Catharanthus roseus is commonly known as Madagascar Periwinkle or Rosy Periwinkle. This species is known as Kemunting Cina in Malay. It is actually native to Madagascar, but has over time been widely cultivated and naturalized in most tropical countries where it sometimes becomes an unwanted weed.

This species belongs to the Apocynaceae family with the characteristic presence of white latex in its bark. It is classified as a semi-shrub and can grow up to about 100 cm tall. It has shining dark green leaves arranged in opposite pairs (Ng, 2006). The leaves are oval to oblong, 2.5 – 9.0 cm long and 1.0 – 3.5 cm broad, with a light green midrib and a short petiole about 1.0 – 1.8 cm long. The flower has 5 petals with a basal tube about 2.5 – 3 cm long. The fruit is a pair of follicles, 2 – 4 cm long and 3 mm broad.

In Malaysia, C. roseus is often cultivated as an ornamental plant in the home garden and in some public areas due to its ability to tolerate extreme conditions of drought and heavy rainfall and also because it flowers continuously throughout the year. The various beautiful colours of its flowers, such as pink, purple and white, has also made it a popular choice as an ornamental plant.

Several studies conducted on the extracts of this shrub show that it contains vincristine and other alkaloids (Wong, 2001). These chemical substances have a retardant effect which can prevent the progress of leukaemia and other cancers by disrupting the mitosis process in human cells.

However, C. roseus also has a drawback as it is poisonous. All parts of this plant are poisonous and if smoked or ingested in large quantities over a prolonged period of time, an accumulation of toxins can occur in the organs such as kidneys and liver (David, 1997). The toxins in the plant are also a defense mechanism against grazing animals as they are poisonous to cattle and other livestock.