A tap root is the main, central root of a plant that grows straight down into the ground. It helps anchor the plant and absorbs water and nutrients for its growth. Full definition
My generation is mobile and enjoys almost limitless choices, but is largely lacking in tap roots and all that comes with them. (nwei.org)
Due to these tumours needing a large amount of blood to survive and grow, it is not uncommon to find them with a large tap root extending into a major artery or vein. (second-opinion-doc.com)
Doak believes it spends much of its early energy building an extremely long tap root that helps ensure water and nutrients later on, but slows the plant's above - ground growth in the meantime. (discovermagazine.com)