prop root Any of the modified roots that arise from the stem of certain plants and provide extra support. Such stems are usually tall and slender and the prop roots develop at successively higher levels as the stem elongates, as in the maize plant. Buttress roots, which develop at the base of the trunks of many tropical trees, are similar but tend to have a more flattened appearance. Stilt roots are stouter than prop roots. Those formed at the base of the mangrove tree provide firm anchorage in the soft mud of the swamps.

prop root See STILT ROOT.