Root hairs. Scanning Electron Micrograph (SEM) of root hairs seen on a cress root 5 millimetres long. Root hairs form an intimate contact with the soil particles, and enormously increase the root's absorbing surface area. The Cress family (Cruciferae) includes about 2,000 species of annual and perennial herbs. They are found in many kinds of habitats and are mainly northern temperate. The family includes greatly important food crops including the turnip, cabbage, cauliflower, radish, watercress and mustard. Magnification: x300 at 8x10 inch size.