本研究藉由葉綠體DNA之trnF-trnL基因間區間序列比較已知八種杜鵑之親緣關係，八種杜鵑trnF-trnL基因間區間序列於排序後之全長爲460個鹼基對，此區域內有16個變異處，其中10個可用以判定親緣關係。核酸序列以MEGA軟體進行neighbor-joining及parsimony樹狀親緣關係圖的分析，均可得到三個主要之分群。第一群包含玉山杜鵑、紅星杜鵑、森氏杜鵑、南湖杜鵑及台灣杜鵑，台灣杜鵑可自此群單獨分出爲一群。第二群爲金毛杜鵑及烏來杜鵑。西施花則單獨獨立爲第三群，而與其他七種杜鵑有較遠之親緣關係。本研究之主要結果爲藉由分子證據顯示玉山杜鵑、森氏杜鵑、紅星杜鵑及南湖杜鵑之間有非常接近的親緣關係，而此結果亦與形態的證據吻合。
Phylogenetic relationships among 8 species of Rhododendron were derived from sequence comparisons of the chloroplast trnF-trnL intergenic spacer region. Aligned sequences of the 8 Rhododendron taxa were 460 base pairs. The region contained 16 variable sites, of which 10 were phylogenetically informative. Neighbor-joining and parsimony analyses were conducted using MEGA. Identical topology with 3 major clades was obtained from parsimony and neighbor-joining trees. Clade 1 consisted of R. pseudochrysanthum, R. rubropunctatum, R. morii, R. hyperythrum, and R. formosanum. Rhododendron formosanum was sister to the other 4 species in the clade 1. Clade 2 consisted of R. oldhamii and R. kanehirai. Rhododendron ellipticum formed clade 3 and was basal to all other Rhododendron species. Close phylogenetic relationships among R. pseudochrysanthum, R. morii, R. rubropunctatum, and R. hyperythrum based on the cpDNA sequences agreed with those derived from morphological characters.
