Anadendrum chlorospathum V.D.Nguyen, Q.D.Dinh & P.C.Boyce, 2019

Anadendrum chlorospathum V.D.Nguyen, Q.D.Dinh & P.C.Boyce View in CoL , sp. nov. — Fig. 1 View Fig , 2 View Fig

Anadendrum chlorospathum is unique in the genus by a glossy medium green spathe, flowers in which the perigone is much shorter than the gynoecium, and anthers longer than the filaments at anthesis. — Type: Dinh QD & Le TH KB032 (holo HN; iso K), Vietnam, Gia Lai province, K’Bang district , So Pai village , E108°34'39" N14°19'34", 781 m elevation, 26 Apr. 2017 GoogleMaps .

Etymology. The species name reflects the uniquely green spathe.

Evergreen, medium sized nomadic vines to 2 m. Juvenile shoots stoloniferous on ground; stem 5–6 mm diam, with conspicuous nodes giving a segmented appearance, internodes 5 –10 cm long, active portions green, ageing brown, rooting to 15–20 cm long at internodes. Adult shoots climbing; stem cylindrical, 4 –6 mm diam, segmented in appearance by the presence of abrupt nodes, internodes 2–2.5 cm long, drying black; clinging roots 3–4 cm long, feeding roots 20–100 cm long, reaching to ground. Leaves distichous, scattered on juvenile and climbing sterile shoots, forming a dense fan in flowering shoots; petiole geniculate, 6–8 cm long, sheath extending to the geniculum, 3–7 by 1–4 mm wide, membranous, marcescent, degrading into long pieces, grey-green; leaf blade weakly oblique, elliptic to lanceolate, oblong, 5.5–16 by 2.7–5.5 cm wide, base obtuse to round, apex acuminate, apiculate 2–2.5 cm long, tip with spike 1–2 mm; dark green above, paler and slightly glaucous beneath when fresh, drying grey brown (air-dried) to black grey (alcohol preparation prior to drying); lateral veins 4–7 per side, prominent, 1–2.5 cm distant; interprimary veins well distinguished from minor veins, 1–1.2 mm distant; highest order veins reticulate; first inflorescence of a flowering event preceded by a much smaller leaf with petiole sheath 7–10 cm long, 1.3–1.8 cm wide, enclosing peduncle, upper portion free of petiole, very narrow and short, forming a much-reduced blade, 1–1.3 cm long by 1–1.2 mm wide. Inflorescence 1–3 in each floral shoot; peduncle spreading and carried at almost 90° to the shoot with spadix erect by a sharp bend at the junction of spathe to peduncle, peduncle cylindrical, 7–18 cm long, c. 1–2.5 mm diam, enclosed by preceding leaf sheath to over 1/2 length (first inflorescence in sympodium) by cataphylls (subsequent inflorescences); spathe elliptic to oblong ovate, c. 9.5 cm long by 2.5 cm wide, apex long-acuminate, cadu- cous, glossy medium green internally, somewhat less glossy externally; spadix stipitate, stipe rather stout, 1.2–1.7 cm long by 2–2.5 mm diam; fertile portion cylindrical to slightly conical, size 6–7.5 by 0.6–1 cm, flowers congested, at anthesis initially white, later becoming green and eventually orange-red postanthesis; flowers bisexual; perigone very short, inconspicuous, 0.6–0.7 mm tall, forming a ring at base of gynoecium; stamens 2.5–3 mm long, filaments broadly conical, 1.5–2 mm long, anther 3 mm long; gynoecium obpyramidal, tetragonal, white when young, c. 5 by 3 mm; ovary 1 locule, 1 ovule; stylopodium rhomboidal, truncate, top c. 3 by 3 mm; stigma transverse-linear, 2/3 length of surface. Fruits berries, obovate, apex truncate, hexagonal, 6–7 mm diam, initially dark green ripening through yellow to scarlet.

Distribution — To date known only from K’Bang district, Gia Lai province.

Habitat & Ecology — Secondary evergreen broad leaf forest and evergreen moist shady forest between 300–781 m elevation, dominated by Lithocarpus sp. and Dysoxylum sp.

Phenology — Anadendrum chlorospathum flowers in the late March to the end of April, fruits matured in the end of April to May.

Conservation status — Anadendrum chlorospathum is commonly found in K’Bang district, Gia Lai province, Central Vietnam. Possible threat would be the reduction of forest area of the Tay Nguyen plateau owing to expansion of agriculture land. Based on the IUCN (2018) threat assessment criteria, A. chlorospathum should be assigned the NT status (Near Threatened) A2ac+3bc+4abc.

Other specimens examined. VIETNAM, Gia Lai Province, K’Bang district, Song lang, 24 Apr. 1978, N. H . Hien 424 ( HN); K’Bang district , 25 Apr. 1978, L. K . Bien 806 ( HN); K’Bang district , 5 Dec. 1978, L. K . Bien 997 ( HN); K’Nak, 24 June 1998, N. V . Du & P. C Boyce 1315 ( HN, K) .

Notes — This paper is to be considered very much a first attempt at understanding the taxonomy of Anadendrum for Indo-China. As with the precursory account for the Flora of Thailand ( Boyce 2009) wherein comments on interpretation of historical material that are equally pertinent here, a pragmatic approach is being used to at least attach names to the most distinct taxa until such time as someone is able to undertake a much needed field-based revision for the genus throughout its entire range.