Image: primary root of a dicot plant (buttercup), stained with Alcian blue and safranin.
Epidermis: it is a layer made up of small cells with a thin cuticle and a few absorbing root hairs.
Cortex: it is the wider region of the root. The cortex is parenchyma tissue with storing function. The water can circulate through the intercellular spaces.
Endodermis: it is the layer of cells found immediatly below the cortex. It is a typical structure of primary roots. The endodermis cells show a characteristic cell wall thickenings called Casparian bands (not visible in this image). In this image, endodermis cells look to have a continuous thick cell wall, but it is actually a thicker strand of the cell wall that surrounds the complete margin of the cell.
Pericycle: it is the cell layer below the endodermis. Pericycle cells look like parenchyma cells and retain the meristematic function because lateral roots are generated from the pericycle.
Primary xylem: it is the vascular tissue, formed from the procambium meristem, that shows larger and lignified cell walls (stained in red). Among the xylem cells, smaller sclerenchyma (red cell walls) and parenchyma (blue cell walls) cells can be observed.
Primary phloem: it is the vascular tissue formed from the procambium meristem, with cells showing thin primary cell walls (stained in blue). The primary phloem cells are found in small groups between the spokes of primary phloem.