Stenocarpus sinusatus.
Family Proteaceae > Subfamily Grevilleoideae > Tribe Embothrieae > Subtribe Stenocarpinae.
The Stenocarpus genus has about 25 species with 9 or 10 native in Australia.
The Queensland Firewheel tree is seen in public spaces and occasionally in gardens.
It can grow up to 30 or 40 m high.
The base is flanged or buttressed and the grey or brown bark is rough.
There are tiny redddish hairs on young stems and buds.
The alternately arranged leaves are on stalks up to 2.5 cm long.
Juvenile leaves are lobed or dissected to various degrees.
Adult leaves are up to 30 cm long and 5 cm wide, and obovate to elliptic.
They are leathery, usually with a rounded tip and a characteristic wavy edge.
Young leaves have rust-coloured hairs on the petiole and lower blade surface.
Older leaves may have a few hairs on the petiole and the midvein underneath.
The upper surface is a shiny green and the lower surface is paler.
Terminal or upper axillary inflorescences are 1 to 4 umbels each with up to 20 flowers.
The peduncles (the main stalks) are up to 10 cm long and there may be bracts at the base.
The flowers in the umbel arise from the top of the peduncle in a ring like the spokes in a wheel.
Each bisexual flower is on a stalk or pedicel up to 1.5 cm long.
The bright red flowers are up to 3.5 cm long and have 4 tepals forming a long, narrow tube.
In the bud the terminal 5 mm, holding the anthers, is expanded and yellow.
The hypogynous, nectar producing glands form a partial ring at the base of the ovary.
The 4 anthers, 2.5 mm long, are inserted into the expanded, cup-like tips of the tepals.
The superior ovary, on a stalk or gynophore up to 2 cm long, is finely hairy.
The style is around 2 cm long and the stigma and presenter initially lie among the anthers.
The anthers deposit pollen on the pollen presenter, a special disc-like section around the stigma.
As the flower grows the tepals separate on the lower side, the tips bend backwards and the style escapes from the tube.
Nectar feeders get pollen on them as they brush against the pollen presenter.
The fruit are brown, curved, cylindrical or ellipsoidal follicles up to 10 cm long.
They have a narrow beak and the tightly packed seeds are in 2 rows.
The circular, flat seeds are winged.
This is the only Australian species with red flowers the others being cream, yellowish or greenish.
J.F.
