INFLORESCENCE

INFLORESCENCE

A flowering shoot or an axis bearing a cluster of flowers is called an inflorescence. The main axis of inflorescence is called peduncle. When the flowers occur singly they are called solitary. Solitary flowers may be born at apex (solitary terminal) or at axils of leaves (solitary axillary).

Types of inflorescence;- There are three types of inflorescence; racemose Inflorescence, cymose Inflorescence, and special Inflorescence

A)-Racemose Inflorescence;

When the flowers are born laterally or in axils it is called racemose inflorescence. The arrangement of flowers can be either acropetal or centripetal. Here the flowers are not born at apex of a branch or main stem. Racemose Inflorescence can be simple or compound.

a)-Simple racemose Inflorescence; in simple racemose the peduncle remains unbranched. It is further of following types

(i)-Spike;- when the stalk less sessile flowers are born on a common axis in acropetal succession it is called spike (amaranthus)

(ii)-Catkin or ament;- a hanging or pendulous spike Inflorescence consisting of small unisexual flowers is called catkin inflorescence (salix, morus alba)

(iii)-Spadix;-  a spike Inflorescence covered by thick and large brackets (leaves), (maize, banana).

(iv)-Corymb;- here the lower peduncles are long and upper are short in such a way so that all the flowers come to same level (candytuff)

(v)-Umbel;- here the peduncles are of same length and arise from same point- (centella asiatica).

(vi)-Capitulum;- here the peduncle is flat and is called receptacle which bears small flowers called florets in centripetal manner (sunflower).

b)-Compound racemose Inflorescence;- it is a kind of racemose Inflorescence in which the peduncle is unbranched. it is further of following types

(i)-Compound Panicle;- here the axis is branched and flowers are born in acropetal succession (gold mohur, yucca)

(ii)-Compound spike;- here the axis is branched and lateral branches bear sessile flowers in acropetal succession (grasses like wheat).

(iii)-Compound spadix;- it is like simple spadix except that the axis is branched here (coconut).

(iv)-Compound corymb;-. It is simple corymb type but axis is branched. Each branch has its own corymb.

(v)-Compound umbel; here also the axis is branched in a simple umbel (coriander, carrot).  

B)-CYMOSE INFLORESCENCE

In this type of Inflorescence the peduncle or main axis terminates into a flower and further growth takes place by lateral branches each below the terminal flower. It is further of three types;-

a)-Uniparous or monochasial cyme;- here a single branch arises below each flower. If the branching occurs alternatively it is called scorpoid and if it occurs on the same side of axis it is called helicoid.

b)-Biparous or dichasial;- here a pair of branches arise below a terminal flower  (jasmine)

c)-Multiparous or polychasial;- in this type more than two branches arise below each terminating flower (calotropis).

C)-SPECIAL TYPES OF INFLORESCENCE;

1)-Hypanthodium; it is a special type of inflorescence formed by the condensation of main axis into a cup or flask shaped receptacle enclosing flowers in cymose groups. The opening of this cavity is called ostiole. It is found in ficus carica (fig), ficus religiosa (peepal) and in ficus bengalensis.

2)-Cyathium; it is a special type of inflorescence formed by the condensation of peduncle into a small conical receptacle surrounded by a Cyathium involucres. The involucres contain long female and short male flowers. It is found in euphorbia pulcherrima.

3)-Verticillaster- it is a special type of inflorescence formed by the condensation of two cymose inflorescences into a head in the axils of two opposite leaves at the node. The flowers are sessile zygomorphic, bilabiate forming a cluster or verticel round the stem. It is found in lamiaceae family-ocimum sanctum, salvia.