BIOL 2004 Lecture Notes - Lecture 10: Casparian Strip, Palisade Cell, Pericycle
Document Summary
The main functions of the roots are: anchor the plant, absorb and conduct water & minerals. Roots produce hormones & other substances absicic acid (aba), cytokinin and ethylene. There are two main patterns of root growth: taproot. Most dicots and gymnosperms have a taproot system. Taproot develop directly from the radicle and produces branch roots called lateral roots. Lateral roots then develop their own branch roots. Because of amyloplasts (colorless plastids) in roots: amyloplasts in root cap cells cells are also called statoliths, have to look at amyloplasts in transmission. Instead of one main roots, numerous roots arise from the lower part of the stem. In fibrous root system, no single root stand out as the largest. Typically shallower and more horizontal than a taproot system. Roots can extend significantly deeper in both taproot and bibrous systems. Typically, 50% to 90% of a plant"s roots occue in the top 30cm of soil.
