Arisaema agasthyanum Sivad. & C.S.Kumar, Aroideana

Arisaema agasthyanum Sivad. & C.S.Kumar, Aroideana View in CoL 10(4): 19. 1987; Mohanan & Sivad., Fl. Agasthyamala 756. 2002; Gusman & L.Gusman, Gen. Arisaema , ed. 2. 357. 2006; Kottaim. & R.Ganesan, Ethnobot. Leaflets 12: 388. 2008. Type: INDIA , Kerala, Thiruvananthapuram district, Agasthyamala, 1869 m, 15.05.1985, Sathish Kumar TBG & RI-1350 (K). Fig. 1 View Figure 1

Deciduous, dioecious, succulent, perennial herbs, 50–65 cm tall. Subterranean stem a tuberous corm, subglobose, c. 3.5 cm diam., 2–3 cm tall, cream to light green. Roots many arising from the upper side of the corm, extensively long with secondary rootlets; tuberlets often present, surrounding the pseudostem. Cataphylls 3, rarely 4; outer c. 1.5 cm long, acute-obtuse at apex, often degenerated, decidedly mucronate, pale coloured; middle 5–7.5 cm long, rose to dull green towards the distal end; inner 12–18 cm long, dark coloured with faint greenish brown marks; often a degenerated outer cataphyll also present. Leaf solitary, radiatisect; petiole slender, c. 65 cm long, light green with faint dull green marks formed of vertical streaks; leaflets (3–5)–7–10, sessile, obovate-elliptic, 10.5–17 cm long, 3.5–5 cm wide, acuminate, margins slightly undulate, minutely praemorse, with a greenish dorsal border, dark green ventrally, pale-glaucous beneath, lateral veins up to 18 pairs, mid-vein flesh coloured mottled with minute rose-purplish spots. Inflorescence dioecious, not exceeding the height of the leaf; peduncle slender, 27–30 cm long, 0.6– 0.8 cm long thick, exserted by about 6–12 cm from the sheathing pseudostem, more or less completely enclosed in the petiole in male plants, light green with dull green marks formed of vertical streaks, often pale green without mottling. Spathe c. 25 cm long;tube of spathe cylindric, slightly funnel-shaped towards the mouth region, 5.5–6 cm long, 1.5–2 cm wide, striped with white and purple; margins of the mouth with auricular extensions; limb c. 19 cm long, c. 6 cm wide, galeiform, expanded in the middle, tapering to a purple caudate tail, white towards the base, dark purple distally. Female spadix sessile, 7–7.5 cm long, c. 0.5 cm wide, just reaching to the mouth of the tube; female fertile region 2–2.5 cm long; pistils many, compactly arranged, bottle-shaped, green; ovules 4–6; style short; stigma papillose, white to hyaline; neuters subulate, few, 1.5–2 cm long, scattered below the barren appendix up to 2 cm, upcurved, light green; appendix sub-cylindric, irregularly truncate and shortly stipitate, slightly swollen distally, warted on ageing, purple to green. Male spadix sessile, slender, naked or sometimes one or two neuters present; male fertile region 2–3 cm long; male flowers stipitate, scattered, 1–3-androus; anthers sessile, cream-white, forming an annular structure with rounded or circumscissile dehiscence, rarely anthers become free. Fruiting spike cylindrical, c. 5 cm long, c. 2.5 cm wide, borne on an upright peduncle; receptacle cream coloured; berries compactly arranged, green when young, orange-red at maturity, apex muticate, 3–6-seeded.

Flowering & fruiting: May–August.

Habitat: In grasslands, among bushes at an elevation above 1800 m, along with Adiantum sp. (Adiatntaceae), Canthium sp. , Hedyotis travancorica Bedd. , Psychotria sohmeri Kiehn. ( Rubiaceae ), Memecylon sp. ( Memecylaceae ) and Liparis sp. ( Orchidaceae ).

Distribution: India (southern Western Ghats), endemic.

Specimens examined: INDIA , Kerala, Thiruvananthapuram district, Agasthyamala , 22.05.1901, C . A . Barber 2910 ( CAL!); ibid., Athirumala , c. 1200 m, 24.06.1993, N . Mohanan 11452, 11453 ( TBGT!); Pongalappara , 1400–1600 m, 15.05.1988, N . Mohanan 9807, 9808 ( TBGT!); ibid., c. 1560 m, 11.06.2011, Manudev 4451 ( CALI!); ibid., 05.06.2014, Manudev & Arunkumar 138922 ( CALI!); ibid., 07.06.2015, Arunkumar & Manudev 144919 ( CALI!); ibid., 06.07.2015, in fruiting, Arunkumar & Rajeevan 144916 ( CALI!); ibid., 06.07.2015, in flowering, Arunkumar & Rajeevan 144918, 144919 ( CALI!); ibid., 01.08.2015, in fruiting, A . J. Robi s.n .

Notes: Similar to A. translucens C.E.C.Fisch. , but can be distinguished by its galieform, expanded limb and annulate staminate flowers. Other than this species, annulate staminate flowers are seen

only in A. exappendiculatum H.Hara , a species endemic to Nepal.

Conservation status: The population size at the type locality, Pongalappara is very low, consisting of hardly 20 plants. Based on ‘ Extent of Occurrence’ ( EOO <100 km 2; Criterion B1 ), ‘ Area of Occupancy’ [Criterion B2 : AOO<10 km 2 with Extreme fluctuations in number of subpopulations [sub-criterion ‘c (iii)’], and number of mature individuals (Criterion D), A. agasthyanum has been assessed here as ‘CRITICALLY ENDANGERED’ [ CR: B1 , B2 b(iii & iv), B2 c(iii) & D] according to IUCN’s guidelines ( IUCN SPS, 2017).