Blechnum finlaysonianum
Content
Distribution
Asia-Tropical, many areas of SE Asia, from Indochina extending southwards present
Malesia: Throughout. Outside Malesia: widespread (but usually not common) in many areas of SE Asia, from Indochina extending southwards.
Notes
1. In some of its growth forms this species is easily confused with B. orientale, especially when the latter is growing under luxuriant conditions. Herbarium specimens of B. finlaysonianum with narrow pinnae may be difficult to separate from B. orientale, especially if fragmentary or incomplete. The most useful but not infallible diagnostic character for separating these two species is the gradual tapering of the pinnae in B. orientale against the broader sometimes non-tapering pinnae of B. finlaysonianum which reduce abruptly to an attenuate apex. Another useful character is the tendency in B. finlaysonianum for the pinnae towards the frond base to be shortly petiolate and narrowly cuneate at their point of attachment to the rhachis.
2. The juvenile stages of B. finlaysonianum are distinctive and very different from those of B. orientale. While the very earliest post-prothallial stages of B. finlaysonianum have not been seen, the earliest fronds with mature texture are often entire and narrowly elliptic, tapering at both ends and range in size from 2-5 by 1 cm in the very young stages, to 30 by 5 cm, with a stipe of 2-3 cm. Later juvenile fronds are lobed, with 2-6 sessile lateral pinnae; wherever a pinna arises the main entire leaf is dissected back to its rhachis at that point. The lobes are usually conspicuously decrescent on their basiscopic margins and the base of the lamina sometimes narrows to a thin wing down the rhachis with lobes progressively further apart towards the stipe. The stipe, although variable in length, is proportionately longer than that of the mature frond. Both stipe and rhachis are grooved and pale on the upper (adaxial) surface and dark purplish black on the semi-terete undersurface. This pigmentation of the rhachis usually extends to near the lamina apex.
3. Sometimes the entire and the lobed fronds of B. finlaysonianum may be confused with sterile fronds of B. melanocaulon subsp. melanocaulon. In this regard both species resemble the juvenile stages of the tropical South American B. volubile (Salpichlaena volubilis); presumably on the basis of this similarity, Fée (1852: 79) placed the species B. finlaysoniana into the genus Salpichlaena.
4. In terms of ecological preferences, B. finlaysonianum invariably grows in shady or semi-shaded forests, while B. orientale is more frequent in semi-shaded to full sun habitats (see notes under that species).
5. A possibly distinct taxon from the Philippines (M.G. Price 2776, M.G. Price & Hernaez 426) is provisionally included in B. finlaysonianum. The mature fronds (sterile and fertile) differ from those of typical B. finlaysonianum in being much narrower and tapering evenly to the apex rather like those of B. orientale. However, the juvenile fronds which range from entire to pinnatifidly lobed, are similar to those of B. finlaysonianum. Other differences when compared with B. orientale are the relatively few well-spaced pinnae and the strongly decurrent pinnae bases especially towards the frond apex; in B. orientale the pinnae are numerous and the pinna bases are usually truncate. The mature fronds of the taxon do not match those of B. whelanii which has serrate margins, relatively widely spaced veins and a wider sorus occupying more of the abaxial face of the fertile pinnae.
6. Blechnum finlaysonianum var. amboinensis Rosenst. nomen? Annotation on specimen at L (Amboina 471) det. by Rosenstock. This specimen is doubtfully distinct, the pinnae are narrower than average and tend to taper to their apices more evenly (see also note 5 on Philippine specimens). See also discussion by Morton ().
7. For typification of Blechnopsis latifolia see Holttum ().
2. The juvenile stages of B. finlaysonianum are distinctive and very different from those of B. orientale. While the very earliest post-prothallial stages of B. finlaysonianum have not been seen, the earliest fronds with mature texture are often entire and narrowly elliptic, tapering at both ends and range in size from 2-5 by 1 cm in the very young stages, to 30 by 5 cm, with a stipe of 2-3 cm. Later juvenile fronds are lobed, with 2-6 sessile lateral pinnae; wherever a pinna arises the main entire leaf is dissected back to its rhachis at that point. The lobes are usually conspicuously decrescent on their basiscopic margins and the base of the lamina sometimes narrows to a thin wing down the rhachis with lobes progressively further apart towards the stipe. The stipe, although variable in length, is proportionately longer than that of the mature frond. Both stipe and rhachis are grooved and pale on the upper (adaxial) surface and dark purplish black on the semi-terete undersurface. This pigmentation of the rhachis usually extends to near the lamina apex.
3. Sometimes the entire and the lobed fronds of B. finlaysonianum may be confused with sterile fronds of B. melanocaulon subsp. melanocaulon. In this regard both species resemble the juvenile stages of the tropical South American B. volubile (Salpichlaena volubilis); presumably on the basis of this similarity, Fée (1852: 79) placed the species B. finlaysoniana into the genus Salpichlaena.
4. In terms of ecological preferences, B. finlaysonianum invariably grows in shady or semi-shaded forests, while B. orientale is more frequent in semi-shaded to full sun habitats (see notes under that species).
5. A possibly distinct taxon from the Philippines (M.G. Price 2776, M.G. Price & Hernaez 426) is provisionally included in B. finlaysonianum. The mature fronds (sterile and fertile) differ from those of typical B. finlaysonianum in being much narrower and tapering evenly to the apex rather like those of B. orientale. However, the juvenile fronds which range from entire to pinnatifidly lobed, are similar to those of B. finlaysonianum. Other differences when compared with B. orientale are the relatively few well-spaced pinnae and the strongly decurrent pinnae bases especially towards the frond apex; in B. orientale the pinnae are numerous and the pinna bases are usually truncate. The mature fronds of the taxon do not match those of B. whelanii which has serrate margins, relatively widely spaced veins and a wider sorus occupying more of the abaxial face of the fertile pinnae.
6. Blechnum finlaysonianum var. amboinensis Rosenst. nomen? Annotation on specimen at L (Amboina 471) det. by Rosenstock. This specimen is doubtfully distinct, the pinnae are narrower than average and tend to taper to their apices more evenly (see also note 5 on Philippine specimens). See also discussion by Morton ().
7. For typification of Blechnopsis latifolia see Holttum ().