Sri Lanka has an immense wealth of plants. Everywhere one looks, there are green plants. According to the last enumeration, there are 3,154 species of flowering plants in Sri Lanka, with 348 species of ferns, 788 species of mosses and liverworts, and over 1,000 species of lichens. Nearly one in four flowering plant species is endemic to Sri Lanka. Apart from 894 species of endemic flowering plants, 49 species of ferns are also endemic to Sri Lanka.
However, recent surveys have shown that about 44% of flowering plants are threatened. Major areas covered in this program include a) taxonomic and biogeographical studies of the flora of Sri Lanka, b) preparation of the National red list for flora, c) sustainable of use of plants, d) factors affecting the conservation of flora of Sri Lanka including Invasive Alien Species, and e) restoration ecology.
Endemism in Sri Lanka shows a specific geographical pattern. The sightings or locations of the endemic flowering plants in Sri Lanka were obtained using records from the National Herbarium and reliable published ecological studies. The locations were plotted in a grid overlaid on a map of Sri Lanka using the GIS software Arc GIS 10. The grid of Sri Lanka consisted of 2847 cells each measuring 5 km x 5 km. There were 84,429 location records. The areas of endemism were identified by using the weighted endemism scores of grid cells and were classified by natural break method and geographic features.
High endemism was recorded for the wet zone of Sri Lanka. In Sri Lanka nine areas were identified where endemism was high (weighted endemism were between 0.7 - 2.5) and were tentatively named as endemic zones (Figure 1). The identified endemic zones are; Central Highlands, South Western Wet Zone, Northern Highlands, Eastern Highlands, Ritigala, Dolu kanda, Yala, Wilpattu and Jaffna. Within the nine endemic zones, there were regions with very high endemism and were called core endemic areas. The core endemic areas are Sinharaja, Adams Peak, Knuckles, Horton Plains and Kandy. The occurrence of endemic genera (Adrorhizon, Championia, Cyphostigma, Davidsea, Diyaminauclea, Doona, Hortonia, Leucocodon, Loxococcus, Nargedia, Phoenicanthus, Podadenia, Schumacheria, Schizostigma, Scyphostachys and Stemonoporus) were generally confined to the core endemic areas.
Panicum trichocladum K. Schum., a grass native to Tropical East Africa was first reported in Sri Lanka from Hanguranketha area around 2002. Distribution of this grass appears to be expanding in the country during the last decade. It is mostly seen along the roadsides forming a dense mat covering the ground. In some areas it is found inhabiting coconut estates, home gardens, cultivated areas and wastelands (Figure 1). Up to now, there are no serious investigations carried out to find out its distribution and invasive potential in Sri Lanka. Therefore, the main focus of this preliminary study is to find out the occurrence of this grass in relation to different climatic regions of Sri Lanka. In this study, natural distribution of P. trichocladum was measured by conducting an island wide field survey. The map of Sri Lanka was divided in to 2 km x 2 km grids laid over agro-ecological regions using Arc GIS software. The field survey was conducted starting from Hanguranketha along coordinal directions; North, South, East and West. Occurrences of P. trichocladum along the main roadsides of each direction were monitored and the presence and absence of the grass species were marked and recorded on the 2 X 2 km grids.
No occurrence of P. trichocladum was observed in the agro-ecological regions DL1, DL3, DL5, and WU3. P. trichocladum was present in all other agro-ecological regions visited. Among those agro-ecological regions where this grass is present, IM1, IM3, WM3 and WL1 showed the highest density compared to the other regions. It appears that this grass prefers wet areas in the low and mid country and the dry and cold areas are not invaded.
Clusia rosea (gal goraka) is a plant species having a highly efficient C4 photosynthetic pathway. This plant, native to Central America, has become a nationally significant invasive plant in wet sub-montane Sri Lanka. However, Clusia rosea has the ability to prosper in marginal landscapes such as heavily rocky areas due to the strong and efficient root system belongs to the plant. Success rate of grafted Garcinia quaesita (goraka) and G. mangostana (Mangosteen) up to fruiting stage are low due to poor support in nutrient supply by the root stock of their own species. An experiment was conducted at Hapugastenne estate, Maskeliya, to ascertain the possibility of using C. rosea as a rootstock in grafting of crop plants such as Garcinia quaesita (goraka) and G. mangostana (Mangosteen) in the Clusiaceae family to which Clusia also belongs.
Grafting of both G. quaesita and G. mangotana was carried out using C. rosea as the rootstock. 55% of Mangosteen and 67% of goraka grafts were alive and healthy at the beginning of acclimatization. However, casualty rate increased. as time passed. Only 32% of Mangosteen survived after one month of acclimatization. Survival rate was seen highest (48 %) in unbranched, smaller (5-10 cm long) goraka scions with 4-6 fully opened leaved twigs.