The Vanilla orchid is native to Mexico, Central America, Colombia and Brazil.
Its beans are the main soUrce of vanilla essence.
Plants have become naturalised in rainforests in north-eastern Queensland.
It is an evergreen vine mainly growing in soil or in trees as an epiphyte.
With no support stems will grow across the ground until they find some support.
Young stems zig-zag and use their fleshy aerial roots to climb.
Older stems, up to 1 cm across lack aerial roots and trail down.
Stems will branch in bright sunlight and they can grow to over 20 m in the wild.
Leaves alternate along the stem in 2 ranks (distichous).
Any aerial roots grow from the opposite side of the nodes.
The flat blades are on a petiole around 1 cm long.
The fleshy leaves are up to around 24 cm long and 8 cm wide.
They are lance-shaped, elliptic or oblong with a pointed tip.
Axillary inflorescences are a raceme around 6 cm long on a short peduncle.
The wide ovate bract at the base of the peduncles is up to 1 cm long.
Along the raceme are up to 20 tightly packed resupinate (upside down) flowers.
Flowers, opening from the raceme base first only last a day.
The 3 fleshy sepals are up to 6 or 7 cm long and 1.5 cm wide.
The yellow-green spreading sepals are narrowly ovate to oblanceolate.
The corolla, up to 5 cm across has 2 lateral petals similar to but smaller than the sepals.
These greenish-yellow petals have a keel on the outer surface (dorsal).
The roughly 3-lobed third lip or labellum can be nearly 10 cm long.
The basal edges, of up to half the lip, are fused to the column.
The lateral lobes of the middle section curl up over the column.
The wide distal lobe, with a wrinkled edge curls back (under).
Running down the centre of the lip are lines of small nodules (the callus) and some hairs.
The lip is yellow-green with a darker yellow or orange tip.
The central white slightly curved column is around 3 cm long.
At the top is the anther, with yellow pollinia, above the concave stigma.
Plants can self-pollinate but a pollinator is needed for this to happen.
The fruit are a sometimes curved, pendulous pod around 24 cm long and 1 cm wide.
They are commonly, but incorrectly called beans.
Over a period of 9 months they mature from green to black.
Each has thousands of tiny black seeds.
J.F.
