Botany and Taxonomy of Tea (Camellia sinensis, Theaceae) and Its Relatives

Tea plants, Camellia sect. Thea (Theaceae), are popular beverage sources worldwide. Camellia sect. Longissima is treated as a new heterotypic synonym of sect. Thea. The taxonomy of tea plants was reviewed to contain 11 natural species and seven infraspecific taxa, including C. costata, C. crispula, C. crispula var. multiplex, C. fangchengensis, C. gymnogyna, C. kwangsiensis, C. kwangsiensis var. kwangnanica, C. leptophylla, C. longissima, C. ptilophylla, C. sinensis, C. sinensis f. formosensis, C. sinensis var. assamica, C. sinensis var. dehungensis, C. sinensis var. pubilimba, C. tachangensis, C. tachangensis var. remotiserrata, and C. taliensis. Their nomenclatural types, diagnostic character states, phenology, and natural geographic distribution are summarized in this chapter. The contents of chemical components, especially caffeine and tea polyphenols, are listed where available and a key to the taxa of sect. Thea is provided. Camellia flosculora, C. grandibracteata, C. pubicosta, and C. sealyana are excluded from sect. Thea. Both robust phylogenetic trees of sect. Thea and thorough field investigations are needed to yield a natural and satisfactory systematics of tea plants.