Problem 59 - Objective Biology for NEET

Question

Based on the position of calyx, the corolla and androecium in respect of the ovary on thalamus, the flower is of how many types (a) 1 (b) 2 (c) 3 (d) 4

Step-by-Step Solution

Answer

The flower is of 3 types.

Step 1: Understand the Classifications

Let's recall the classifications of flowers. Flowers are usually classified based on the positions of calyx, corolla, androecium, and ovary on the thalamus into the following types: Hypogynous, Perigynous, and Epigynous.

Step 2: Count the Types

We count the number of different classifications mentioned earlier, which are: Hypogynous, Perigynous, and Epigynous.

Step 3: Choose the Correct Answer

Since there are three types of flower classification based on the position of calyx, corolla and androecium with respect to the ovary on the thalamus, the correct answer is (c) 3.

Key Concepts

Hypogynous Flowers

Hypogynous flowers are a type of flower classification based on the position of the floral parts in relation to the ovary. In hypogynous flowers, the ovary is situated above all other parts of the flower. This means that the calyx, corolla, and androecium, which are the other parts of the flower, are attached below the ovary. As a result, the ovary is considered to be superior in position.
Examples of plants with hypogynous flowers include the tomato and mustard. This structure is beneficial as it allows the ovary to be more protected, standing prominently at the center of the flower. Common features of hypogynous flowers:

• Ovary is free and located at the top.
• Calyx, corolla, and androecium are fused together at the base below the ovary.
• Examples include flowers from the families Solanaceae and Brassicaceae.

Understanding the structure of hypogynous flowers helps in recognizing different plant species and appreciating the diversities in flower anatomy.

Perigynous Flowers

Perigynous flowers feature a distinct structure where the floral parts are attached around the ovary at the same level, forming a cup-like shape called a hypanthium. In this case, the ovary maintains a half-inferior position.
Unlike hypogynous flowers, in perigynous ones, the ovary is neither fully superior nor inferior. This structural arrangement allows the flower to protect its reproductive parts in a unique way.

• The floral cup or hypanthium forms and surrounds the ovary.
• The calyx, corolla, and androecium are attached to the rim of the hypanthium.
• Roses and cherries are classic examples of perigynous flowers.

Understanding perigynous flowers helps in studying plant families and offers insights into their evolutionary adaptations.

Epigynous Flowers

Epigynous flowers are characterized by having their ovary located below the other floral parts. In this arrangement, the calyx, corolla, and androecium emerge from the top of the ovary, which classifies the ovary as inferior.
The flower structure in epigynous arrangements ensures maximum protection for the ovary since it is enveloped by the rest of the floral components.

• The ovary is fully covered by other flower parts.
• Floral parts (calyx, corolla, androecium) are located and grow above the ovary.
• This arrangement is seen in flowers such as daffodils and hawthorns.

Recognizing epigynous flowers is important for botanists and horticulturists who are learning about plant classification and diversity in floral structures.