2. Pothos dzui

2. Pothos dzui P.C. Boyce, sp. nov.

Pothos dzui pedunculo longo, spatha pro ratione parva et stipite longo P. grandem arcte simulans, sed ab eo spadice crasso cylindrico inaeque in stipite prominenti longe decurrenti atque spatha valde reflexa facile separetur; P. cylindricum, speciem Philippinensem, praeterea spadice cylindrico simulans, sed ab ea lamina late elliptica atque petiolo brevi distinguitur. — Typus. Vietnam, Gia Lai, Mangyang, Chui Ta Moi, Nguyen Thi Nhan 532 (holo HN!),

Robust (homeophyllous?) root-climbing liane of unknown ultimate height. Eocaul, juvenile shoot and mature sterile shoot not observed; stem of fertile shoot to 5 mm diam., terete to somewhat angled in cross section. Leaves drying pale brown; petiole 10 – 55 x 2 – 10 mm, broadly winged, obovate-oblong oblong-triangular, with 2 – 3 secondary veins and numerous veinlets per side, all veins prominent, especially in dried material, base decurrent, apex truncate, rounded or very slightly auriculate; lamina 30 – 70 x 90 – 170 mm, elliptic to ovate with 2 – 4 intramarginal veins per side, these arising from the base and immediately diverging and then reaching the leaf tip, additional veins arising obliquely from the midrib, remaining parallel with numerous veins arising from them, base rounded to acute, apex attenuate-mucronate to acute or attenuate, minutely tubulate. Flowering shoot much abbreviated, arising from the proximal leaf axils of fertile shoots, bearing a minute prophyll and a few 3 – 10 mm sequentially longer cataphylls. Inflorescence solitary; peduncle 40 – 55 x 1.5 – 2 mm, rather stout, erect, twisting basally to present the inflorescences above the flowering shoot; spathe 17 – 20 x c. 20 mm, narrowly ovate, concave, prominently parallel-veined in dry material, margins strongly inrolled, base shallowly, cordate, clasping and decurrent on the peduncle, apex acute with a stout mucro; spadix stipitate; stipe c. 22 x 2 mm, terete in cross section, erect, straight; fertile portion 25 – 30 x 5 – 7 mm, stoutly cylindrical, bluntly rounded, unequally long-decurrent on the stipe. Flowers c. 1 mm diam.; tepals 1 x 0.3 mm, oblong-cymbiform, apex fornicate, triangular, truncate; stamens 1 – 2 x c. 0.25 mm, filaments strap-shaped, thecae c. 0.2 mm diam.; ovary 1 – 1.5 x 0.25 – 0.75 mm, compressed ellipsoid; stylar region truncate; stigma punctiform, margins slightly expanded.
Distribution — Vietnam.
Habitat & Ecology — Unknown.
Notes — Pothos dzui is a remarkable species known from a single collection of a solitary mature flowering branch with two mid-anthesis inflorescences. The inflorescence morphology (long peduncle, relatively small spathe and long stipe) is reminiscent of P. grandis from which P. dzui differs by the stout cylindrical spadix unequally long-decurrent on a prominent stipe and by the strongly reflexed spathe (vs. P. grandis in which the spadix is ovoid to clavate and the minutely cochleate at the insertion on a relatively short stipe and the spathe spreading to slightly reflexed). In the character of the cylindrical spadix P. dzui resembles P. cylindricus Presl (Philippines) from which it differs by the broad elliptic leaf lamina and short petiole.
It gives me considerable pleasure to name this species for Nguyen Van Dzu, my Vietnamese collaborator, expert on geophytic Indochinese aroids and excellent field companion, who first drew my attention to the collection in HN.

Collection studied:
VIETNAM. Gia Lai: Mangyang, Chui Ta Moi, Nguyen Thi Nhan 532 (fl.) (HN holo).