Male and female plants are separate. The male cones are catkin-like. Ginkgo is documented as allergen-producing in China. Proceed through the gate in the sandstone wall and keep heading north, then veer to the right towards the Pavilion. In the lawn on your left you will see native she-oaks, Casuarina glauca.
Casuarinas are wind-pollinated.
They can be problems because pollen from a range of species is shed for much of the year, from July to April. Opposite the She-oaks are two fine specimens of the Sydney Blue Gum, Eucalyptus saligna. It is generally best to plant smaller species such as Scribbly Gum, Eucalyptus haemastoma, or Yellow Bloodwood, Eucalyptus eximia, or Plunkett Mallee, Eucalyptus curtisii. Male catkins are produced on the upper part of the tree. There are several species of poplar, each producing male and female catkins on different trees, and most appear to cause allergic symptoms in spring, from August to October.