Periwinkle [Catharanthus roseus (L.) G. Don.], a member of the Apocynaceae family, is endemic to Madagascar. This herbaceous plant grows to 80 cm high and blooms continuously year-round with pink, purple, or white flowers (Hogan, 2003). A program to conserve and protect this species has been established, because it produces secondary metabolites such as terpenoid indole alkaloids that may be used to treat cardiac diseases and certain tumors in mammals (Favali et al., 2004).
Catharanthus roseus has become pantropical by escaping from cultivation and naturalizing in many other regions (Levy, 1981). The flower is functionally close to cleistogamous with pollination limited by the foraging behavior of insects, and thus seed production is expensive (Miyajima, 2004). Breeding efforts have resulted in many new forms and cultivars, making them valued as bedding plants and flowering potted plants (Armitage, 2001). However, few double-flowered periwinkle cultivars are available on the markets.
Flower doubleness may increase the horticultural value of the plant. ‘Taoyuan No. 1 Rose Girl’ was selected from a cross between a double-flowered mutant identified from a self-pollinated ‘Pacifica Polka Dot’ population and a line derived from selfing ‘Titan Burgundy’. The horticultural traits of this newly released cultivar are described below.
ArmitageA.M.2001Armitage’s manuals of annuals biennials and half-hardy perennials. Timber Press Portland OR
FavaliM.MuesttiR.BenvenutiS.BianchiA.PressaccoL.2004Catharanthus roseus L. plants and explants infected with phytoplasmas: Alkaloid production and structural observationsProtoplasma2234551
HoganS.2003Flora: A gardener’s encyclopedia. Timber Press Inc. Portland OR
LevyA.1981Catharanthus roseus p. 166–168. In: Halevy A.H. (ed.). CRC handbook of flowering. Vol. II. CRC Press Boca Raton FL
Royal Horticultural Society2007The Royal Horticultural Society’s colour chart. 5th Ed. Royal Hort. Soc. London UK