Simulation · Biology · Class 11
Two routes from root hair to xylem
From the lesson Dicot and monocot roots in Anatomy of Flowering Plants. Change the values and watch what happens.
Two routes from root hair to xylemBiology · Class 11
The idea behind it
NCERT §6.2.1, §6.2.2, Figure 6.3
- 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.