Cyathea decrescens Mett. ex Kuhn

Janssen, Thomas & Rakotondrainibe, France, 2008, A revision of the indusiate scaly tree ferns (Cyatheaceae, Cyathea subgen. Alsophila sect. Alsophila) in Madagascar, the Comoros and the Seychelles, Adansonia (3) 30 (2), pp. 221-376 : 244-245

publication ID

https://doi.org/ 10.5281/zenodo.5190422

persistent identifier

https://treatment.plazi.org/id/03D3163A-FF93-FFAB-3CEB-4E69110E6ACB

treatment provided by

Carolina

scientific name

Cyathea decrescens Mett. ex Kuhn
status

 

5. Cyathea decrescens Mett. ex Kuhn View in CoL

REMARKS

Varieties of this taxonomically difficult species are defined here primarily based on the degree of lamina dissection. Characters proposed in previous treatments (Tardieu-Blot 1951), such as pinnule shape and axial indument, are not sufficiently discriminative within this taxonomic complex. Indurated, shiny black and arched petiole scales are common to all varieties of this species.

KEY TO THE VARIETIES OF CYATHEA DECRESCENS View in CoL

1. At least the first five proximal pinnule pairs free, sessile to petiolulate, the following pinnules progressively adnate to the costa, adnate for their entire width only from above the middle of the pinna ............................................................................ 5d. var. quadrata View in CoL

— At most the first two proximal pinnule pairs free, sessile, all other pinnules broadly adnate to the costa for their entire width ............................................................................... 2

2. Pinnules 2.5-3.5 × 0.3-0.4 cm, spaced by at least their width; trunk 8-10 cm in diameter ............................................................................................................. 5a. var. cristata View in CoL

— Pinnules (1-)1.5-2 × 0.4-0.6(-0.8) cm, spaced by less than their width; trunk up to 6 cm in diameter ................................................................................................................. 3

3. Aphlebia present; petiole scales strongly indurated and arched, not bullate .................... .......................................................................................................... 5b. var. decrescens View in CoL

— Aphlebia absent; petiole scales less strongly indurated and only slightly arched, with a slightly bullate base ................................................................. 5c. var. manongarivensis View in CoL

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