Piper celtidiforme Opiz

Gardner, R. O., 2013, Piper (Piperaceae) in New Guinea: the climbing species, Blumea 57 (3), pp. 275-294 : 283

6. Piper celtidiforme Opiz — Fig. 4a

Piper celtidiforme Opiz (1828) 152;Quisumb.(1930) 177,pl.22;R.O. Gardner (2006) 580; (2010) 11. — Type: Haenke s.n. (holo PR n.v.), Luzon.

Piper seemannianum C.DC (1866) 164, syn. nov. — Type: Barclay 3515 (holo BM, image!), New Ireland.

Distribution — Philippine Is., New Guinea including Bismarck Archipelago, Solomon Is.; probably also Celebes.

Habitat & Ecology — In forest, 0 – 2000(– c. 2700) m altitude.

Notes — Recognized by its chartaceous, ovate-oblong, nearly glabrous (never coarsely hairy), pinnate-veined leaves. The usual red subepidermal mottling is often sufficient to give the whole leaf a brownish red cast.

Male P. celtidiforme has uniquely-formed stamens (see ‘Spot Characters’; Gardner 2006: f. 5). The female flowers are very distinctive too, their narrow, smooth-surfaced stigmas being seen elsewhere only in P. versteegii . These fragile structures are mostly lost as the fruit ripens and the fruitlet apex then just shows a ring of eroded tissue. Also, female specimens sometimes have a granulose papillosity around the base of the stigmas, making a whitish band conspicuous enough to be visible to the naked eye (Fig. 4a). Less frequently, the central third or so of a female’s bract-heads also bears a patch of granulosity. The specimen NGF 34383 (West New Britain, Fulleborn Harbour, 50 m, A) is unusual in having 4 – 6 very short, broadly ovate, strongly papillose stigmas.Also, the stigmas of Takeuchi 15243 (Morobe Province, Tabare (Tabili) River, sea level, A) have the usual narrow character but are also notably papillose. Neither though seems otherwise unusual for P. celtidiforme .

The occurrence on Celebes seems likely, since de Candolle (1923: 278) synonymized one of his names from there, P. sinkojan C.DC. (as ‘ P. sinkgian ’) with P. corylistachyon C.DC. of the Philippines, and the latter has, correctly I believe, been placed by Quisumbing (1930: 177) under P. celtidiforme . De Candolle never saw the PR holotype of P. celtidiforme – as the annotation-free photograph of Quisumbing (1930, pl. 22) proves – and in his 1923 account he treated the species just as a ‘ Eupipera non satis nota ’.

For the Bismarck Archipelago Peekel (1984: 129) says, under P. singkojang [sic]: “Easily the most common species of pepper in the region; widespread on the trunks of forest trees. The red fruit-spikes, erect from horizontal twigs on the tree-trunks, are particularly conspicuous. Where the plants find little support, the stems and branches spread widely over the ground and the densely-set leaves form there a regular turf. The leaves of such plants are usually smaller and their bases deeply cordate or reniform”.