Oleandra werneri, Rosenst, 1908

Hovenkamp, Peter H. & Ho, Boon-Chuan, 2012, A revision of the fern genus Oleandra (Oleandraceae) in Asia, PhytoKeys 11, pp. 1-37 : 19-20

9. Oleandra werneri Map 5

Oleandra werneri Rosenst., Repert. Spec. Nov. Regni Veg. 5: 40. 1908. Copel., Philipp. J. Sci. 73: 347. 1940. R.M.Tryon, Rhodora 102: 433, fig. 3. 2001. Type. INDONESIA. New Guinea: Werner 12(lectotype: L, "Rosenstock 28", here selected; isotype: B).

Oleandra dimorpha Copel., Philipp. J. Sci. 60: 111. 1936. M.Kato, J. Fac. Sci. Univ. Tokyo, Sect. 3, Bot. 14: 239. 1989. Type. SOLOMON ISLANDS. San Christoval: Brass 2916 (holotype: MICH).

Description.

Rhizome with main stems creeping, scrambling or pendent, 2-3 mm thick, white waxy in the older parts, sparsely rooting, mostly terete when dry, bearing scattered short, usually less than 5 mm long phyllopodia, phyllopodia on aerial parts more closely together but not densely clustered; all parts in cross section with a peripheral sclerified sheath and scattered sclerified strands. Scales covering the rhizome, peltate, 3-4 × 0.5-1 mm, somewhat squarrose, with dark center and lighter margin and acumen, margin ciliate especially when young. Fronds strongly dimorphic, stipe 0.5-2.5 cm, without dark colouration, especially upwards with up to 2 mm long hairs; lamina chartaceous; fertile 27-56 × 0.5-1 (-1.7) cm, base and apex narrow, sterile 17-30 × 2.2-5.7 cm, base mostly cuneate, apex distinctly 2-3.5 cm caudate; costa and lamina on lower surface glabrous or with up to 2 mm long hairs, costa without dark colouration, like the stipe with up to 2 mm long brown scales. Sori in a single row on both sides of the costa, indusium firm, 1-3 mm wide, glabrous. Sporangial stalk with glands below the sporangium. Spores with coarse confluent ridges, areolae with short pointed excrescences, perispore hollow, with internal baculae, outer layer not or hardly perforated.

Distribution.

Indonesia (Maluku, Papua); Papua New Guinea; Vanuatu.

Ecology.

Commonly epiphytic, on trunks or in crowns, less often terrestrial or on rocks, erect, scrambling or pendent, in various types of forests, most frequently in montane or mossy forests, on ridges, up to c. 2000 m.

Discussion.

As in Oleandra neriiformis , rhizome morphology is probably more complicated than can be inferred from the mostly aerial unbranching parts making up most of the collected material.

Hairiness is very variable, and while there is no sharp distinction between hairy and glabrous forms, it is noteworthy that hairy forms tend to occur at especially the Western extreme of the distribution area, with less hairy forms near the Eastern extreme and glabrous forms mostly on the mainland of New Guinea.

Figures

Map 5. Distribution of Oleandra vulpina (triangles), Oleandra werneri (circles).