The apoplastic pathway or also known as the non-living pathway provides a direction to the vascular stele through the free spaces and cell walls of the epidermis and cortex. Furthermore, the apoplastic pathway allows direct access to the xylem and phloem along the secondary root margins. Secondary roots formed from the pericycle, a cell layer just inside the endodermis. The endoderm is characterized by the Casparian stripe, a band of cell wall material deposited in the radial and transverse walls of the endoderm to move into the symplast to enter the vasculature. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get Original Essay Since secondary roots grow through the endodermis, there is a direct route to the xylem and phloem that bypasses the Casparian strip and allows herbicides to enter the vascular system without moving into the symplast or also called non-living routes . This is one of the two main pathways for water transport in plants, the other being the symplastic pathway. In apoplastic transport, water and minerals flow upward through the apoplast to the xylem of the root.[7] The concentration of solutes transported to surface organs is established through a combination of import from the xylem, uptake by the cells, and export by the phloem. The transport rate is greater in the apoplast than in the symplast. This transport method also accounts for a greater proportion of water transport in plant tissues than symplastic transport. The apoplastic pathway is also involved in passive exclusion. Some of the ions that enter through the roots do not reach the xylem. Ions are excluded from the plasma membranes of endodermal cells. Soil water and solutes could move through the cell walls of the cortical cells to the endodermis, where they would cross the plasma membrane of the endodermal cells. Water would pass through aquaporins and solutes through ion channels or transporters. This is possible in roots without suberized hypodermis and when the endodermis is in the primary stage of development. The entry of anions into the deep layers of the cortex is probably limited by charge repulsion by dissociated negative carboxyl groups in the cell walls. In general, cations cross cell walls more easily than anions, particularly if many of the carboxyl groups in the cell walls are not occupied by Ca2+ ions. However, apoplastic flow of water through roots can support large ion fluxes during periods of high transpiration. It is likely that most of the soil water absorbed by the plant moves into the apoplast through the cortex, but that solutes are absorbed by the epidermis. or outer cortical cells and then move into the symplasma across the cortex. Please note: this is just a sample. Get a custom paper from our expert writers now. Get a Custom Essay When the endoderm is suberized, water and solutes cannot enter from the apoplast and instead are absorbed into adjacent cortical cells and move through the plasmodesmata into the endoderm.