Eucalyptus tetraptera, square-fruited mallee,also four-winged mallee is a low, straggly mallee with smooth, grey or whitish-grey bark. Juvenile leaves are stalked, ovate to broadly elliptical, to 12 × 7 cm. Adult leaves are stalked, elliptical to lanceolate, thick, to 25 × 7 cm, concolorous and glossy green. Flowers are pink in late winter to mid summer. Fruit is red, sessile, oblong and winged along corners to 5 × 4.2 cm.