Oleandra cumingii

Hovenkamp, Peter H. & Ho, Boon-Chuan, 2012, A revision of the fern genus Oleandra (Oleandraceae) in Asia, PhytoKeys 11, pp. 1-37 : 8-9

2. Oleandra cumingii Map 2

Oleandra cumingii J.Sm., J. Bot. (Hooker) 4: 413. 1842. C.Presl, Epimel. Bot.: 41. 1851. Fée, Mém. Foug., 5. Gen. Filic.: 304. 1852. Hook., Sp. Fil.: 158. 1862. Baker, Syn. Fil. (Hooker & Baker): 303. 1868. Copel., Polypod. Phil. Isl.: 49. 1905. Copel., Fern Flora of the Philippines: 184. 1958. Ching, Fl. Reipubl. Popularis Sin. 2: 324. 1959. X.C.Zhang, Ching Mem. Vol.: 91. 1999. Type: PHILIPPINES. Luzon: Cuming 60. (holotype: K; isotypes: B, BM, SING, US*),

Oleandra macrocarpa C.Presl, Epimel. Bot.: 41. 1851. Fée, Mém. Foug., 5. Gen. Filic.: 304. 1852. Holttum, Novit. Bot. Inst. Horto Bot. Univ. Carol.: 43. Type: PHILIPPINES. Luzon: Cuming 60 p.p. (Holotype: PRC, teste Holttum; isotypes: B, BM, K, SING, US*).

Oleandra chinensis Hance, Ann. Sci. Nat. (Paris) 18: 238. 1862. Type: CHINA. Guangdong: Si Chu Shan, Parry s.n., herb. Hance 9408 (holotype: K; isotype BM).

Oleandra scandens Copel., Philipp. J. Sci. 46: 218. 1931., Fern Flora of the Philippines: 184. 1958. Type: PHILIPPINES. Baguio: Elmer 6513 (holotype: US*).

Oleandra intermedia Ching, Bull. Fan Mem. Inst. Biol. 11: 187. 1931. Ching, Fl. Reipubl. Popularis Sin. 2: 323. 1959. X.C.Zhang, Ching Mem. Vol.: 92. 1999. Type: CHINA. Yunnan: Henry 9484c (holotype: K; isotypes: B, BM, MO*, PNH, US*).

Oleandra cumingii var. longipes Hook., Sp. Fil.: 158. 1860. Oleandra longipes Ching, Lingnan Sci. J. 12: 158. 1933. Type: BIRMA. Mergui: Parish 59 (holotype: K).

Oleandra cantonensis Ching, Fl. Reipubl. Popularis Sin. 2: 324, 378. 1959. Type: CHINA. Guangdong: Canton, Peiyinshan,.Y. Liang 60252 (holotype: PE).

Oleandra yunnanensis Ching, Fl. Reipubl. Popularis Sin. 2: 325. 1959. Type: CHINA. Yunnan: anon. s.n. (holotype: PE).

Oleandra guangxiensis S.L. Mo & Y.C. Zhong, Guihaia 7: 289. 1987. Type: CHINA. Giangxi: Damingshan, Guangxi Forest ecology group 84422 (holotype: IBY, not seen; isotype: PE).

Description.

Rhizome short- to long creeping, 3-8 mm thick, sometimes white waxy in the older parts, little branched and not forming extensive stands, in cross-section with or without scattered sclerified strands; roots scattered, sometimes with unbranched aerial parts; phyllopodia scattered or more or less tufted, (1-)3-10 cm long. Scales persistently covering the rhizome, peltate, 4-9 × 0.5-1.5 mm, appressed, acumen with dark center and lighter acumen and margin, margin ciliate especially when young. Fronds monomorphic, stipe 2-12 cm long, without dark colouration, glabrous or hairy with catenate to acicular up to 2 mm long hairs, lamina 12- 40 × 2-4.5 cm, base narrowly cuneate to truncate, apex acute to long-acuminate, texture thin-chartaceous, both surfaces and margin with catenate or acicular hairs 0.2-1 mm long, usually more densely on lower surface, costa without dark colouration, on lower surface without or with few, pale to dark scales. Sori close to or scattered up to 2 mm from the costa, indusium distinct, 1-2 mm wide, densely hairy with short or long hairs. Sporangial stalk with glands below the sporangium. Spores with broad or narrow confluent ridges, surface variably ornamented with small pustules to narrow spines, perispore hollow, with internal baculae, outer layer not or finely perforated, sometimes fissured along the ridges.

Distribution.

China: Yunnan, Guangdong, Guangxi, Guizhou; Laos; Thailand (Peninsular); Malaysia: Peninsular Malaysia; Indonesia: Flores; Timor Leste; Philippines: Luzon.

Ecology.

Terrestrial or on rocks, cliffs and roadsides in open forest, sea level to c. 1200 m.

Discussion.

Contrary to Holttum (1968a), Oleandra cumingii J. Sm. is not a nomen nudum, but provided with an adequate diagnosis. Cuming 60 is distributed in several herbaria with many duplicates, and it is impossible to tell which ones should be considered isotypes of Oleandra cumingii and which ones of Oleandra macrocarpa .

Oleandra cumingii is a variable assemblage of fairly widely scattered forms, in many characters intermediate between Oleandra undulata and Oleandra musifolia . From Oleandra undulata it can be distinguished by the more narrowly elongated, appressed rhizome scales with a more or less thickened costa in the acumen, and by the often hairy upper surface of the lamina. From Oleandra musifolia , Oleandra cumingii differs in the elongated phyllopodia and the distinctly tomentose indusia and lower surface of the lamina. The differences with either species, however, are often slight and bridged by specimens with an intermediate character combination. This may indicate that Oleandra cumingii is a hybrid or a hybrid swarm between the two other species, but failing positive evidence for that interpretation, we prefer to regard it here as a separate species.

Figures

Map 2. Distribution of Oleandra cumingii (squares), Oleandra undulata (triangles), Oleandra wallichii (circles).