Vinca difformis
Apocynaceae
It flowers mainly in March and April but flowers are seen
throughout the year, including January.
It is found mainly in the South and Southwest.
See the BSBI distributioin map for Intermediate Periwinkle
It grows on banks and in hedges.
It is much less common than both Lesser and
Intermediate Periwinkle is a scrambling, prostrate
evergreen perenial herb spreading for up to 2m
and with flowering stems up to 30cm.
The habit is more like Lesser Periwinkle than
The flowers are mainly white to pale mauve and,
at up to 45mm across are bigger than Lesser and
smaller than Greater Periwinkle.
The corolla tube is longer than in Lesser Periwinkle
and is white to pale blue.
The calyx lobes are a major diagnostic feature.
In Intermediate Periwinkle they are hairless and up to
18mm long. This is longer than in Lesser Periwinkle
and the absence of hairs contrasts with
The petals are wedge-shaped.
The sexual parts are inside the corolla tube.
At the base of the tube there are green, swollen
nectaries alternating with smaller carpels.
Above the nectaries there is a stylar column made
up of united styles which expand at the top to form a
flat disc-shaped stylar head. The stigmatic surface
is a band round the stylar head and there is a plume
of white hairs on top of the head.
The 5 stamens have jointed filaments and the anthers
form triangular-shaped flaps over the plume. These
flaps can just about be seen by looking down into the
corolla tube.
Leaves are dark green, leathery,lanceolate to ovate
and up to 70mm..
Previous page: Hazel
Next page: Least Periwinkle
Intermediate Periwinklein a hedgebank,
South Somerset
White Intermediate Periwinkle together with
mauve Greater Periwinkle
Intermediate Periwinkle flower
Corolla tube and sepals
Close-up of hairless sepals
View into corolla tube showing 5 anthers
Inside the corolla tube - stylar column and
side view of anthers
Opened up corolla tube - 5 stamens,
a stylar column and basal nectaries
Close-up of stylar column, disc, ring and plume
Lanceolate-ovate, leathery leaves
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