Vinca rosea 

Description: Catharanthus is a genus of flowering plants in the family Apocynaceae. Like the genus Vinca, they are known commonly as periwinkles.There are eight known species. Seven are endemic to Madagascar, though one, C. roseus, is widely naturalized around the world. The eighth species, C. pusillus, is native to India and Sri Lanka.The name Catharanthus comes from the Greek for "pure flower". These are perennial herbs with oppositely or almost oppositely arranged leaves. Flowers are usually solitary in the leaf axils. Each has a calyx with five long, narrow lobes and a corolla with a tubular throat and five lobes.

Flowering and Fruiting: Throughout the year.

Economic Importance: Catharanthus roseus, known formerly as Vinca rosea, is a main source of vinca alkaloids, now sometimes called catharanthus alkaloids. The plant produces about 130 of these compounds, including vinblastine and vincristine, two drugs used to treat cancer.

Reference: https://en.wikipedia.org/wiki/Catharanthus