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| Pinnately Compound Leaf and Palmately Compound Leaf |
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| A pinnately compound leaf is one in which the midrib (rachis) bears laterally a number of leaflets. The arrangement of leaflets is either alternate or opposite. Following types can be recognized. |
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| When the rachis of the pinnately compound leaf directly bears the leaflets, it is said to be unipinnate. |
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| When the leaflets of an unipinnate compound leaf are odd in number (e.g. Rose), it is said to be imparipinnate. |
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| Here, the leaves have a long main rachis (primary rachis) on which arise a number of secondary rachii in a pinnate manner. The leaflets are arranged pinnately on these secondary rachii, so that the leaf becomes doubly pinnate. Hence, it is said to be bipinnate. e.g. Delonix, Acacia, Mimosa, etc. |
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| In some plants like Moringa, the leaves have a long main rachis (primary rachis) on which arise a number of secondary rachii. The secondary rachii produce the tertiary rachii, each tertiary rachis produces the leaflets. Such leaves are said to be tripinnate. |
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| fig. 27.36 Tripinnate Compound and Decompound Leaves |
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| When the primary rachis of a compound leaf bears not only secondary but also tertiary rachii and rachii of the fourth order, the leaf is said to be decompound. e.g. Coriander. |
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