The distribution and habitats of the Pteris fauriei complex in Taiwan

Polyploidization is a significant mode of speciation in plants. Polyploids ofeten occupy habitats different from those of their diploid parents. In Taiwan, two varieties of Pteris fauriei, one diploid and one triploid, have been identified. The number of spores per sporangium and the size of spores are reliable indicators of ploidy. Diploid P. fauriei have 64-spore sporangia and the spores are significantly smaller than spore of triploid plants, which have 32-spore sporangia. Base on these findings, the distribution and habitats of the two cytotypes in Taiwan are characterized from both living plants and herbarium specimens. Altogether, 516 living plants from 32 populations and 76 herbarium specimens were analyzed. In general. diploid occur in warmer habitats than triploid plants. Diploid plants distribute widely in Taiwan and nearby islands, but not occur in central Taiwan or in the Matsu islands. In contrast, triploid plants are not found in southern Taiwan or in islands west of the central Taiwan. In nortehern Taiwan and on the west-central islands, diploids grow most often in exposed sites and grasslands. However, in southern Taiwan and islands Lanyu and Lutao, diploids also occur in woodlands. Triploids are were restricted to grassland and woodlands habitats in Taiwan, but grow in exposed sites, grassland and woodland habitats in Matsu islands. In general, triploids grow at higher elevations than the diploids.