| Popis: |
Cycads are a primitive group of living seed plants which is dignified as an indispensable element revealing evolutionary affinities of present day plants. However, cycads in Sri Lanka have received the least scientific attention so far. Aiming to identify the different cycad taxa present in Sri Lanka and to find out their vegetative and reproductive morphological features of taxonomic significance, an island wide survey of Sri Lankan cycads was conducted. During the field survey, vegetative morphological features (both qualitative and quantitative) were recorded in 181 mature individuals however, reproductive structures were available in 60 of these. These were identified according to more recent, validly published circumscriptions of given taxa. Cycas species in Sri Lanka represent both subsection Cycas and subsection Rumphiae of the section Cycas. This study further reveals the occurrence of both Cycas circinalis L. andC. nathorstii J. Schuster of the subsection Cycas in Sri Lanka. Accordingly, taxonomically useful morphological features in distinguishing different Cycas taxa in Sri Lanka were identified and further descriptions of the two species populations identified in Sri Lanka have been made. However, the individuals examined of the subsection Rumphiae showed a wide but consistent variation indicating the presence of more than a single species in this subsection and, need further investigations to describe these to the species level. Further, molecular characterization of Sri Lankan Cycas species benefits more in identifying different Cycas species of Sri Lanka and their intermediate forms and, in describing their biogeographic affinities. These studies are currently being conducted at the University of Peradeniya, Sri Lanka. Ceylon Journal of Science (Bio. Sci.) 44 (1) : 13-23, 2015 |
