Chapter 7 Inflorescence

Question 1

Define inflorescence

Answer 1

The arrangement of flowers on floral Axis or peduncle resulting in the formation of clusters or groups is called inflorescence

Question 2

Types of inflorescence

Answer 2

An inflorescence maybey
simple 
compound or 
a special types  
according to the mode of branching.

Question 3

Simple inflorescence

Answer 3

cymose racemose

Question 4

Define racemose inflorescence

Answer 4

• In this type of inflorescence the main Axis continues to grow until the last flower is formed at the apex
• acropetal succession : the younger flowers are present near the apex and older near the base
• centripetal arrangement: in some cases the main axis is compressed or flattered into a disk bearing a cluster of flowers on its upper surface. In these cases the oldest flowers are at periphery and younger ones in the centre.

Question 4

Defined racemose inflorescence

Answer 4

• In this type of inflorescence the main Axis continues to grow until the last flower is formed at the apex
• acropetal succession : the younger flowers are present near the apex and older near the base
• centripetal arrangement: in some cases the main axis is compressed or flattered into a disk bearing a cluster of flowers on its upper surface. In these cases the oldest flowers are at periphery and younger ones in the centre.

Question 5

Types of racemose influorescence

Answer 5

• simple raceme } delphinium ajacis
• Corymb } iberis Amara (candytuft)
• Corymbose raceme } in brassica
• spike } in bottle-brush
• catkin }as in mulberry
• spadix } in 🌽 maize and 🍌 banana etc
• simple umbel } in 🍒 cherry
• captitulum } 🌻 sunflower (Asteraceae)

Question 6

Simple raceme

Answer 6

The main Axis elongated
Flowers Pedicallate
The pedicels of flowers are of same size
Example in delphinium ajacis

Question 7

Corymb

Answer 7

• The main Axis elongated
• Flowers Pedicallate
• the pedicels of older flowers longer than those of younger flowers so
• all the flowers are arranged at the same level
• example in iberis Amara(candytufy)

Question 8

Corymbose raceme

Answer 8

• the inflorescence is corymbose in flowering stage
• but later becomes a simple raceme due to elongation of axis
• example in brassica

Question 9

Spike

Answer 9

The main axis elongated bearing sessile flowers

•example in bottle brush

Question 10

Catkin

Answer 10

A pendulum spike bearing unisexual flowers as in melbury

Question 11

Spadix

Answer 11

• A thick fleshy spike,
• maybe branched or unbranched,
• enclosed in one or more bracts
• example in maize banana etc

Question 12

Simple umbel

Answer 12

the growth of intenodes is suppressed after formation of first flower . The flowers are Pedicellate and arranged at same level. The older flowers are towards periphery and younger in the centre .
example in cherry.

Question 13

Ray florets

Answer 13

Ligulate, Bisexual or neuter and arranged along the periphery of the disc

Question 14

Capitulum

Answer 14

The floral Axis is reduced to a flattened disc, the receptacle;
•Florets:
clusters of small flowers the florets, is bone on the disc ,
therefore the inflorescence appears to be a single flower .
•Cup shaped Involucre:
The receptacle is surrounded by overlapping bracts that form a cup shape Involucre at the base of the receptacle .
•Homogenius captitulum:
If all the flowers in a captitulum are of same kind ,it is homogenous as in Sochus.
•Types of florets:
However in sunflower the florets are of two types
•Ray Florets
•Disc florets

Question 15

Disc florets (heterogamous)

Answer 15

Tubular, bisexual and arranged in the centre of the receptacle.This type of captitulum is called heterogamous

Question 16

Hypanthodium

Answer 16

In this case the receptacle grows upward along its margin to form a hollow pear shaped structure, with an apical opening guarded by scales. Unisexual flowers develop on the inner surface of the hollow receptacle. The male flowers are present near the apex while the female flowers occupy the rest of the surface. This type of inflorescence is characteristics of fig,banyan,peepal etc

Question 17

Cymose inflorescence

Answer 17

In this type of inflorescence the main floral axis ends in a flowers soon; and one, two or more lateral branches develop below the terminal flower. Each daughter axis ends in a flower and produces lateral branches. The flowers develop in basipetal succession that is older flower are present towards periphery and younger near the base.The Arrangement of flowers in cymose inflorescence is centrifugal i.e, the older flowers occupy the centre and the younger periphery of the clusters.

Question 18

Types of cymose inflorescence

Answer 18

Uniparous cyme
Biparous cyme
Multiparous cyme

Question 19

Uniparous cyme

Answer 19

When a single daughter axis is produced below the terminal flower.
•Scorpoid cyme:
When the successive daughter axes develop on right and left sides alternately forming a zigzag Example: Ranunculus(Ranunculaceae)
•Helicoid cyme:
Where the successive daughter axes develop on the same side,either right or left .
Example in Begonia
In both scorpoid and helicoid cyme the basal parts of the successive daughter axes become straightened up to form a false central Axis or sympodium,so that the flower come to lie opposite the bracts.

Question 20

Biparous cyme

Answer 20

In this case the main axis ends in a flower and produces two daughter axes example in Stellaria media,Ipomea etc

Question 21

Multiparous cyme

Answer 21

The main axis produces more than two daughter axes below the terminal flower example in Calotropis, Euphorbia.It looks like an umbel but can be distinguished by the opening of the middle flower first

Question 22

Compound inflorescence

Answer 22

The main axis is branched and bears flowers in the same manners as on the main axis.
TYPES:
The most common type of compound inflorescence
•Campound raceme
•Compound corymb
•Compound umbel
•Compound spike

Question 23

Compound raceme

Answer 23

It consists of several racemes borne in a racemose manner on the main axis example in delphinium ajacis

Question 24

Compound corymb

Answer 24

In this case the main axis is branched and bears a number of corymbose example in Cauliflower

Question 25

Compound umbel

Answer 25

The inflorescence comprises of a number of umbels borne in umbellate manner at the top of main axis

Question 26

Compound umbel

Answer 26

The inflorescence comprises of a number of umbels borne in umbellate manner at the top of main axis

Question 27

Compound spike

Answer 27

The main axis bears a number of sessile lateral spikes called spikelets-each comprising of one to few flowers and enclosed in specialized bracts example in avena sativa (barley) triticum(wheat 🌾)

Question 29

Special inflorescence

Answer 29

In some inflorescence it becomes difficult to make out the real mode of branching because the daughter axes may be abbreviated or suppressed or the flowers are crowded in many groups. Such inflorescence is called special inflorescence.

Question 30

Types of special inflorescence

Answer 30

Cyathium Verticillaster Scapigerous or umbellate cymose head Cymose head

Question 31

Cyathium

Answer 31

The main axis ends in a reduced female flower that is tricapillary and syncarpous pistil borne at the end of a long pedicel. •5 scorpoid cymose clusters of reduced male flowers surrounds the stalk of female flower . •Each male flower consists of a single stamen and a scaly bract at its base •The perianth leaves are completely suppressed and flowers are enclosed in a Cup shaped involucre. •Cyathium is characteristics inflorescence of euphorbia's.

Question 32

Verticillaster

Answer 32

It is a condensed cymose inflorescence .The clusters of flower are borne in the axils of opposite decussate bracts. The two clusters of flowers form whorl at the node called Verticillaster. The clusters of flower exhibit a bigamous cymose arrangement first but later becomes Uniparous cymose due to suppression of the growth of on daughter axis. The Verticillaster is found in Ocimum(niazbo),Salvia,Mint etc

Question 33

Scapigerous or umbellate cymose head

Answer 33

In onion, the flowers are borne at the end of long leafless stalk, the scape that arises in the midst of the radical leaves. The flowers are arranged in many helicoid cymose clusters. The inflorescence appears like an umbel ,there also called umbellate cymose head

Question 34

Cymose head

Answer 34

In Acacia (Kikar) and Albizzia (Shirin) the flowers are arranged in clusters forming a head. Actually each cluster is a scorpoid cyme in which the main axis and successive daughter axes have been reduced and the flowers are almost sessile.