Abstract
Camellia flavida is an endangered species of yellow camellia growing in limestone mountains in southwest China. The current classification of C. flavida into two varieties, var. flavida and var. patens, is controversial. We conducted a genetic analysis of C. flavida to determine its taxonomic structure. A total of 188 individual plants from 20 populations across the entire distribution range in southwest China were analyzed using two DNA fragments: a chloroplast DNA fragment from the small single copy region and a single-copy nuclear gene called phenylalanine ammonia-lyase (PAL). Sequences from both chloroplast and nuclear DNA were highly diverse; with high levels of genetic differentiation and restricted gene flow. This result can be attributed to the high habitat heterogeneity in limestone karst, which isolates C. flavida populations from each other. Our nuclear DNA results demonstrate that there are three differentiated groups within C. flavida: var. flavida 1, var. flavida 2, and var. patens. These genetic groupings are consistent with the morphological characteristics of the plants. We suggest that the samples included in this study constitute three taxa and the var. flavida 2 group is the genuine C. flavida. The three groups should be recognized as three management units for conservation concerns.
Highlights
Camellia (Theaceae) species with yellow flowers, known as yellow camellia, grow in parts of south China and north Vietnam
Yellow camellia frequently grows in primary forests, as understory shrubs or small trees, but they can be found among secondary forests and shrubs that have suffered from deforestation
Ye and Xue (2013) studied the morphological characteristics of the flowers, fruits, seeds, and leaves of the taxa that had been reduced to C. flavida, and the results suggested that (1) C. ptilosperma and C. longruiensis should be considered synonyms of C. longgangensis, (2) C. longgangensis var. patens and C. multipetala should be classified as a synonym of C. quinqueloculosa, and (3) C. wumingensis is an independent species (Table 1)
Summary
Camellia (Theaceae) species with yellow flowers, known as yellow camellia, grow in parts of south China and north Vietnam. Studies have reported 10–16 species in China (Chang and Ren, 1998; Ming and Bartholomew, 2007). These plants are mainly distributed in Guangxi, with only a few reaching Guizhou and Yunnan Province (Chang and Ren, 1998; Liang, 2007). Most species of yellow camellia in China have restricted distributions. Some species grow in calcareous soil, and others are found in acidic soil. No known species naturally grows in both calcareous and acidic soil. Calcareous species are usually found at the bottom of depressions or on slopes in areas with high humidity and shade (Su and Mo, 1988; Su, 1994)
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