Notes, Exercises, Videos, Tests and Things to Remember on Root
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Root is the underground descending portion of the plants axis which is white or pale brown in color without nodes, internodes, leaves, and buds. It helps in absorption of water and minerals from the soil and provides attachments to the plants. It is positively geotropic, positively hydrotropic and negatively phototropic in nature. On germination of seed, the radical of embryo gives rise to the first root known as primary root which may or may not continues its growth. On the basis of persistence of primary root angiosperm root can be categorized into two types:
If the primary root continues to grow and give rise to a secondary and tertiary root successively than it is known as tap root system. It is always underground and is the characteristic feature of dicotyledonous. In this case, the secondary roots grow in acropetal succession. Secondary roots away from the growing tip and younger towards the growing tip.
If the primary root stops to grow and a cluster of roots arise from the base of the stem or from the parts other than radical of the embryo, then it is known as adventitious root system which may be underground or aerial in nature. It may arise from the base of the stem or from nodes and internodes of a stem, branches, and leaves.
A typical type of adventitious root is known as fibrous root which arises from the base of the stem or from the nodes of a horizontally growing stem which is always underground and is the characteristic feature of monocotyledon.
|Taproot system develops from the radicle of the embryo.||Adventitious root system develops from any part of the plant except radicle.|
|It is always underground.||It may be underground or aerial.|
|It consists of prominent root that gives many thin lateral branches.||It consists of a cluster of roots which may develop from the same point.|
|Primary root persists throughout the life of a plant.||Primary root is short-lived and is soon replaced by adventitious root.|
|It penetrates deep into the soil.||It does not penetrate deep into the soil.|
Characteristics feature of a dicotyledon.
|Fibrous root is a characteristic feature of monocotyledon, however, this root may be present in dicot.|