The varieties of Bauhinia pottsii G. Don in Thailand (Leguminosae-Caesalpinioideae)

Abstract

Bauhinia pottsii G. Don, B. subsessilis Craib, B. velutina (Wall. ex Benth.) Baker, B. mollissima (Wall.) Prain, and B. decipiens Craib were recently recognized as five varieties of Bau- hinia pottsii G. Don. They grow naturally in southern Myanmar, Thailand, Indochina and the Malay Peninsula. Bauhinia pottsii var. decipiens (Craib) K. Larsen & S. S. Larsen is endemic to Thailand and known only from the type collec- tion, so it was omitted from this study. Quanti- tative and qualitative morphological characters were examined in 200 specimens using multivar- iate and univariate analyses to determine the taxonomic relationship among the four. Some variation in qualitative characters was found between the varieties which separated them as previously defined in Flora of Thailand. Forty- three quantitative characters were subjected to cluster analysis to allow an objective classification into groups. The groups were subsequently eval- uated by a canonical discriminant analysis. It was found that these characters collectively support the four varieties as defined by qualitative char- acters. However, the close relationship of varieties mollissima (Wall. ex Prain) K. Larsen & S. S. Larsen and velutina (Wall. ex Benth.) K. Larsen & S. S. Larsen is observed. The linear discriminant function has an overall rate of 98.5% correct classification and is useful for variety classifica- tion. Among quantitative characters, petal-claw length and ovarystalk length together with some qualitative characters are useful for key construc- tion to separate the four varieties.