Inflorescence

Inflorescence
Definition
The arrangement of flowers on a branch in the floral region or a group of flowers on the main axis is known as Inflorescence.
Types of Inflorescence
There are various types of Inflorescence but two major types are
1. Racemose
2. Cymose
1. Racemose
The type of inflorescence in which main axis called Peduncle continues to grow and its growth is indefinite is called Racemose.
Main Characteristics

• Flowers are produced in acropetal succession.
• No flower grow on the tip of peduncle.
• The opening of flower is centripetal.

Kinds of Racemose Inflorescence
Racemose is classified into three kinds on the basis of length of peduncle which are as follows
i. Peduncle Elongated
ii. Peduncle Shortened
iii. Peduncle Flattened
i. Peduncle Elongated
In this type of racemose inflorescence, penduncle is elongated. It includes following four types
a. Raceme
b. Spike
c. Catkin
d. Spadix
a. Raceme

• Flowers and pedicellate
• Flowers and bisexual

Example
Goldmohr
b. Spike

• Flowers are sessile or non-pedicellate
• Flowers are bisexual

Example
Amaranthus
c. Catkin

• Flowers are sessile
• Flowers are unisexual

Example
Mulberry
d. Spadix

• Flowers are sessile
• Flowers are unisexual
• Flowers are covered over by one or many large bracts called Spathe

Example
Banana
ii. Peduncle Shortened
In this type of racemose inflorescence penduncle is shortened. This includes following two groups
a. Corymb
b. Umbel
a. Corymb

• Flowers are pedicellate
• Flowers have pedicels of unequal length, lower having large pedicels and upper ones having small pedicel.

Example
Iberis
b. Umbel

• Flowers are pedicellate
• Length of pedicel is almost equal and they arise from a common point.

Examples
Onion, Corriander
iii. Peduncle Flattened
In this type of racemose inflorescence penduncle is flattened. This include following two groups.
a. Head (Capitulum)
b. Spikelet
a. Head (Capitulum)

• Main axis form a disc
• Flowers are very small (florets) which are sessile
• The florets are commonly of two kinds
• Ray Florets
• Disc Florets

b. Spikelet

• It is a kind of racemose, inflorescence
• There are three bracts at its base called “glumes”
• The lower two without flowers are called “empty glumes”
• The third glume has flower in its axil called “Lemma”
• Opposite to lemma are small bracteole called plea flower

Example
Family Poaceae
2. Cymose
The type of inflorescence in which main axis called Peduncle, not continue to grow and its growth is stopped by terminal flower is called Cymose.
Main Characteristics

• Flowers are produced in basipetal succession
• Flower grow on the tip of penduncle
• The opening of flower is centrifugal

Kinds of Racemose Inflorescence
Cymose inflorescence is classified into two kinds
i. Uniparous Cyme
ii. Biparous Cyme
i. Uniparous Cyme

• The main axis soon ends in a flower
• Only one lateral branch arises from the main axis, ending in flower and so on the process continues

Types of Uniparous Cyme
There are two types of uniparous cyme
a. Scorpoid Cyme
b. Helicoid Cyme
a. Scorpoid Cyme
In this type of cymose inflorescence, branches are produced on the alternate sides.
Examples
Cotton, Forget-me-not etc
b. Helicoid Cyme
In which type of cymose inflorescence the branches arise on one side only.
Example
Sundew
ii. Biparous Cyme

• The main axis ends in terminal flower.
• At the same time, two lateral branches arise from it.
• These two lateral branches repeat the same procedure.

Examples
Pink Jasmine, Teak-Night Jasmine.
Sexual Reproduction in Flowering Plants
Flower
Flower is the reproductive part of plant, which is actually the modified form of shoot.
Explanation
Flower develops from compressed shoots with four whorls of modified leaves separated by very short internodes. These floral leaves are called sepals, petals, stamens and carpels.
Microsporophylls
The stamens are also called microsporophylls. Each microsphylls contains following three parts.
Megasporophylls
Megasporophylls are also called carpels. The carpel is flask shaped body having stigma (head), style (neck) and ovary (basal swollen part). Inside the ovary, ovules (mega sporangia) are found and each ovules has an embryo sac (megaspore) in which a female gamete is present.