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| Stipules |
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| At the base of the petiole, in many plants, a pair of lateral appendages known as stipules are present. Leaves with stipules are called stipulate (e.g., Hibiscus) and the leaves without stipules are called exstipulate (e.g., Mango and all monocots). |
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| Stipules exhibit the following conditions. |
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| If a leaf has two free stipules, one on either side of the leaf base, they are termed free lateral stipules. (e.g., Hibiscus) |
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| These attach themselves to the petiole for a short distance by their inner margins (e.g., Rose). |
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| If the two stipules of a leaf fuse by their inner margins in such a way that this fusion product is axillary in position, they are described as intra petiolar stipules (e.g., Saraca indica). |
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| When the stipules form a hollow tube encircling the stem from the node up to a certain height of the internode, it is said to be ochreate. (e.g., Polygonum). |
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| These are large leaf-like stipules which synthesize food material (e.g., Pisum, Lathyrus). |
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| fig. 27.33 Types of Stipules |
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| Inter-Petiolar Stipules |
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| In some plants with opposite stipulate leaves, a fusion of the two stipules present on the same side but belonging to the different leaves, is seen at the node. These two fusion products or pairs of stipules would be present between the petioles of the two opposite leaves. Hence, they are termed inter petiolar stipules (e.g., Ixora, Moringa). |
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| If the stipules of a leaf fuse by their outer margins in a position opposite to the leaf attachment, the fusion product is described as an opposite stipule (e.g., Ficus elastica). |
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| Here the stipules are modified into tendrils which help plants in climbing (e.g., Smilax). |
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| Stipules are sometimes modified into hard and pointed structures called spines. Such stipules prevent the plants from being eaten by animals (e.g., Zizyphus). |
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