When we look at the flowering plants around us, we notice that the flowers of these plants vary greatly in their appearance, structure, and arrangement on the branches. The mode of arrangement of flowers on the axis is termed an inflorescence. The pattern in which the flowers develop serves as the basis for the Classification of inflorescence. Some plants may have a single flower developing on the axis or a cluster of flowers developing on the same axis. Some very common inflorescences are racemes, spadix, umbel, corymb, spike, catkin, capitulum, etc.
Classification of inflorescence
Racemose and Cymose are the two forms of inflorescence.
Racemose
The main axis of this sort of inflorescence continues to grow. It does not end in bloom and instead produces blossoms in an acropetal pattern.
It comes in the following varieties:
Raceme:
When the main axis or peduncle is elongated, the flowers are pedicellate.
For example, radish
Spike:
The peduncle is elongated on this spike, but the blooms are sessile.
E.g. Achyranthes.
Spikelet:
Spikes, racemes, and panicles are little spikes arranged in a spike, raceme, or panicle pattern.
Triticum, for example, has an awned bract, three stamens, and an ovary with two feathery stigmas.
Amentum:
The peduncle of the amentum is narrow, lengthy, and feeble. The flowers are unisexual and sessile.
Mulberry, Betula, and Oak, for example. Amentum is also called Catkin
Spadix:
The peduncle of the spadix is thick, lengthy, and meaty. The blooms are unisexual, sessile, and tiny.
Colocasia, maize, aroids, palms, and other plants are examples.
Corymb:
Because the bottom flower has a considerably longer pedicel than the higher one, the peduncle is short, and all flowers are present at the same level in a corymb.
Candytuft, for example
Umbel:
An umbel is a type of inflorescence in which the flower stalks are all about the same length and grow from the same place.
A whorl of bracts forms the involucre at the base of the flower stalk.
Eg.Centella.
Capitulum:
In the capitulum, the peduncle somehow doesn’t grow. It becomes flattened, broad, and concave or convex.
Cymose
The peduncle of this type of inflorescence ends in a flower. The older flowers are grouped at the top, while the immature buds are positioned at the bottom. The basipetal succession is the name given to this arrangement.
It comes in the following varieties:
Uniparous cyme :
The peduncle terminates in the flower, producing a lateral branch at a time in a uniparous cyme.
It is divided into three categories:
(a) Bostryx or Helicoid:
Hamelia patens, Juncus, and other monochasial cymes have consecutive lateral branches that grow solely to one side of the main axis.
(b) Cincinnus or Scorpioid:
Heliotropium, for example, occurs when successive lateral branches sprout on both sides of the primary axis alternately.
(c) Rhipidium
Solanum nigrum, for example, is a flat scorpioid cyme with all the flowers at the same level.
Dichasial / biparous cyme:
In this kind, the peduncle ends in a flower, and two lateral branches emerge from the peduncle’s base.
These, too, culminate in bloom, and the lateral branches have the same layout.
Bougainvillaea, Jasmine, Teak, and Mirabilis, for example.
Multiparous cyme:
The peduncle terminates in flower, and many lateral branches emerge from the base, all of which finish in flowers.
Some other kinds of Inflorescences
Cyathium:
Euphorbia, for example, has a cup-shaped involucre with nectar-secreting glands, a single enormous female bloom in the centre that has been reduced to a pistil, and many male flowers in the form of stamens.
Verticillaster :
This form of inflorescence can be found in the Labiatae/Lamiaceae family, with the leaves oriented in opposing directions on the stalk.
Inflorescence grows from the axil of each leaf.
A lateral axial emerges from the primary axial, on which the blooms can be found.
Salvia, Ocimum, Coleus, and other plants are examples.
Hypanthium :
The peduncle has been transformed into a thin cup-like structure in this style of inflorescence.
Female flowers bloom in the bottom of the cup, while male flowers bloom closer to the mouth.
This inflorescence contains all three types of blooms.
Banyan, Peepal, and other similar plants are examples.
Inflorescence of mixed Types
A mixed inflorescence is formed when flowers are placed on the same peduncle in racemose and cymose patterns.
Mixed inflorescence comes in a variety of forms, some of which are shown below with examples:
Thyrsus:
Thyrsus is a cymose cluster that grows acropetally on an axis, such as a grape vine.
Mixed spadix:
Spadices with cymose inflorescence organised acropetally on a fleshy axis with coloured spathes, such as banana, are known as mixed spadices.
Inflorescence’s Importance
The following are the implications of inflorescence:
- The flowers are positioned so that pollen grains may be easily transferred and the plant’s reproductive success can be maximised during anthesis.
- It offers support and strength to the fruits before dissemination when they reach maturity.
- In evolutionary and systematic investigations, they play a critical role.
- Insemination is attracted to inflorescence because of its huge and beautiful form.
Conclusion
The mode of arrangement of flowers on the axis is termed an inflorescence. The inflorescence is a changed region of a flowering plant’s stalk where flowers develop. It can include changes in the length and structure of the internodes and phyllotaxis, proportions, and the decrease of main and secondary axes. Many types of inflorescence are present, Racemose and Cymose are the two main forms of inflorescence, and many importance of inflorescence is also there. It offers support and strength to the fruits before dissemination when they reach maturity.