Leaves simple, alternate, to 5.5 cm by 3 cm, elliptic to obovate or almost rhomboid, entire or somewhat scalloped towards the tip; juvenile foliage linear. Blade dark green, with numerous conspicuous oil dots (and hence aromatic). Stalk to 6mm in length.
Flowers white or pinkish, about 1 cm across, fragrant; solitary in leaf axils. Appear Aug to Nov.
The dense, prickly habit makes this species a useful nesting site for small rainforest birds and as a screen plant.
Propagate from fresh seed or cuttings, which are slow to develop roots. Could also be budded onto exotic citrus rootstock.
Hardy but slow-growing, needing some protection when young. Must have excellent drainage and prefers a sheltered position. Appreciates mulching and extra watering during dry periods, and organically rich soil. Moderately frost tolerant.

Photo: Robert Whyte
Fruit, foliage
Edible acidic pulp; ripe fruits are eaten raw or can be made into marmalade and added to cold drinks for extra flavour.
Citrus is Latin for lemon (cirtron) australis means southern (hemisphere).
Six small citrus species known as lime are native to Australia. Five are found only in the rainforests of the north. The sixth, the Desert Lime (Citrus glauca), grows in semi-arid areas of southeastern Australia. Two of the five rainforest limes occur naturally in southeast Queensland – the Finger Lime (Citrus australasica) and a small round lime known as the Round Lime or Gympie Lime (Citrus australis) and called Dooja How.

Photo: Bruce Noble
Leaves and thorns

Photo: Robert Whyte
Closeup of variation in leaf shape

Photo: Robert Whyte