Piper mestonii F.M.Bailey

Gardner, R. O., 2013, Piper (Piperaceae) in New Guinea: the climbing species, Blumea 57 (3), pp. 275-294 : 289

14. Piper mestonii F.M.Bailey — Fig. 4e, 5d, 7a–d

Piper mestonii F.M. Bailey (1889) 2; Chew (1972) 13; Spokes (2007) 236. — Type: A. Meston & F.M. Bailey (BRI;iso NSW n.v.), Harvey’s Creek, Russell River, Queensland, Australia.

Distribution — New Guinea, east to Milne Bay Province (Goodenough I.); also northern Australia. Apparently rare or absent from the Bismarck Archipelago; absent from the Solomon Is.

Habitat & Ecology — In forest, 0 –1000(– 3200) m altitude.

Notes — The highest-altitude collections I have seen are from the Owen Stanley Range: Hopkins 946, Mt Kenevi, 3200 m and Brass 4680, Murray Pass, 2840 m. In the Highlands Region (Simbu and Southern Highlands Provinces only) the species is known from just a few collections and attains only c. 2550 m (NGF 6389). Van Royen (1982) accepted P. mestonii as a member of the montane/subalpine flora, but I have seen no specimen that would confirm his stated uppermost altitude of 3500 m.

Peekel (1984: 124, f. 201) apparently records this species for two localities on the eastern side of New Ireland, under the synonym P. rueckeri C.DC. His description, especially of the fruit-spikes being spiny-tuberculate, does suggest P. mestonii , but his figure is inconclusive. I have seen no specimen from the Bismarck Archipelago myself, nor did Chew (1972, 1992) cite any.

Chew (1972, 1992) gave numerous synonyms based on types from New Guinea and Australia. The most salient of these is P. stenocarpum C.DC. , a higher-altitude form distinguished only by its short narrow leaves and smaller fruit.

In all but the most coriaceous leaves the nerves are narrowly and sharply prominent above. This, and the stipule usually being less than 1 cm long, help distinguish P. mestonii from glabrous members of the P. macropiper complex, where the nerves are usually rounded-prominent above and the stipules 1–2 cm long. In ripe fruits the surface of the fused ovaries has a coriaceous, nearly glossy character (Fig. 4e). The styles too are stiffened and are 0.3 –1(–2.5) mm long. The 2(–3) stigmas are usually short and broad (‘2-lipped’) but occasionally are recurved and elongated, each branch being almost 1 mm long (e.g., Carr 16262, Northern Province, Kokoda and Clemens 10525, Morobe Province, Markham Valley).

I have not been able to determine stamen number from any of the ten or so male specimens I have seen. However, in his description of P. stenocarpum Chew (1972: 17) states that its male flowers are “2-staminate, filaments much longer than anthers at maturity”.

Dowe & Broughton (2007) have elucidated the circumstances of the name’s publication.

See under P. versteegii for a comparison with that species.