Definition of Inflorescence

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INFLORESCENCE

After passing juvenile period, angiospermic plants bear flowers. Flowers are borne singly or in cluster. A flower is said to be solitary, when occurring singly. The solitary flower may be terminal (e.g., Papaver) or axillary (e.g., Petunia).Flowers borne in clusters, together with the stem and bracts associated with them form inflorescences. Thus the mode of arrangement of flowers on the stem and its branches is called inflorescence or anthotaxy (Gk. Anthos: flower; taxis: arrangement).The axis of an inflorescence is called peduncle. When the peduncle gets flattened to form a cup like structure, it is called receptacle. The flowering shoot that comes out of acaulescent (plants having no stems or extremely reduced stems) annual plants with radical leaves (e.g., radish, tube rose, etc.) is called a scape.The flower is attached to the axis by a stalk called pedicel. A flower with pedicel is called pedicellate and a flower without it is called sessile. Behind flower, at its base there may be a small leafy structure known as bract. A flower with bract is called bracteate and a flower without bract is called ebracteate. If in between flower and bract there is again a leafy structure, then it is called bracteole. A flower with bracteole is called bracteolate and a flower without it is called ebracteolate.The aggregation of flowers in an inflorescence makes them more conspicuous to attract insects for pollination. Many flowers get pollinated by a single visit of an insect. Therefore, inflorescences combine economy with greater chances of pollination and surity of abundant seed production.

TYPES OF INFLORESCENCE

On the basis of order of development of flower within the cluster, inflorescences are classified into following types:

Racemose (indefinite type), Cymose (definite type), Special type and Mixed type.

RACEMOSE INFLORESCENCE

In this type, the growth of the main axis is indefinite, as the terminal bud does not flower. The flowers arise laterally in an acropetal succession, i.e., the oldest flower is the lowest and the youngest one is the uppermost. The order of opening of flowers (ANTHESIS) is centripetal. Racemose inflorescence may be grouped as follows :

RACEMOSE WITH ELONGATED AXIS

Having Pedicellate flowers

Raceme: It is a typical type of inflorescence. In a raceme, lateral and pedicellate flowers are borne acropetally on an elongated axis, e.g., larkspur (Delphinium ajacis), radish (Raphanus sativus), sunn hemp (Crotalaria juncea), etc.Compound raceme or panicle: Here, the axis of the raceme gets branched and the branches bear flowers, e.g., gold mohur (Delonix regia), litchi (Litchi sinensis), Yucca filamentosa, etc.

 

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