14. Pothos touranensis Gagnep.

Pothos touraensis Gagnep., Notul. Syst. 9 (1941) 136; Gagnep. in Lecomte, Fl. Gén.l’Indo-Chine, 6 (1942) 1082 – 1090; P.H. HÈ, CâaycÀ Vi_tnam [Ill. Fl. Vietnam – in Vietnamese & English], 3(1) (1993) 420 – 423, pl.8262. — Type: Vietnam, Lien-chieu, near Tourane (modern Danang), 19 Aug.1923, Poilane 7643 (fl.) (P! holo).

Moderately robust heterophyllous (?) root-climbing liane to 7 m. Eocaul not observed; stem of juvenile shoot to 2 mm diam, flexuous, terete in cross section, producing adherent flattened feeding roots; stem of fertile shoot to 5 mm diam., terete in cross section, mid-green to brown in dried material, leaves scattered, spreading. Leaves brownish green to yellow-brown in dried material; petiole 80 – 150 x 4 – 11 mm, canaliculate, rounded abaxially, narrowing towards geniculum, base decurrent, apex prominently geniculate, geniculum at first smooth, later corky, sheath very prominent, apically pronounced-ligulate, especially in young growth, sheath extending to geniculum; lamina 130 – 200 x 50 – 85 mm, broadly to narrowly oblong elliptic, 2 intramarginal veins per side, 1 – 15 mm from lamina margin, arising from just above base of the midrib, remaining ± parallel to margin, terminating at the tip of the lamina, base obtuse to broadly rounded, apex acuminate to long-acuminate, apiculate. Flowering shoot (always?) contiguous with fertile shoot, inflorescence (always?) terminal on a leafy fertile/flowering shoot. Inflorescence solitary; peduncle 100 – 190 x c. 2 mm, robust, curving or straight, occasionally strongly bent basally, the inflorescence held erect, drying dark brown; spathe 60 – 90 x 15 – 20 mm, triangular, base rounded to truncate, decurrent on peduncle, apex acuminate; spadix stipitate; stipe 10 – 15 x 1 – 2 mm, stout, terete; fertile portion 35 – 55 x 3 – 4 mm, tapering-cylindric. Flowers 1.5 – 3.1 mm. diam; tepals, broadly ovate to fornicate, 1.5 x c. 1 mm; stamens 0.75 x c. 0.5 mm, filaments strap-shaped, thecae 0.25 x 0.25 mm, oblong ellipsoid; ovary 0.5 x 1.25 mm, compressed-globose to hexagonal-turbinate; stylar region large, truncate; stigma small, punctiform. Infructescence with few fruits; berries (immature) c. 2 x 3.5 mm, obturbinate.

Distribution — Vietnam.

Habitat & Ecology — Rather dry mixed hill forest on granite, on trees in very rocky soil. 700 – 750m.

Notes — An extraordinary species, immediately recognizable in Indochina by the immensely long peduncle a character otherwise unknown in the review area but present in, e.g. P. mirabilis Merr. (Borneo) and P. tener Wall. (Borneo, Sumatera). Very few collections of P. touranensis have been made and, as with P. gigantipes, this seems to reflect natural rarity rather then undercollecting.

Geographically representative selection of collections studied:
VIETNAM. Khanh Hoa: Nha Trang, Co Inh massif, 17 Sept. 1922, Poilane 4593 (fl.) (P). Quang Nam – Da Nang: Lien Chien, 19 Aug.1923, Poilane 7643 (fl.) (type of Pothos touranensis, P holo).