5. Pothos kerrii Buchet ex P.C. Boyce, sp. nov.

[P. kerrii Buchet apud Gagnep. in Lecomte, Fl. Gén. l’Indo-Chine 6 (1942) 1085, nom. invalid., sine descr. Latin.; P.H. HÈ, Cây-cÀ Miê__ Nam Vi_t-nam [Fl. South Vietnam – in Vietnamese] (1960) 690, pl.267, G (Pothos scandens sic.); H. Li in C.Y. Wu & H. Li, Fl. Reip. Pop. Sinicae 13(2) (1979) 19, pl.3, 8; J. Zhong, Ill. Limestone Mount. Pl. Guangxi (1982) 291; P.H. HÈ, CâaycÀ Vi_tnam [Ill. Fl. Vietnam – in Vietnamese & English], 3(1) (1993) 421, pl.8256] [P. guangxiensis H. Li, nom. nud. in sched. KUN]

Pothos kerrii pedunculo stipiteque longo pergracili, spadice fertili globoso parvulo egregius est in genere; P. pilulifero nuper descripto leviter similis, sed pedunculo aliquantum longiore (fere in P. pilulifero absenti), stipiteque longiore pergraciliore distinguiter — Typus: Lao P.D.R., Tau-yeng (Tawieng), 5 April 1932, Kerr 20900 (fl.) (P! holo; BK!, K! iso).

Medium-sized slender homeophyllous root-climbing liane to 4 m. Eocaul not observed; stem of juvenile shoot to 2 mm diam., weakly angled or terete in cross section, leaves congested; stem of mature sterile shoot to 6 mm diam., terete in cross section, at first somewhat densely clothed with leaves, stems eventually becoming naked, naked portions with prominent nodes to 50 mm distant, stem mid-green; fertile shoot often branching to three or more orders, stem to 3 mm diam., terete in cross section, mostly densely clothed with leaves, older portions naked at the base, naked portions with nodes to 30 mm distant; foraging shoot to 2 mm diam., proximally with a few oblong cataphylls and reduced foliage-leaves at first but soon becoming naked with slightly prominent nodes to 100 mm distant. Leaves when fresh mid-green, air drying dull green to brownish; petiole 10 – 30 (– 50) x 5 – 10 mm, broadly winged, oblong to oblong-triangular, , with 2 – 4 secondary veins per side, veins prominent, especially in dried material, base decurrent to clawed, apex truncate to auriculate; lamina 75 – 130 x 12.5 – 25 mm, lanceolate to slender-elliptic, with 2 – 3 intramarginal veins per side, these arising from the base and immediately diverging and reaching the leaf tip, base rounded, apex long-attenuate-mucronate to acute, minutely tubulate. Flowering shoot much abbreviated, arising from the middle to distal leaf axils of fertile shoots, bearing a minute prophyll and a few 3 – 10 mm, sequentially longer cataphylls. Inflorescence solitary; peduncle 25 – 40 x 0.5 – 1 mm, deep purple, very long and slender, erect to spreading, curving to bring inflorescence upright,; spathe ovate, 4 – 6 x 3.5 – 7 mm, deeply concave to almost flat, margins straight, base prominently cordate, clasping and minutely decurrent on the peduncle, apex obtuse with a small but prominent mucro, greenish purple; spadix stipitate; stipe 10 – 18 x 0.23 – 0.75 mm, terete in cross section, erect, straight, deep purple; fertile portion 3.5 – 4 x 3.5 – 4.5 mm, globose, pale yellow. Flowers c. 1 – 2 mm diam.; tepals 1 x 0.3 mm, oblong-cymbiform, pale yellow, apex fornicate, triangular, truncate; stamens 1 – 3 x c. 0.35 mm, filaments strap-shaped, thecae c. 0.2 mm diam., yellow; ovary 1 – 1.5 x 0.25 – 0.75 mm, compressed angular-ellipsoid, yellow-green to dirty white; stylar region truncate; stigma punctiform. Infructescence with 1 – 7 berries; fruit 10 – 15 x 7.5 – 10 mm, obclavate to ellipsoid. Seeds c. 3 – 6 mm diam., ellipsoid to compressed-globose.

Distribution — China (Guangxi), Lao P.D.R., Vietnam.

Habitat & Ecology — Seasonal rather dry evergreen hill forest forest on precipitous granite slopes. 400 – 550 m.

NotesPothos kerrii is distinctive by the short petioles and long, narrow leaf lamina with prominently raised veins and by the graceful inflorescences with a very long, almost filamentous peduncle, a long slender stipe and small spherical fertile spadix. Confusion can occur with P. kerrii in Vietnam and China where P. pilulifer is superficially similar. Pothos pilulifer differs in having broader leaves and an inflorescence with a very short, stout pedicel, a stout, straight stipe and a larger fertile spadix.
Rather few collections of P. kerrii exist, although this may be an artefact of collecting rather than a reflection of natural rarity considering the widespread provenance of the known collections. During fieldwork in 1997 at Bach Ma, Quang Nam – Da Nang province, Vietnam, P. kerrii was a ubiquitous element of the forest liane flora (Boyce & Dzu, pers. obs.) but seldom flowering.

Geographically representative selection of collections studied:
CHINA. Guangxi: Ninming County, 11 Oct. 1979, Longgan Exped. 11605 (fl.) (KUN).
LAO P.D.R. Louangphrabang: Louangphrabang, 019° 52’N, 102° 08’E, April 1913, d’Alleizeite s.n. (fl.) (L). Xieng Khouang: Tau-yeng (Tawieng), 5 April 1932, Kerr 20900 (fl.) (type of Pothos kerrii, P holo; BK, K iso).
VIETNAM. Hoa Binh: Muong Khen, 020° 40’N, 105° 20’E, April 1933, Petelot 4691 (fl.) (P). Lang Son: Hui Lui, 2 Oct. 1996, Nguyen Van Dzu 104 (fl.) (HN). Quang Nam – Da Nang: Go Oi, 22 Feb. 1941, Poilane 31452 (fl.) (AAU, K, L, P). Yen Bai. Dong Tam, 021° 30’N, 105° 00’E, 5 May 1961, Soviet-Vietnam Expedition 1806 (fl, fr.) (LE).