Any tree or shrub of the mimosa family that grows in warm regions. The plant called "shittah" (singular) or "shittim" (plural) in the King James Version of the Bible is certainly the acacia tree. This was the only timber tree of significant size that grew in the Arabian desert. Acacia wood was used in the building of the ark of the covenant (Exodus 25:10).
Acacia tortilis is the largest and most common tree in the desert where the Israelites wandered for 40 years. It is especially noticeable on Mount Sinai and was probably the type of wood used for making the tabernacle furnishings.
Acacia seyal is less common today. It can grow as tall as 7.6 meters (25 feet). It has yellow flowers on twisted branches. The wood is close-grained, heavy, and hard. It has an orange-brown color and was highly valued for making cabinets. The ancient Egyptians used acacia wood to seal shut their mummy coffins.