Madagascar rosy periwinkle

Appearance

It is an evergreen subshrub or herbaceous plant growing 1 m tall. The leaves are oval to oblong, 2.5–9 cm long and 1–3.5 cm broad, glossy green, hairless, with a pale midrib and a short petiole 1–1.8 cm long; they are arranged in opposite pairs. The flowers are white to dark pink with a darker red centre, with a basal tube 2.5–3 cm long and a corolla 2–5 cm diameter with five petal-like lobes. The fruit is a pair of follicles 2–4 cm long and 3 mm broad.

In the wild, it is an endangered plant; the main cause of decline is habitat destruction by slash and burn agriculture. It is also however widely cultivated and is naturalised in subtropical and tropical areas of the world.

Naming

''C. roseus'' is known as "Noyon Tora"in Assamese,"noyontara" in Bengali, ''sadaphuli'' in Marathi, ''boa-noite'' and ''maria-sem-vergonha'' in Portuguese , ''vinca-de-madagáscar'', ''vinca-de-gato'' , vinca-branca , vinca or ''boa-noite'' in Portuguese , ''vinca del Cabo'', ''vinca rosa'' or ''vinca rosada'' in Spanish, ''putica'' in Venezuela and ''nityhakalyani'' in Tamil .

Uses

The species has long been cultivated for herbal medicine and as an ornamental plant. In Ayurveda the extracts of its roots and shoots, though poisonous, is used against several diseases.
In traditional Chinese medicine, extracts from it have been used against numerous diseases, including diabetes, malaria, and Hodgkin's lymphoma. The substances vinblastine and vincristine extracted from the plant are used in the treatment of leukemia and Hodgkin's lymphoma.

This conflict between historical indigenous use, and recent patents on ''C.roseus''-derived drugs by western pharmaceutical companies, without compensation, has led to accusations of biopiracy.

It can be dangerous if consumed orally. It can be extremely toxic, and is cited in Louisiana State Act 159.

As an ornamental plant, it is appreciated for its hardiness in dry and nutritionally deficient conditions, popular in subtropical gardens where temperatures never fall below 5 °C to 7 °C, and as a warm-season bedding plant in temperate gardens. It is noted for its long flowering period, throughout the year in tropical conditions, and from spring to late autumn, in warm temperate climates. Full sun and well-drained soil are preferred. Numerous cultivars have been selected, for variation in flower colour , and also for tolerance of cooler growing conditions in temperate regions. Notable cultivars include 'Albus' , 'Grape Cooler' , the Ocellatus Group , and 'Peppermint Cooler' .

''C. roseus'' is used in plant pathology as an experimental host for phytoplasmas. This is because it is easy to infect with a large majority of phytoplasmas, and also often has very distinctive symptoms such as phyllody and significantly reduced leaf size.