Species diversity and reproductive phenology of Podostemaceae in Na Hahaeo District, Loei Province, Northeastern Thailand.

Abstract

The species composition of Podostemaceae was studied in Loei, northeastern Thailand from November 2009 to July 2010 by extensive surveying in the rapids and waterfalls inside and outside of national parks, wildlife sanctuaries and protected areas. The samples collected are classified into 2 subfamilies, which are Tristichoideae and Podostemoideae. The former contains 2 genera and 3 species, Dalzellia kailarsenii, Terniopsis sp. 1, Terniopsis sp. 2. The latter has 4 genera and 9 species, Hanseniella heterophylla, Hydrobryum japonicum, Hydrobryum loeicum, Hydrobryum tardhuangense, Hydrobryum vientianense, Hydrobryum sp. 1, Hydrobryum sp. 2, Polypleurum sessile, Thawatchaia trilobata. The highest number of species occurs in Hydrobryum with 6 species following by Terniopsis with 2 species. The other four genera have one species each. Based on morphological and molecular analyses revealed that 2 species of the genus Hydrobryum are new and 2 taxa of Terniopsis are also new species. Polypleurum sessile and Thawatchaia trilobata are new recorded in Loei province. The result from this study indicates that the genus richness is relatively high in Loei province which encompasses 60% of the total number of genera (10) in Thailand. The plants in vegetative phase are completely submersed in swiftly running water during a warm wet season (May-October). The plants flower and set fruits and seeds when exposing to air during water level drop in a cool dry season (November- February).