Acacia (Robinia pseudoacacia) is extremely hard and dense.  It is resistant to rot and very durable, making it ideal for furniture, flooring, boats, and more.  From naturalized forests in Europe, trees range in size from large shrubs to taller trees 70 ft. or taller with diameters of 10” to 36” or more depending on age and growing conditions.  Thorns gave this wood the nickname “Spear Tree” as the thorns will easily act as a spear to any unwitting passers by.