What is the Difference Between Hypogynous and Epigynous Flower

The main difference between hypogynous and epigynous flower is that hypogynous flower has a superior ovary whereas epigynous flower has an inferior ovary. Furthermore, the hypogynous flower has sepals, petals, and stamens attached to the receptacle below the ovary while the epigynous flower has sepals, petals, and stamens attached to the top of the ovary. 

Hypogynous and epigynous flower are two types of flowers classified based on the level of the ovary. Generally, a flower is the reproductive organ of flowering plants, containing sepals, petals, pistils, and stamens. 

Key Areas Covered 

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

Key Terms 

Androperianth, Epigynous Flower, Hypogynous Flower, Level of the Ovary, Perigynous Flower

What is a Hypogynous Flower 

The hypogynous flower is a type of flower with a superior gynoecium or an ovary. However, the androperianth (collection of the androecium and the perianth) occurs below the ovary. Therefore, all the other parts of the pistil are visible to the outside. Here, the perianth is the collection of the calyx (sepals) and the corolla (petals) of the flower.

Figure 1: Ovary Position I. Hypogynous, II. Perigynous, III. Epigynous

Moreover, this androecium is attached to the receptacle also known as the thalamus below the ovary. Where, the receptacle refers to vegetative tissues near the end of reproductive stems that are situated below or encase the reproductive organs.  

What is an Epigynous Flower 

The epigynous flower is another type of flower with an inferior gynoecium or an ovary. Its androperianth occurs at the top of the ovary. Therefore, only a part of the pistil is visible in this type of flowers, including the stigma and the style. Furthermore, the receptacle of the epigynous flowers is attached to the summit of the ovary. Therefore, the parts of the androperianth develop jointly. 

Figure 2: Female Squash Flower – Epigynous

Moreover, there is a third type of flowers which contain an androperianth fused at the base to form a cup-shaped structure known as the hypanthium. However, the position of the ovary is still superior as the insertion of the hypanthium occurs below the ovary. Therefore, this type of flowers is known as perigynous flowers.  

Similarities Between Hypogynous and Epigynous Flower 

• Hypogynous and epigynous flower are two types of flowers classified based on the level of the ovary. 
• Both flowers contain sepals (calyx), petals (corolla), stamens, and pistils. 
• Also, they produce an androperianth by fusing the androecium and perianth (calyx and corolla) together. 
• Moreover, they serve as the reproductive organ of flowering plants. 
• Thus, they produce both pollen grains and egg cells, undergo pollination, fertilization, and ultimately, they produce seeds inside their fruits. 

Difference Between Hypogynous and Epigynous Flower 

Definition 

Hypogynous flower refers to the flowers having the floral parts, such as sepals, petals, and stamens, borne on the receptacle beneath the ovary while epigynous flowers refer to the flowers having the floral parts, such as the petals and stamens, attached to or near the upper part of the ovary. 

Position of the Ovary 

The main difference between hypogynous and epigynous flower is that the hypogynous flowers have a superior ovary while epigynous flowers have an inferior ovary. 

Position of the Androperianth 

Furthermore, the hypogynous flower has an androperianth attached to the receptacle below the ovary while the epigynous flower has an androperianth attached to the top of the ovary. Thus, this too is an important difference between hypogynous and epigynous flower.

Development of the Androperianth 

Moreover, another difference between hypogynous and epigynous flower is that the development of the constituents of the androperianth occurs separately in the hypogynous flower and they are well-spread while the development of the constituents of the androperianth occurs jointly from the neck of the receptacle. 

The shape of the Receptacle/Thalamus 

Besides, the hypogynous flower contains a convex or conical receptacle while the epigynous flower contains a flask-shaped receptacle. 

Fusion of the Receptacle with the Wall of the Ovary 

In addition, the receptacle of the hypogynous flower is not fused with the wall of the ovary while the receptacle of the epigynous flower is fused with the wall of the ovary. Thus, this is one other difference between hypogynous and epigynous flower.

Expansion of the Receptacle 

Also, the receptacle of the hypogynous flower has no expansions except for a central projection while the epigynous flower contains an expanded receptacle. 

Visibility of the Pistil 

Visibility of the pistil is also a difference between hypogynous and epigynous flower; a hypogynous flower has a fully visible pistil while an epigynous flower has visible stigma and style only.  

Examples 

Some examples of hypogynous flowers are persimmon, tomato, tulip, snapdragon, fleshy fruits such as true berries, drupes, etc. while some examples of epigynous flowers are the apple, daffodil, etc. 

Conclusion 

The hypogynous flower is a type of flowers with a superior ovary. Therefore, its androperianth is attached to the receptacle below the ovary. Also, it contains a conical-shaped, thin receptacle, which is not fused with the wall of the ovary. On the other hand, the epigynous flower is another type of flower with an inferior ovary. Here, the androperianth is attached to the top of the ovary. However, the expanded receptacle of the epigynous flower fuses with the wall of the ovary. Therefore, the main difference between hypogynous and epigynous flower is the position of the ovary with respect to the androperianth. 

 References:

1. “Floral Variation.” Biology 343, Available Here.

Image courtesy:

1. “Ovary position” By Ulf Mehlig – Own work (CC BY-SA 2.5) via Commons Wikimedia   
2. “Femalesquash3747” By Pollinator (CC BY-SA 3.0) via Commons Wikimedia