Actinomorphic Flower vs. Zygomorphic Flower

What's the Difference?

Actinomorphic flowers, also known as radial flowers, are symmetrical in shape and can be divided into equal halves in any plane. They have multiple planes of symmetry, which means that their petals are arranged in a circular or star-like pattern. On the other hand, zygomorphic flowers, also known as bilateral flowers, are asymmetrical in shape and can only be divided into equal halves in one specific plane. They have a single plane of symmetry, which means that their petals are arranged in a way that creates a distinct left and right side. This difference in symmetry affects the overall appearance and structure of the flowers, as well as their pollination strategies.


AttributeActinomorphic FlowerZygomorphic Flower
SymmetryRadial symmetryBilateral symmetry
Petal arrangementEqual-sized petals arranged in a circleUnequal-sized petals arranged asymmetrically
Petal shapeSimilar shape and sizeVaried shape and size
Pollen distributionEvenly distributedConcentrated on specific areas
Stamen positionUniformly positioned around the centerPositioned asymmetrically
Flower orientationCan face in any directionUsually faces in a specific direction

Further Detail


Flowers are fascinating structures that come in a wide variety of shapes, sizes, and colors. One way to classify flowers is based on their symmetry. Actinomorphic and zygomorphic are two terms used to describe the symmetry of flowers. Actinomorphic flowers exhibit radial symmetry, while zygomorphic flowers display bilateral symmetry. In this article, we will explore the attributes of actinomorphic and zygomorphic flowers, highlighting their differences and unique characteristics.

Actinomorphic Flowers

Actinomorphic flowers, also known as regular or radial flowers, possess a symmetrical structure that can be divided into multiple identical parts. These flowers typically have multiple planes of symmetry, allowing them to be divided into equal halves in any direction. The petals of actinomorphic flowers are usually similar in shape, size, and color, forming a perfect circle when viewed from above.

One of the key attributes of actinomorphic flowers is their ability to attract a wide range of pollinators. The symmetrical shape and arrangement of petals provide a landing platform for insects, birds, and other animals, making it easier for them to access the nectar and pollen. Examples of actinomorphic flowers include daisies, sunflowers, and roses.

Another characteristic of actinomorphic flowers is their ability to produce large quantities of nectar. The radial symmetry allows for an even distribution of nectar-producing glands, ensuring that pollinators can access the reward from any direction. This abundance of nectar serves as a powerful attractant, increasing the chances of successful pollination.

Actinomorphic flowers also tend to have a simpler floral structure compared to zygomorphic flowers. The number of floral parts, such as petals, sepals, and stamens, is often consistent and can be easily multiplied by the number of symmetry planes. This regularity in floral structure makes actinomorphic flowers visually appealing and aesthetically pleasing.

Furthermore, actinomorphic flowers are often self-compatible, meaning they can successfully self-pollinate. The symmetrical arrangement of reproductive organs, such as stamens and pistils, allows for efficient transfer of pollen within the flower. This self-compatibility can be advantageous in environments with limited pollinator availability or in species that rely on self-pollination for reproduction.

Zygomorphic Flowers

Zygomorphic flowers, also known as irregular or bilateral flowers, exhibit a distinct bilateral symmetry. This means that the flower can only be divided into two equal halves along one plane. The petals of zygomorphic flowers are often different in shape, size, or color, resulting in an asymmetrical appearance.

One of the main attributes of zygomorphic flowers is their specialization for specific pollinators. The bilateral symmetry allows for precise positioning of floral parts, directing pollinators towards the reproductive organs and nectar. This specialization increases the efficiency of pollination, as only specific pollinators capable of accessing the reward can successfully transfer pollen. Examples of zygomorphic flowers include orchids, snapdragons, and sweet peas.

Zygomorphic flowers often possess a landing platform or a specialized structure that aids in attracting and guiding pollinators. These structures can be in the form of a lower petal, known as a lip or labellum, which provides a stable platform for insects to land on. The lip may also have markings or patterns that act as visual cues, guiding the pollinators towards the nectar and reproductive organs.

Another attribute of zygomorphic flowers is their ability to produce nectar in a concentrated area. Unlike actinomorphic flowers that distribute nectar evenly, zygomorphic flowers often have nectar spurs or tubes that store nectar at the base of the flower. This concentrated nectar source ensures that only pollinators with long proboscises or specialized mouthparts can access the reward, further enhancing the flower's specialization for specific pollinators.

Furthermore, zygomorphic flowers often have complex floral structures with varying numbers of petals, sepals, and stamens. The asymmetrical arrangement of these floral parts adds to the uniqueness and visual appeal of zygomorphic flowers. The complexity of their structure also allows for intricate mechanisms that aid in pollination, such as trigger mechanisms that release pollen when a pollinator lands on a specific part of the flower.


Actinomorphic and zygomorphic flowers represent two distinct types of floral symmetry. Actinomorphic flowers exhibit radial symmetry, attracting a wide range of pollinators with their symmetrical shape and abundant nectar. They often have a simpler floral structure and are self-compatible, allowing for efficient self-pollination. On the other hand, zygomorphic flowers display bilateral symmetry, specializing in attracting specific pollinators through their asymmetrical appearance and concentrated nectar sources. They often possess specialized structures and complex floral arrangements that aid in efficient pollination. Both types of flowers have their unique attributes and play important roles in the reproductive success of plants.

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