What is the Difference Between Flower and Inflorescence

The main difference between flower inflorescence is that flower is a modified shoot, which serves as the reproductive organ of flowering plants whereas inflorescence is a group of flowers arranged on a floral axis. 

Flower and inflorescence are two structures produced by the sexual reproduction of flowering plants. Flowers produce gametes, undergo fertilization, and form seeds while inflorescence increases the chance of cross-pollination.

Key Areas Covered

1. What is a Flower
     – Definition, Structure, Importance
2. What is Inflorescence
     – Definition, Structure, Importance
3. What are the Similarities Between Flower and Inflorescence
     – Outline of Common Features
4. What is the Difference Between Flower and Inflorescence
     – Comparison of Key Differences

Key Terms

Cross-pollination, Flower, Flowering Plants, Inflorescence, Pedicel, Peduncle, Sexual reproduction

What is a Flower

The flower is the reproductive organ produced by flowering plants. It is sometimes known as a bloom or blossom. The main function of a flower is to carry on reproduction by the production of gametes and providing mechanisms for the union of gametes in a process known as fertilization. Structurally, the flower is attached to the stem by a pedicel.

Structure of a Flower

Generally, perianth and reproductive structures are the two main parts of a flower. The perianth comprises of a calyx and corolla. The calyx is the whorl of sepals, which are small and leaf-like and appear in green color. It protects the internal structures of the flower bud. Meanwhile, the corolla is the whorl of petals, which are large and colorful. They attract pollinators to the flower.

Figure 1: Flower Structure

Furthermore, the stamen and pistil are the two reproductive structures of a flower. The stamen is the male reproductive structure, comprising of anthers and filaments. Anthers contain pollen sacs, which produce pollen grains, which give rise to sperm cells. On the other hand, the pistil is the female reproductive structure of the flower, comprising of carpels, which are the units of an ovary, style, and stigma. The ovary contains ovules with egg cells inside their embryo sacs, giving rise to seeds. Moreover, the stigma captures pollen grains and the pollen tube of the germinated pollen grains runs through the style to the ovary.

Figure 2: The Flower of Melastoma candidum

Function of a Flower

Self-pollination and cross-pollination are the two possible mechanisms of pollination in flowers. Self-pollination refers to the fusion of sperm cells and egg cells that belong to the same flower. In contrast, cross-pollination refers to the fusion of sperm cells and egg cells that belong to the different flowers of the same plant or different plants of the same species. Following fertilization, the ovary develops into the fruit with embryos developed into seeds.

What is Inflorescence

The inflorescence is a cluster of flowers with flowers arranged on the floral axis. Generally, inflorescences can be classified based on many different methods based on their general characteristics including how the flowers are arranged on the peduncle, the blooming order of the flowers and how different clusters of flowers are grouped within it. Some of these stages are the state of bracts, terminal flower, phyllotaxis, metatopy, etc. Moreover, they can be classified based on their organization as simple and compound inflorescences.

Structure of Inflorescence

The peduncle is the main stalk, holding the whole inflorescence while the rachis is a branch of the peduncle. The individual stalk which bears each flower is a pedicel. In addition, a floret refers to each of the individual flowers in the inflorescence. Furthermore, infructescence is the fruiting stage of an inflorescence. However, not all flowers occur in the form of an inflorescence and those flowers occurring individually on the stem are known as solitary flowers.

Figure 3: The Inflorescence of Epilobium angustifolium

Function of Inflorescence 

Moreover, the main importance of flowers in clusters is to provide chances for cross-pollination. Thus, inflorescences make flowers more conspicuous, attracting biotic pollinating agents such as insects and birds towards it. Large inflorescences increase the chance of wind pollination as well.

Similarities Between Flower and Inflorescence

• Flower and inflorescence are two structures of sexual reproduction of flowering plants.
• Moreover, the four components of the flower and floret are the calyx, corolla, stamen, and pistil.
• Also, both structures are responsible for the production of gametes, undergoing fertilization, and the formation of seeds.

Difference Between Flower and Inflorescence

Definition

Flowers are the seed-bearing parts of a plant, consisting of reproductive organs (stamens and carpels) surrounded by a brightly colored corolla (petals) and a green calyx (sepals) while inflorescence refers to the complete flower head of a plant including stems, stalks, bracts, and flowers. Thus, this is the main difference between flower and inflorescence.

Significance

Furthermore, an important difference between flower and inflorescence is that while the flower is a modified shoot, which serves as the reproductive organ of flowering plants, the inflorescence is a cluster of flowers arranged on a floral axis.

Stalk

Moreover, the pedicel is the stalk of the flower while peduncle is the stalk of the inflorescence.

Nodes and Internodes

A flower has distinct nodes and internodes while inflorescence does not show a distinct node and internodes. Hence, this is also a difference between flower and inflorescence.

Importance

Another difference between flower and inflorescence is that flowers produce gametes, undergo fertilization, and form seeds while inflorescence increases the chances of cross-pollination.

Examples

Some examples of flowers are roses, sunflower, etc. while some examples of the inflorescence are Wisteria sinensis, Pedicularis verticillata, Rhinanthus angustifolius, Aristolochia clematitis, etc.

Conclusion

The flower is the individual reproductive organ of a flowering plant. Generally, it is a modified shoot, containing a calyx, corolla, stamen, and pistil. The main function of the flower is to produce gametes, undergo fertilization, and form seeds. On the other hand, the inflorescence is a cluster of flowers. The main stem of the inflorescence is the peduncle. A pedicel attaches each individual flower or floret into the peduncle. Moreover, inflorescence increases the chance of cross-pollination. Therefore, the main difference between flower and inflorescence is the structure and importance.

References:

1. “Flower Structure.” Countrysideinfo, Available Here.
2. “Inflorescence.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 20 Nov. 2018, Available Here.

Image Courtesy:

1. “Ranunculus glaberrimus labelled” By Ranunculus_glaberrimus_(5384213151).jpg: Matt Lavinderivative work: Peter coxhead (CC BY-SA 2.0) via Commons Wikimedia   
2. “Individual Purple Flower” By Ltz Raptor – Own work (CC BY-SA 3.0) via Commons Wikimedia   
3. “Epilobe feuilles etroites 01” (CC BY-SA 2.0 fr) via Commons Wikimedia   

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