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| Racemose Inflorescence |
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| In racemose inflorescence the main axis is capable of continuous growth and it does not end in a flower. The flowers show acropetal succession on the main axis. The older flowers are towards the base and younger flowers are towards the apex. Sometimes the main axis becomes shortened and the flowers become clustered. In such cases the flowers are said to show Centripetal succession. Here, older flowers are towards the margin and younger flowers are towards the centre. |
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| Racemose inflorescence may have elongated peduncles or shortened peduncles. |
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| fig. 27.40 Racemose Inflorescence with Elongated Peduncle |
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| Simple Raceme |
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| It has a long peduncle on which a number of pedicellate flowers are produced in acropetal succession. e.g. Crotalaria, Erythrina. |
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| Panicle |
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| It is a branched receme. Here, the peduncle produces a number of branches in acropetal succession. On these branches pedicellate flowers are again produced in acropetal succession. e.g. Mango. |
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| Spike |
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| It has a long peduncle on which a number of sessile flowers are produced in acropetal succession. e.g. Amaranthus. |
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| Catkin |
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| It is a type of spike with a pendulous peduncle. The flowers are generally unisexual. e.g. Acalypha, Mulberry. |
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| Spadix |
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| It is also a type of spike with a fleshy peduncle. The flowers are generally unisexual. The inflorescence is always accompanied by a big bract called spathe, which almost covers it. e.g. Aroids. |
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| In Coconut and Areca nut the spadix is branched and is called a compound spadix. |
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| Corymb |
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| The inflorescence axis is slightly shortened. The older flowers have the longer and the younger have the shorter pedicels. As a result of this, all the flowers of the inflorescence are found more or less at the same level. e.g. Caesalpinia. |
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| Umbel |
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| In this type of inflorescence, the main axis is shortened and bears at its tip a whorl of bracts. From the axil of each bract a flower arises. All the flowers are more-or-less at the same level. The flowers show centripetal arrangement. When the peduncle is unbranched and bears a cluster of flowers showing centripetal arrangement, the inflorescence is called a simple umbel. e.g. Hydrocotyle. |
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| When the peduncle is branched, from the tip of each branch a cluster of flowers may be produced in an umbellate manner it is called a compound umbel. e.g. Coriander, Carrot. |
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| fig. 27.41 - Racemose Inflorescence with Shortened Peduncle |
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| Head or Capitulum. This type of inflorescence is characteristic of the family Asteraceae. The peduncle is shortened and flattened into a structure called the receptacle. At the margin of the receptacle an involucre of bracts is present. From the top surface of the receptacle a large number of small, sessile flowers commonly referred to as florets are produced. The florets are of two types ray florets, arising from the margin, are zygomorphic and unisexual, and disc florets, present throughout the surface of the receptacle. They are actinomorphic and bisexual. The florets also show centripetal arrangement. e.g. Helianthus (sunflower). |
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| fig. 27.42 - Head or Capitulum of Sunflower |
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