Animation of the cellular anatomy of the root of a plant, showing water uptake through the apoplast pathway, in which water travels in the cell walls. Roots serve to collect water (red blue) and dissolved nutrients from the soil (brown) and pass them to the rest of the plant. The outermost layer consists of hair cells (red), which are very fine and increase the surface area available for absorption. Water passes into the hair cell walls by osmosis, and crosses the epidermis (green) into the walls of the parenchyma (grey), a large mass of undifferentiated cells that forms the cortex of the root. The innermost layer of the cortex is the endodermis (yellow), whose cell walls contain an impermeable waxy layer called the Casparian strip (blue). This serves to prevent the apoplastic movement of water through the cell walls, forcing it to flow through the cells' cytoplasm, before it enters the next layer, the pericycle (purple). This is the outer layer of the vascular tissue, which passes water into the xylem. Xylem is the vascular tissue that carries water upwards to the rest of the plant. Although osmosis is important at bringing water into the hair cells, it is the pressure created by evaporation (transpiration) from the leaves that draws water up the plant. | |
Licence : | Droits gérés |
Crédit : | Science Photo Library / Biocosmos / Francis Leroy & Maximilien Moens |
Model Release : | Non requis |
Property release : | Non requis |
Durée : | 45 Secondes |
Aspect ratio : | 16/9 |
Restrictions : | - |