pink periwinkle

Catharanthus roseus
habit (Photo: Sheldon Navie)
habit of white-flowered form (Photo: Sheldon Navie)
leaves and white flower (Photo: Sheldon Navie)
close-up of pink flower (Photo: Sheldon Navie)
immature fruit borne in pairs (Photo: Sheldon Navie)
close-up of leaves and mature fruit releasing their seeds (Photo: Sheldon Navie)
seedlings (Photo: Sheldon Navie)
modern cultivar (Photo: Sheldon Navie)
modern cultivar (Photo: Sheldon Navie)
modern cultivar (Photo: Sheldon Navie)
Herb
Opposite
Simple
White
Pink
Green
Discoloured

A short-lived or long-lived herbaceous plant or sub-shrub growing up to 1 m tall. Its stems and leaves contain a milky sap and its young growth is often finely hairy. Its paired leaves (2.5-9 cm long) have glossy green upper surfaces and paler undersides. Its flowers (2.5-5 cm across) are usually pink with a darker centre, but other coloured forms are also found. Its cylindrical fruit (20-38 mm long and 3-6 mm wide) are usually borne in pairs.

Common names 
Also known as: pink periwinkle, bright-eyes, Cape periwinkle, Madagascar periwinkle, old-maid, periwinkle, rose periwinkle, rosy periwinkle,
Family 
Apocynaceae
Deciduous 
No
Flowering time 
Year round
Native/Exotic 
Exotic
Origin 
Native to Madagascar.
Notifiable 
No
Council declaration 
SIL – Special Investigation List
Known distribution 

This species is common in eastern Queensland and also naturalised in the coastal districts of northern New South Wales, in the northern and western parts of Western Australia and in the coastal districts of the Northern Territory.

Habitat 

A weed of disturbed sites, waste areas, old gardens, footpaths, parklands, roadsides, railway lines, rocky outcrops, coastal environs, urban bushland, open woodlands, forest margins, gullies, creek-beds, floodplains and riparian vegetation.

Habit 

A short-lived (i.e. biennial) or long-lived (i.e. perennial) herbaceous plant or sub-shrub with upright (i.e. erect) stems. It usually grows 20-70 cm tall, but occasionally reaches up to 1 m in height.

Impact and control methods 

"It is most commonly associated with coastal habitats (e.g. cliff faces, rocky ocean ledges and sand dunes) and other sites with sandy soils, but also grows in bushland and disturbed natural vegetation near urban areas.

Pink periwinkle (Catharanthus roseus) is also a problem species in northern Queensland (e.g. it is abundant on Magnetic Island), and is regarded as an environmental weed in New South Wales and Western Australia."

Stem and leaves 

"Its stems contain milky sap (i.e. latex) and may become slightly woody towards the base of the plant. Younger stems are green, or sometimes tinged with red or purple, and are finely hairy (i.e. puberulent).

The leaves are arranged in pairs along the stems and are borne on short stalks (i.e. petioles) 2-10 mm long. These leaves (2.5-9 cm long and 1-3.5 cm wide) are oblong, oval (i.e. elliptic) or egg-shaped in outline (i.e. obovate) with entire margins and rounded tips (i.e. obtuse or mucronate apices). They are hairless (i.e. glabrous) or sparsely hairy (i.e. puberulent) with glossy green upper surfaces and paler undersides."

Flowers and fruits 

"The flowers are borne singly, or arranged in small clusters in the upper leaf forks or at the tips of the branches (i.e. in axillary or terminal cymes). These flowers (2.5-5 cm across) are almost stalkless (i.e. sub-sessile) or borne on short stalks (i.e. pedicels) 1-4 mm long. In the typical form they are pink with a darker centre, but other coloured forms are also appearing in naturalised populations (particularly white and reddish-pink flowered cultivars that may have purple, red, pale yellow or white centres). The flowers have five small green sepals (2-6 mm long) and five petals, which are fused together at the base into a narrow tube (i.e. corolla tube) 2.5-3 cm long. These petals separate at the tip into five spreading lobes (i.e. corolla lobes) 1.2-2.5 cm long. Each flower also have five stamens and an ovary topped with a style and stigma. Flowering occurs throughout the year, but is less apparent during winter.

The cylindrical fruit resemble small pods (i.e. they are follicles) and are usually borne in pairs. These fruit (20-38 mm long and 3-6 mm wide) are green and finely hairy when young. They turn pale brown and split open when mature, releasing the numerous small seeds (1-2 mm long). These seeds are black or dark brown in colour, covered in numerous tiny bumps (i.e. they are finely tuberculate), and grooved on one side."

Reproduction and dispersal 

This species reproduces by seed. These seeds are spread by water, wind and in dumped garden waste. They may also be dispersed by animals, vehicles, and in contaminated soil."

Similar species 

Pink periwinkle (Catharanthus roseus) may sometimes be confused with impatiens (Impatiens walleriana ) and blue periwinkle (Vinca major ). However, impatiens (Impatiens walleriana ) can be easily distinguished by the spur at the base of its flowers, and blue periwinkle (Vinca major ) can be recognised by its creeping habit and bright blue or purplish flowers.