Vachellia seyal, the red acacia, known also as the shittah tree (the source of shittim wood), is a thorny, 6– to 10-m-high (20 to 30 ft) tree with a pale greenish or reddish bark. At the base of the 3–10 cm (1.2–3.9 in) feathery leaves, two straight, light grey thorns grow to 7–20 cm (2.8–7.9 in) long. The blossoms are displayed in round, bright yellow clusters about 1.5 cm (0.59 in) diameter.
In Vachellia seyal var. fistula, which is more common on heavy clay soils, some of the thorns are swollen as domatia, housing mutualistic ants such as Crematogaster.