Bauhinia monandra

Bauhinia monandra.

The Orchid Tree or Pink Bauhinia is naturalised in northern Queensland.
It is a weed in these areas but is occasionally seen in Brisbane gardens.

It is mostly a small tree up to 7.5 m high but can grow as a shrub.
The almost horizontal branches are around 2 m long.
The small twigs have a varying amount of hairs.

The alternate, bilobed leaves are up to 15 or 20 cm across.
The petiole is around 5 cm long and the roughly 6 mm long green stipules fall off.
The cleft between the lobes can be shallow or halfway to the base.
There is a small appendage or mucronule at the base of the cleft.
The leaf lobes can have a round or pointed tip.
The upper leaf surface is smooth and the lower has hairs mainly along the veins.

Inflorescences are in the leaf axils towards the ends of the branches.
Consisting of just a few flowers they are erect and stand above the leaves.
The flowers are on hairy stalks a few mms long.
There are hairy bracts and bracteoles.

The bases of the 5 sepals and petals are fused forming a hypanthium 2 cm long.
It is green and ribbed, covered in short hairs and tapers towards the base.
The 5 sepal lobes on the rim also have hairs on the lower or outer surface.

There are 5 widely spreading petals up to 5 cm long and 3 cm wide near the top.
The narrow clawed bases have a few hairs.
The upper, banner petal is ovate or obovate (ovate with the widest part above the centre).
It is yellow (sometimes pink) in colour with dark reddish or crimson markings.
The other 4 petals are all similar being a pale pink or sometimes cream.
The dull red or reddish-purple markings are paler and smaller than those on the banner.

There is only one fertile stamen and it curves down almost between the lower 2 petals.
There are 5 (up to 9) infertile staminodes about 3 mm long.
The bases of the stamens and staminodes have longish hairs.
The superior ovary is on a stalk or gynophore that inserts into the hypanthium.
There are hairs on the gynophore and ovary but the style is smooth.

The flattened, straight fruit pods are up to 22 cm long and 3 cm wide.
They mature from green to a mostly hairless, pale or dark brown.
The 10 to 20 flattened, ovoid, brown to black seeds are about 1 cm long.