Eucalyptus cinerea aka Argyle Apple

Eucalyptus cinerea is an evergreen tree in the myrtle family. Its common names include argyle apple and silver dollar tree. It comes from southeastern New South Wales and northeastern Victoria, Australia. Its dense crown has upright and spreading branches. Growth is fast, with young plants gaining several feet each year.

Garden trees reach about 33–49 feet (10–15 metres) tall. RHS gives a spread of 13–26 feet (4–8 metres). Oregon State reports widths up to 45 feet (14 metres). Trees in their native range can reach 60 feet (18 metres). Young branches have smooth, reddish-brown to grey bark that peels. Older bark becomes rough, stringy and split by deep grooves. Round young leaves grow in opposite pairs without leaf stalks. A pale wax coat gives them a silver-blue look. These leaves can stay on the tree for many years. Adult leaves grow alternately and have stalks. They are longer, pointed, and sometimes curved like a sickle. The leaves give off a strong scent when bruised.

Small white flowers appear in late spring, though garden plants rarely flower. Each flower has many stamens, and small clusters grow beside leaves. Woody, funnel-shaped capsules follow the blooms and hold many seeds. Gardeners grow this tree chiefly for its foliage. Cut leafy stems suit fresh and dried flower displays. The tree also serves as an accent, screen or hedge. In cold areas, gardeners grow it in pots or as an annual. Potted plants need indoor shelter before the first autumn frost.

Give it full sun and soil that drains well. It grows in sand, loam or clay with good drainage. RHS recommends acid to neutral soil. Young plants need moisture; established trees can cope with drought. It also tolerates wind and some salt exposure. Sources list USDA zones 8–11 and UK hardiness H5. Cold can kill stems, though some plants regrow from the base. Pruning can help retain the round young leaves.

Serious pest and disease trouble is not usual. Possible pests include eucalyptus gall wasp and eucalyptus sucker. Silver leaf, honey fungus and oedema can also occur. Leaves, bark and sap pose poisoning risks to people and pets. Handling leaves or bark can irritate skin. Swallowing the oil can cause severe illness, including coma. Sources note herbal uses of the oil, not safe food use.