periwinkle flower

Many years ago, my mum gave me a plant which flowers everyday.
Now, there are hundreds of Periwinkle flower plants in my house. Hundreds of years ago, Chinese settlers from china came to sarawak by ship and brought with then the seed of Periwinkle. Scientist found that it is originally from Southeastern Africa.
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Periwinkle Flowers

Periwinkle
Summary:
Foliage: Evergreen broadleafHeight: 6 inchesShape: SpreadingEvergreen foliage is glossy, dark green. Flowers are single and vary from purple
to blue to white, depending on the variety.
Plant Needs:
Zone: 4 to 9Light: Partial shadeMoisture: MoistSoil Type: Sandy, loam, or claypH Range: 3.7 to 7.0
Functions:
Suggested uses for this plant include ground cover.
Planting Notes:
Transplants readily. Rooted cuttings or established plants are normally spaced 12
inches apart.Planting in the spring is recommended for areas with severe winters.Flowers best in sunny locations, but locations with partial shade will prevent
winter damage.
Care:
Weeding and/or mulching required on regular basis until ground cover fills in
planted area.
Problems:
Susceptible to canker and dieback, although this does not frequently occur. Canker
and dieback will turn shoots dark brown, causing the plant to wilt and eventually
die back to soil level.Leaf spot also occasionally occurs.
Alternatives:
Consult local sources, including historic or public gardens and arboreta,
regarding cultivars and related species that grow well in your area.Cultivars of VINCA MINOR:`Alba' has white flowers.`Atropurpurea' has purple flowers.`Bowles Variety' has light blue flowers and clumpy growth.`Variegata' has blue flowers and leaves variegated with rich yellow.
Related species:
VINCA MAJOR does well in central and southeastern Virginia. It has larger leaves
and may flower more frequently.
Comments:
An excellent evergreen ground cover which blooms in April and sometimes again in
the fall.Stems root readily making this a fast spreader.Commonly used for planting under trees and shrubs, on slopes, on the north side of
buildings, near steps, and as a hanging plant.