Weed Spotter Queensland Network Newsletter Autumn 2012 edition

Osage orange (Maclura pomifera) in the Granite Belt
Osage orange is native to Texas/Arkansas areas of North
America. This deciduous tree has escaped from garden
plantings in the Granite Belt area of Queensland near
Stanthorpe and near Armidale in New South Wales. It
has formed thorny thickets principally in riparian areas,
where its seeds continue to spread by water. It generally
only attains a height of about 10 metres (Armidale area)
but specimens in Queensland have grown to 20 metres
high in the Pikedale area.
It is related to the mulberry tree (family Moraceae)
and not a citrus as the name suggests, although the
fruit does have a distinctive citrus smell. It is generally
planted for its ornamental and timber value. The leaves
and stems exude a milky sap when damaged that can
be an irritation to skin and eyes. It has light green
ovate leaves with an acuminate tip and possesses
two-centimetre-long thorns at each leaf scar along the
stems. The trees bear a round rough green fruit similar in
size to an orange. Separate male and female plants are
required for reproduction.
Craig Hunter, Biosecurity Queensland.
Osage orange infestion. Photo: Craig Hunter.
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Foliage and thorns of Osage orange. Photo: Craig Hunter.
Fruit of Osage orange. Photo: Craig Hunter.