Family Malvaceae (Sterculiaceae) > Subfamily Sterculioideae.
‘Brachychiton’ refers to the hairs on the seeds.
There are 31 species with 30 native to Australia and 6 in S. E. Queensland.
They are known as Kurrajong or Bottle trees.
A few species, or their hybrids, are common in Brisbane parks, streets and gardens.
Cultivated plants do not always flower each year.
Most are evergreen or deciduous trees up to 30 m high plus a few shrubs.
The trunks of some trees are swollen from water storage.
There are stipules that may persist or fall off early.
The alternately arranged leaves are from 4 to 20 cm long.
Leaves, on petioles, can be entire or lobed.
The later are palmately (digitately) lobed – divided from a common point.
The divisions can be deep or shallow and the segments wide or narrow.
In some species the juvenile and adult leaves are different.
Within a species the leaves can be variable.
Axillary inflorescences are branched clusters of flowers.
Flowers can be on a stalk or directly attached and there are bracts.
Flowers are unisexual with male and female on the same tree.
The flowers have no petals.
The bell-shaped calyx has 5 (6) sepals with their bases fused.
The slightly fleshy sepals are petal-like and can be white, cream, pink or red.
The colour can vary within a species.
Many have nectaries or nectiferous hairs inside the base of the tube.
Lobed nectaries can be separate or joined into a ring.
Male flowers have 10 to 30 stamens on the andrgynophore that is 10 to 20 mm long.
The filaments are fused into a tube enclosing the female reproductive parts.
The short terminal parts of the filaments holding the anthers are free.
There are no staminodes.
The rudimentary ovary is hidden by the anthers.
Female flowers have 5 separate carpels on an androgynophore 3 to 5 mm long.
Each locule has 2 to many ovules.
There are 10 to 30 staminodes at the base of the carpels.
The staminodes may be petal-like.
The styles are fused.
Some or all of the ovaries may develop into a fruit.
Each black or brown woody follicle is on a stalk.
Follicles are smooth or hairy outside and the inside is lined with stellate hairs.
The follicles each have numerous seeds in 2 rows.
Each seed may be in a separate, rigid compartment lined by white hairs.
In others the seeds are surrounded by a thin, papery layer with hairs externally.
Hybrids and cultivars.
There are numerous hybrids with parents including B. rupestris, B. populneus,
B. acerifolius and B. discolor.