Prosopis spicigera is a small tree, ranging in height from 3–5 m. Leaves are bipinnate, with seven to fourteen leaflets on each of one to three pinnae. Branches are thorned along the internodes. Flowers are small and creamy-yellow and followed by seeds in pods. The tree is found in extremely arid conditions, with rainfall as low as 15 cm annually; but is indicative of the presence of a deep water table.
Prosopis spicigera has demonstrated a tolerance of highly alkaline and saline environments. The tree is not to be confused with the similar-looking Chinese lantern tree, Dichrostachys cinerea, which can be told apart by its flowers. While the Chinese lantern tree has bicoloured pink-yellow flowers, the true Shami tree only has yellow-coloured bristled flowers like most other mesquites.