Amomum kingii var. oblongum V.P. Thomas & M. Sabu, 2015

Thomas, V. P., Nissar, Muhammed & Sabu, M., 2015, Amomum kingii var. oblongum (Zingiberaceae): a new variety from Sikkim Himalaya, Phytotaxa 220 (1), pp. 89-94 : 89-91

Amomum kingii var. oblongum V.P. Thomas & M. Sabu , var. nov. ( Fig. 2 & 3 )

Similar to Amomum kingii Baker (1892:241) but differs from it in having oblong spikes (25–50 cm long), laxly arranged flowers, green coloured pseudostem sheath with pale pink margins, oblong to oblanceolate (9–13 cm long) sheathing bracts, lanceolate bracteoles and oblong (3.8–4.5 cm long) fruits. Other minor differences are given in Table 1.

Type:— INDIA. Sikkim: East Sikkim District, Pangthang, alt. 1890 m, 7 May 2007, V. P. Thomas & V. A. Muhammed Nissar 95501 (holotype CALI!, isotype CAL!).

Rhizome non-stoloniferous, stout, robust, 4–5 cm thick, pale yellow inside, covered with scales; scales coriaceous, glabrous. Leafy shoots 300–350 cm tall, robust, clump forming; sheath ca. 4 cm wide at base, green with pale pink margins, lined with prominent parallel veins, margin membranous, glabrous. Leaves 8–10 per shoot; lamina oblong-lanceolate, 27–120 × 10–25 cm, dark green above, glaucous beneath, base oblique, apex acuminate, glabrous on both surfaces except a layer of hairs near margin beneath; midrib pink, glabrous; veins appressed above; petiole 2.5–4 cm long, green, glabrous. Ligule entire, 1–2 cm long, green tinged with pink, apex acute to rounded, margin ciliate, pubescent inside groove. Inflorescence 25–50 cm long, many flowered, arise from rhizome just below the aerial shoot; peduncle 8–15 cm long. Sheathing bract 6–9 per inflorescence, oblong or oblong-lanceolate, 9–13 × 3.5–5 cm, brown, margin ciliate, connate margins with adjacent bracts, glabrous and rarely puberulous externally. Bract 2.6–3 × 0.5–0.7 cm, membranous, early drying, white, margin ciliate, apex acute to rounded, glabrous. Bracteole non-tubular, represented by rudimentary lanceolate structure, 0.8–1.2 × 0.1–0.2 cm, membranous, white tinged with pink, non-tubular, margin ciliate, glabrous. Flower 5.5–6 cm long, white tinged with yellow, borne singly from each bract; pedicel pubescent. Calyx 3-lobed, ca. 2.5 × 0.8 cm, membranous, white, a small notch present at tip of each lobe, cleft 0.5–1.2 cm deep, puberulous towards apex externally, glabrous within. Corolla tube ca. 2 cm long, ca. 0.3 cm wide at mouth, white, pubescent externally, pubescent within, densely towards mouth; dorsal corolla lobe oblong, 2.4–2.6 × 1.2–1.4 cm, white, margin rarely distantly ciliate towards base, apex hooded, pubescent externally, glabrous within; lateral corolla lobes oblong, 2.2–2.3 × ca. 0.9 cm, pubescent externally, glabrous within. Labellum obovate, 3-lobed, ca. 3.5 × 2.5 cm, white towards periphery, centre with spreading pink bands from base, red tinged at base, margin crenulate, crumbled, pubescent internally towards lower part. Lateral staminodes ribbon-like, flat, 1.2–1.5 cm long, tapering towards apex, white, lower part red, densely pubescent towards base, glabrous towards apex. Stamen 2.3–2.5 cm long, filament ca. 0.8 × 0.4 cm, white, pink towards base, pubescent on both surfaces; connective pubescent; crest irregularly lobed, 0.6–0.7 × 0.8–0.9 cm, white, glabrous, puberulous externally; anther thecae oblong, 1.2–1.3 cm long, cream-coloured, base tapering, apex diverging, glabrous; dehiscing throughout their length. Epigynous glands irregularly split, 0.3–0.4 cm long, cream coloured, apex truncate, glabrous. Ovary oblong, 0.8–1.1 × 0.5–0.6 cm, glabrous; locules 3; ovules many on axile placentae; style ca. 4.4 cm long, puberulous towards tip; stigma cup-shaped, ca. 0.1 cm across, white, mouth ciliate, opening terminal. Infructescence 30–60 cm long, many in a spike; peduncle ca. 15 cm long; calyx persistent. Capsule oblong or ovate-oblong, smooth walled, no apical depression, 3.8–4.5 × 2.2–2.5 cm, pale pink to white, glabrous, stalk 0.5–0.7 cm long. Seeds many, angular, 0.3–0.6 × 0.3–0.4 cm, brown, aromatic, glabrous, arillate; aril white.

Flowering & Fruiting:—March–August.

Distribution:—Known only from the type locality Pangthang, East Sikkim District of Sikkim.

Proposed IUCN status:—The IUCN status ( IUCN 2001; IUCN 2012) has been analyzed for the taxa and determined as Critically Endangered (CR B2ab(i,ii);D). The area of occupancy is estimated to be less than 10km 2 and known to exist only in a single location. A continuous decline in quality of habitat and extent of occurrence is noticed. The population size is estimated to number fewer than 50 mature individuals. Expansion of large cardamom plantations and other anthropogenic activities amplify pressure on the fragile habitat and existing individuals.

Ecology:—In shaded places at high elevations of Sikkim Himalaya.

Etymology:—The specific epithet ‘oblongum’ refers to the oblong shape of the inflorescence and the fruits.

Figures

FIGURE 2. Amomum kingii var. oblongum var. nov.A. habit; B. ligule; C. inflorescence; D. outer bract; E. inner bract; F. bracteole; G & H flowers; I. calyx with ovary; J. corolla lobes; K. labellum with lateral staminodes; L. stamen; M. ovary with epigynous glands and part of style; N. stigma; O. infructescence. Photos by V.P. Thomas.

FIGURE 3. Amomum kingii var. oblongum var. nov. A. part of leafy shoot; B. ligule; C. inflorescence; D. bract; E. bracteole; F. flower; G. calyx; H. corolla lobes; I. stamen; J. labellum; K. ovary with epigynous glands and style; L. stigma; M. c.s. of ovary, N. fruit; O. seed. Drawn by V.P. Thomas.