Oleandra coriacea, Copel, 1912

Hovenkamp, Peter H. & Ho, Boon-Chuan, 2012, A revision of the fern genus Oleandra (Oleandraceae) in Asia, PhytoKeys 11, pp. 1-37 : 7-8

1. Oleandra coriacea Map 1 fig. 11 d-f

Oleandra coriacea Copel. J. Straits Branch Roy. Asiat. Soc. 63: 72. 1912. Type: MALAYSIA. Borneo:Moulton s.n.(SAR? not seen).

Description.

Rhizome with creeping parts unknown, aerial stems unbranched and rootless, 2-3 mm thick (when dry), not white waxy, in cross-section with a distinct sclerified peripheral sheath and few, scattered sclerified strands, phyllopodia in weak to distinct clusters of 4-6, short, usually less than 5 mm long. Scales persistently covering the rhizome, peltate, 5-70 × 0.5-1 mm, appressed (sometimes spreading), dark, shining with pale to brown margin and acumen, margin ciliate especially when young. Fronds monomorphic; stipe 1-1.5 cm long, without dark colouration, with up to 1 mm long glandular hairs and often small, appressed scales; lamina 13-30 × 1.2-3.3 cm, linear, base narrowly cuneate to rounded, apex acuminate to caudate with cauda to 1.5 cm, texture coriaceous; costa and veins on lower surface densely hairy with up to 1 mm long, acicular hairs, costa without dark colouration, with copious, conspicuous, 3-4 mm long pale to brown scales, upper surface more glabrous, mostly hairy on the costa only, with similar hairs and with less copious scales. Sori in a single more or less irregular medial row, separated from the costa by a 2-7 mm wide sterile zone, indusium distinct, c. 1.5 mm wide, most often glandular. Sporangial stalk with glands below the sporangium. Spores with coarse confluent ridges, areolae with short pointed excrescences, perispore hollow, with internal baculae, outer layer distinctly perforated.

Distribution.

Brunei, Indonesia: Kalimantan Timur; Malaysia: Sarawak.

E

cology.

Terrestrial in montane forest, mainly on ridges and in summit vegetation, 1100-2200 m.

Discussion.

Creeping and rooting parts of the rhizome are absent in all collections seen, but presumably present, as in Oleandra neriiformis . The lamina of Oleandra coriacea is indeed much more coriaceous than Oleandra neriiformis , and has copious large pale costal scales and long hairs especially on lower surface. The sori are consistently medial, with firm indusia that are often clearly glandular on their surface.

Figures

Map 1. Distribution of Oleandra coriacea (triangles), Oleandra musifolia (circles).

Figure 11. Oleandra neriiformis (a-c, g-m), Oleandra coriacea (d-f). a middle part of lamina, medial sori with indistinct indusia b entire lamina c lyrate lamina base with stipe articulation immediately below lamina base: Brass 2301 6 (New Guinea) d middle part of lamina, with conspicuous scales on midrib and sori with persistent indusia e entire lamina f lamina base with elongated stipe: Yahud et al SAR 88396 (Borneo) g entire lamina with costal sori h middle part of lamina, sori costal with persistent indusia i rounded lamina base with short stipe j whorl of short phyllopodia on aerial stem: Chew, Corner & Stainton 298 (Borneo) k middle part of lamina sori with inconspicuous indusium l rounded lamina base with short stipe m lamina: Copeland s. n. 29 jan 1933 (Philippines)., All views of lamina showing abaxial surface; all specimens L.