Two routes from root hair to xylem.

Water travels from root hair to xylem through cell walls (apoplast) or cytoplasm (symplast); suberin bands in endodermal walls force the wall route into the cytoplasm.

With strips on, get water into the xylem using only the apoplast route and see where every dot is forced into a cell.

Casparian strips sit in the pericycle.

• The dicot root studied is sunflower. From outside in: epiblema, cortex, endodermis, pericycle, then the vascular strands and a small pith.
• Epiblema is the outer layer; many of its cells grow out as single-celled root hairs.
• Cortex: several layers of thin-walled parenchyma with spaces between the cells.
• Endodermis: the innermost cortex layer, one row of barrel-shaped cells with no intercellular spaces. Their radial and tangential walls carry casparian strips of suberin, a waxy material that water cannot pass through.
• Pericycle: a few layers of thick-walled parenchyma just inside the endodermis. Lateral roots start here, and so does the vascular cambium when secondary growth begins.
• Dicot root: usually two to four xylem patches and as many phloem patches, with parenchyma between them called conjunctive tissue. Pith is small or inconspicuous. A cambium ring forms between xylem and phloem later.
• Stele = everything inside the endodermis: pericycle, vascular bundles and pith.
• Monocot root: the same layers, but usually more than six xylem bundles (polyarch), a large, well-developed pith, and no secondary growth.
• In both roots the protoxylem is drawn towards the outside, next to the pericycle, and the metaxylem towards the centre.

Teaching this idea? Put the simulation on your own page or LMS with this code.