EXPERIMENT 8 Objective. To identify and comment upon different types of inflorescence.

                                               EXPERIMENT 8

Objective. To identify and comment upon different types of inflorescence.

INTRODUCTION

1.The arrangement and distribution of flowers over a plant is called inflorescence or inflorescence is the name of modified shoot that is specialized to bear flowers.

2.Inflorescence is of five types-Solitary, racemose, cymose, mixed and special.

3. Solitary flowers occur singly or are separated from other flowers of the same plant by vegetative regions., Petunia, Shoe flower, Poppy.

4.Racemose inflorescence is an indeterminate inflorescence which shows indefinite growth and bears either acropetal (older towards base and younger towards apex) or centripetal (older towards periphery and younger towards center).

5. Cymose inflorescence is the name of determinate or definite inflorescence in which the tip of the main axis terminate in a flower and further growth continues by one or more lateral branches which also behave like the main axis. The arrangement of flowers is either basipetal or centrifugal.

6. In mixed inflorescence two or more types of inflorescence get mixed up.

7.Special inflorescences are highly modified and densely crowded.

8. The presence of flowers in the form of inflorescence, make them more prominent to the pollinators (pollinating agents) and a single visit of the latter can pollinate a large number of flowers.

REQUIREMENTS----Fresh specimens of different types of inflorescence, practical record book, pencil, eraser, etc.

PROCEDURE

1.Observe the specimen carefully and note down the arrangement of flowers on the peduncle and any other feature of special interest

2.Draw the specimen on the practical note book.

3Write down the features of the inflorescence.

IDENTIFICATION AND COMMENTS

RACEMOSE INFLORESCENCE

1. TYPICAL RACEME OF LARKSPUR (Delphinium)/MUSTARD (Brassica)

Comments

(i) The peduncle is unbranched and elongated.

(i) The flowers are stalked or pedicillate arising in an acropetal manner i.e., older flowers at the base and younger towards the tip.

2. CORYMB OF CANDYTUFT (Iberis amara)

Comments

(i) The peduncle is unbranched and bears pedicillate flowers in an acropetal manner.

(i) The pedicels of the lower flowers are longer, thus, all the flowers come to lie at the same level.

3. SPIKE OF ACHYRANTHUS/BOTTLE BRUSH (Callistemon)

Comments

(i) The peduncle is elongated.

(it) The flowers are sessile and arise in acropetal fashion.(

4. CATKIN OF MULBERRY (Morus)

Comments

(i) The inflorescence is compact with a short peduncle and often hanging.

(ii) The flowers are unisexual and sessile arising in an

3.On maturity the spike falls down as a single unit.

5. SPADIX OF BANANA/COLOCASIA (Kachalu)

Comments

(i) It is a special type of spike which possesses a fleshy peduncle.

(ii) The peduncle bears sessile unisexual flowers (in Colocasia) or bisexual flowers (in Banana).

(iii) The entire inflorescence is covered by one or more green or coloured bract called spathe.

6. UMBEL OF CARROT/CORIANDER/CENTELLA (Brahmi)

Comments

1.The peduncle is reduced.

(2) The peduncle bears a cluster of flowers with stalks of equal length which arise from a single point.

3.The flowers arise in centripetal manner.

(iv) An involure or a whorl of bracts is often present at the base of flowers. Umbel is generally branched, such an umbel is called as compound umbel.

7. HEAD OR CAPITULUM OF SUNFLOWER (Helianthus)/MARIGOLD

Comments

(i) The main axis is flattened into a more or less convex structure called receptacle.

(ii) The receptacle bears sessile flowers (called florets) in a centripetal manner.

(iii) The inflorescence is surrounded by prominant bracts.

CYMOSE INFLORESCENCE

1. MONOCHASIAL (Uniparous) CYME OF BEGONIA/COTTON

Comments

(i) The main axis terminates in a flower.

(ii) A single lateral branch pushes it to one side but also itself ends in a flower.

(iii) This pattern is repeated and the peduncle is formed by the fusion of axillary branches and the main axis. Such an axis is called sympodial.

2. DICHASIAL (Biparous) CYME OF PINK (Dianthus)/SILENE/JASMINE

Comments

(i) The main axis terminates in a flower.

(ii) Two lateral branches develop on either side of the terminal flower of the main axis.

(iii)The lateral branches also end in a flower and may again branch similarly.

3.polychasial multiparous Cymose of calotropis hemalia patens 

comments 

1. The main axis terminate in a flower .

2. More then two lateral branches arise from the base of the terminal flowers.

4.CYMOSE HEAD OF ACACIA ANTHOCEPHALUS ALBIZIA 

COMMENTS

1. The main axis is reduced into a globular receptacle,

2. Sessile or sub sessile flower are borne centrifugally around the receptacle.

SPECIAL INFLORESCENCE

1. HYPANTHODIUM OF FIG (Ficus casica)/PIPAL (Ficus religiosa)/BANYAN (Ficus bengalensis)

Comments

a) The main axis forms a cup shaped receptacle with a small opening at the top.

(ii) Small sessile unisexual flowers are enclosed within the cup in cymose groups.

(i) The male flowers lie towards the pore and female flowers towards the base.

2. VERTICILLASTER OF OCIMUM (Tulsi)/SALVIA

Comments

(i) Two clusters each having 3-5 flowers develop on a node in the axils of opposite leaves.

(ii) Each cluster consists of a dichasial cyme with monochasial branches in an alternating manner.

(iii) The flowers are sessile.

(iv) The opposite clusters often give rise to the appearance of a whorl or verticil due to over crowding.

3. CYATHIUM OF POINSETTIA/EUPHORBIA

Comments

(i) In this inflorescence the involucre forms a cup.

(ii) Single female flower (without perianth) arise in the centre which is surrounded by a large number of male flowers represented by stalked stamens.