Periwinkle

Evergreen trailing vine, spreading along the ground and rooting along the stems to form dense masses of groundcover individually 2-5 m across and scrambling up to 50-70 cm high.
The leaves are opposite, nearly orbicular at the base of the stems and lanceolate at the apex, 3-9 cm long and 2-6 cm broad, glossy dark green with a leathery texture and an entire but distinctly ciliate margin, and a hairy petiole 1-2 cm long.
The flowers are hermaphrodite, axillary and solitary, violet-purple, 3-5 cm diameter, with a five-lobed corolla. The calyx surrounding the base of the flower is 10–17 millimetres (0.39–0.67 in) long with hairy margins. The flowering period extends from early spring to autumn.