From Central and South America, Purple Wreath is one of the around 30 species.
It is a scrambling woody vine or liana that can be up to 12 m high.
Without support it grows as a shrub or small tree up to 4 m high.
The pale brown to grey bark has pale vertical slits (lenticels or pores).
Smaller branches are 4-angled and have hairs.
The simple, opposite leaves are on short petioles up to 1 cm long.
The petioles are twisted and they have simple hairs.
The oblong to elliptic blade is up to 20 cm long and 10 cm wide
The tip can be pointed, rounded or occasionally notched and the base is wedge-shaped.
There are no teeth and the margin may be wavy.
Adult leaves are dark green above and paler underneath.
The veins are prominent on the lower surface.
Both surfaces feel rough due to the short stiff hairs.
(Another common name is the Sandpaper Vine.)
The axillary or terminal inflorescences are erect or drooping spikes up to 30 cm long.
Each has up to 30 star-shaped flowers on short pedicels around 8 mm long.
There are bracts at the base of the flowers.
All the flowers on an inflorescence face in the same direction.
They flower more than once a year.
The 5 pale blue to purple or lilac sepals form a basal tube around 5 mm long.
There are 5 flaring lobes around 2 cm long and 4 mm wide.
At the base of each lobe is a hairy triangular projection that lies along the corolla tube.
The calyx tube may be smooth or have hairs externally.
It persists on the fruit with the lobes becoming dry, brown wings.
The funnel or bell-shape corolla is much smaller than the calyx.
About 1 cm long it has 5 flaring rounded lobes on a basal tube.
There are hairs on the outer surface of the tube and the lobes.
The petals are shades of purples and blues.
There is a small white area at the base of one petal lobe.
The petals fall off early.
The 4 stamens insert near the top of the corolla tube.
There are glandular hairs on the ridges that extend down the tube from the insertion.
The anthers do not extend beyond the corolla.
They open inwards via longitudinal slits.
The elongated superior ovary of 2 carpels has 2 locules.
Pale green and smooth it holds the purple style and green, 2-lobed stigma.
The fruit are drupes enclosed in the calyx tube.
The sepal lobes act as wings when the fruit falls.
The Blue Petrea only grows to around 8 m.
Its grey-green leaves, up to 15 cm long, are on a short or no stalk.
Inflorescences of blue flowers are up to 15 cm long.
Both species have white cultivars – Petrea volubis ‘Albiflora’ and Petrea arborea ‘Broadway’.