Variation of Three Co-occurring Taxa of the Genus <i>Cyathea</i> in Singharaja and Kanneliya Lowland Rain Forests of Sri Lanka

The objective of this study was to identify variation of three co-occurring taxa of the genus Cyathea at Singharaja and Kannelliya forests. Fifty three mature individuals were sampled from both forests for morphological variation, reproductive biology and cytological investigations. Twenty five morphological characters were initially assessed and data were analyzed for 10 characters by principal component analysis (PCA) and cluster analysis. Based on these, three taxa studied were identified as Cyathea sinuata Hook. & Grev., Cyathea hookeri Thw. and the hybrid between the two parents. Both parents and the hybrid were cytologically similar with meiotic chromosomes of n=69. Reproductive biology of the three taxa were similar in terms of spore germination, gametophyte and sex organ development. However, the hybrid did not produce the sporophyte indicating it may be sterile. DOI: 10.4038/tar.v21i2.2595 Tropical Agricultural Research Vol. 21(2): 134-146 (2009)