Roots anchor the plant in the ground, and absorb and conduct moisture and nutrients to the rest of the plant. Most roots are tough, fibrous, and barely edible. The exceptions are roots that swell up with nonfibrous storage cells; they allow plants to survive temperate-zone winter to flower in their second year (carrots, parsnips, radishes) or seasonal dryness in the tropics (sweet potatoes, manioc). Root vegetables develop this storage area in different ways, and so have different anatomies. In the carrot, storage tissue forms around the central vascular core, which is less flavorful. The beet produces concentric layers of storage and vascular tissue, and in some varieties these accumulate different pigments, so their slices appear striped.