Vinca or Periwinkle is a prolific heat and drought tolerant annual, perfect for hot, dry areas. It's easy to grow, and requires little or no attention. A grower once reported that he has grown Vinca in the same location for 30 years. It successfully reseeded itself each year, with no effort on his part.
This plant is known by three names: Vinca, Periwinkle (or Madagascar Periwinkle), and Myrtle. Botanists will tell you that there is also a separate strain or variety of Periwinkle. Vinca plants are native to North America, Europe, China and India.
The plants are grown for its attractive glossy, green foliage, as well as its flowers. Flowers bloom all summer, and up to frost. Common colors include white, rose, pink, and red. Vinca is commonly used for borders, edging, and ground cover or bedding plants. Plants grow 1-2 feet tall.
Over the years, Vinca has been used for medicinal purposes. Applications included: Lowering blood pressure, Lowering sugar levels for diabetics, Treatment for coughs, colds, sore throats & Treating eye and lung infections.
Vinca are seldom bothered by insects and disease. Fungus problems can occur in humid or wet weather. If insect or disease problems occur, treat early with organic or chemical insect repellents and fungicide.
#source:http://www.gardenersnet.com/flower/vincaperiwinkle.htm