:::::::::::::::::::::::::::::Definition:::::::::::::::::::::::::::::::
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An Old World plants with flat five petaled, typically bluish flowers and glossy leaves. Some kinds are as ornamentals and some contain alkaloids used in medicine. 
Another term for winkle. 

::::::::::::::::::::::::::::Example::::::::::::::::::::::::::::::::::
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At the base of a tree, for example, you might have better luck with wood chips or shade-loving Ornamental plants like Ivy, periwinkle, or pachysandra. 

:::::::::::::::::::::::History And Use:::::::::::::::::::::::::
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Important plant, Madagascar periwinkle is little used by African traditional healers, it is reported as a decoction antidiabetic, indication for which it was widely used in Madagascar.