spadix appendix not knobbed as in the former.