Cyathea sledgei

A new tree fern species from Sri Lanka has been identified and named from the specimens collected from two wet zone forests by University of Peradeniya Postgraduate Institute of Agriculture R H G Ranil who has been studying the ferns since his student days.

This new species is scientifically named as Cyathea sledgeRanil et al. and has been named in honour of late W Arthur Sledge (1904-1991) of the Department of Botany in the University of Leeds for his immense contribution to the fern flora. This species is described in a paper published in the Fern Gazette Volume 18(7) of 2010,co-authored by R H G Ranil, Dr D K N G Pushpakumara, Dr T Janssen, Dr C R Fraser-Jenkins and Dr D S A Wijesundara.

The species was first collected from Kanneliya Forest Reserve in January 1951 by Dr W A (Arthur) Sledge and Dr F Bellard. They considered it as sterile hybrid between the two endemic Sri Lankan species that were seen in the vicinity, namely Cyathea hookeri and Cyathea sinuata. The only reason why it was thought a hybrid was that it has characteristics intermediate to the two species and that they thought it was sterile. It was overlooked in subsequent works as no one has subsequently made any references to it in any subsequent literature on the tree ferns occurring in Sri Lanka.

Ranil found it (rediscovered) in Kanneliya in 2003 and thereafter from the Sinharaja National Heritage Wilderness Area in 2008. In both these localities it has been seen in the same areas where the other two species are also seen. The paper state that the authors have observed it to be fertile and producing spores that germinate and have been even able to germinate the spores in controlled conditions in the National Botanical Gardens, Peradeniya.

The tree fern has been able to form populations with the same characteristics and has hence presumed to be a new species hitherto overlooked. Although it was presumed as a hybrid due to it having features that are seen in the two species,there have been no studies carried out to verify this possibility.

This tree fern has a thin unbranched and upright trunk that grows to about 95 cm to 135 cm in height and only 1.2 to 1-7 cm in diameter.

The trunk is covered entirely with the bases of fallen leaves. At the end of the trunk is a clump of about 18 to 26 leaves which are 60-90 cm in length and 3.7 to 5.1 cm in width.

It is found in stream-sides and road-side banks in both localities where the other two are also found at altitudes between 320-450 meters. The species Cyathea hookeri is very rare and has also been found only from Sinharaja and Kanneliya forests.