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| Subaerial Stem Modifications |
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| In some plants, the sub-aerial stems are modified for the purpose of vegetative reproduction. They are of the following types : |
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| The runner arises from the base of the stem as a lateral branch and runs along the surface of the soil. It develops distinct nodes and internodes. At each node, the runner produces roots below and leaves above. In this way many runners are often produced by the mother plant and they spread out on the ground on all sides. If any accidental injury results in the separation of a runner, the severed parts are capable of leading an independent existence. E.g., Oxalis, Fragaria, Centella astatica. |
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| fig. 27.22 - Runners |
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| An offset is a short thick runner like branch which produces a new plant at its tip. The offsets grow in all directions from the main stem of the parent plant. If any accidental injury results in the separation of these units, each is capable of leading an independent existence. E.g., Pistia, Eichhornia. |
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| fig. 27.23 Offsets |
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| Here, lateral branches called stolons originate from the underground stem. The stolons grow horizontally outwards for a varying distance in the soil. Ultimately their end (terminal bud) emerges out of the ground and develops into a new plant. A runner, sucker or any basal branch which produces roots is called a stolon. E.g. Colocasia. |
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| fig. 27.24 Stolon |
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| A lateral branch arising close to the ground level, traveling underground for some distance, turning up at its end and producing a new plant is a sucker. Eg. Chrysanthemum |
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| fig. 27.25 Sucker |
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