What is Aestivation Overview
Aestivation in plants refers to the arrangement of floral organs (petals, sepals, stamens, and pistils) in a flower bud before it opens. The term is also known as prefloration. It is often befuddled with vernation, which is the arrangement of scales and new leaves in a leaf bud before it opens. The sepals and petals are collectively known as a perianth. The course of action of perianth inside a flower bud before it blooms is known as the aestivation of plants.
What is Aestivation in plants?
Aestivation in plants means arrangement of accessory floral organs (sepals or petals) in relation to one another in a flower. Aestivation is the flower characteristic that illustrates the course of action of corolla (petals) and calyx (sepals) in connection to each other in a flower bud. Corolla and calyx are collectively known as the perianth. The term aestivation in plants is like the term vernation, which describes the organization of the leaves inside a vegetative bud.
Aestivation in plants is an important part of taxonomyas flowers of different species how different aestivation. The five different types of aestivations are:
What is aestivation: Types | What is aestivation: Examples |
Valvate Aestivation in plants | Examples of flowers with valvate aestivation include the Brassica flower and the Arabidopsis flower |
Twisted Aestivation in plants | Examples of flowers with twisted aestivation include the Hibiscus flower and the Malva flower |
Imbricate Aestivation in plants | Examples of flowers with imbricate aestivation include the Tulip flower and the Lilium flower |
Vexillary Aestivation in plants | Examples of flowers with vexillary aestivation include pea flowers, bean flowers, and lentil flowers |
Quincuncial Aestivation in plants | Examples of flowers with quincuncial aestivation include the Magnolia flower and the Liriodendron flower |
The calyx may be gamosepalous (sepals united) or polysepalous i.e., sepals free. Aestivation in plants basically refers to the way sepals and petals or the perianth, are arranged in a floral bud before it blooms. The corolla means the outer petals of a flower. The shape and color of corolla vary greatly in plants. Corolla may be tubular, bell shaped, funnel-shaped or wheel-shaped. Corolla is a combination of petals, and they are usually bright in color to attract insects for pollination.
What is Aestivation: Perianth
- The perianth is a non-reproductive (accessory, sterile) part of the flower, consisting of floral leaves surrounding the androecium and gynoecium. This is the part consisting of the calyx (sepals) and the corolla (petals). It is the non-reproductive part of the flower.
- In few plants, petals and sepals are non-differentiated and so are found as auxiliary whorls.
- For example, Polyanthus, Flowers of Crinum, etc. Flowers belonging to the Amaranthaceae family have a membranous and persistent perianth type. When a flower has both androecium and gynoecium, it is bisexual. A flower having either only stamens or only carpels is unisexual.
- The perianth or the peripheral whorl is named as polyphyllous, if the petals and sepals remain free within the case of Gloriosa superba flowers. However, if the petals and sepals are fused, the perianth is known as gamophyllous as in the case of flowers of Polianthes tuberosa.
- The symmetry of flowers is decided by the perianth. When the perianth is bisected over the central axis from any point the symmetrical halves are produced, the flower is called actinomorphic.
What is aestivation - Types of perianth:
- Aposepalous: When the sepals are free, the calyx is called aposepalous.
- Synsepalous: If the sepals are partially or wholly fused, the calyx is called as synsepalous.
- Asepalous: A flower without calyx is called as asepalous
- Sympetalous: The petals are united to form a tubular corolla, called sympetalous.
- Epipetalous: If the petals are free, the corolla is called epipetalous.
Also Read: Living Things Definition and Scope of Microbiology.
What is Aestivation: Types
There are four types of aestivation in plants which are valvate aestivation, twisted aestivation, imbricate aestivation, vexillary aestivation and quincuncial aestivation.
Type of Aestivation | Description | Examples of Flowers |
| Crumpled | Crumpled aestivation in plants is a type of aestivation where corolla's petals overlap in a crumpled and twisted manner in the bud. This results in a wavy appearance of the unopened bud. | Hibiscus rosa-sinensis, also known as Chinese hibiscus |
| Twisted | Twisted aestivation in plants, also known as contorted aestivation or convolute aestivation, is a type of prefloration in plants where the floral organs (petals, sepals, etc.) are twisted or rolled up longitudinally in the floral bud. | Ladyfinger, Cotton, and Hibiscus flowers |
| Valvate | Valvate aestivation in plants is a type of prefloration in plants where the margins of the floral organs (petals, sepals, etc.) are in contact with each other, without overlapping, in the floral bud. | Sweet Pea,Garden Pea, Yellowwood |
| Imbricate | Imbricate aestivation is a type of prefloration in plants where the floral organs (petals, sepals, etc.) are arranged in a manner where the margins of the floral organs overlap each other in the floral bud. This results in a bud that appears to be covered in scales or tiles, like shingles on a roof. | Flowers of Gulmohar |
| Quincuncial | Quincuncial aestivation is a term used to describe the way that the petals or sepals of a flower are arranged in a bud before it opens. In this arrangement, there are five overlapping structures, with two outer structures enclosing three inner structures. | Delonix and Cassia flowers |
| Vexillary | In vexillary aestivation in plants, the largest petal (called the vexillum or banner) is placed on top of the two lateral petals, which in turn cover the two smallest petals at the base. This arrangement is commonly found in flowers of the legume family, such as peas, beans, and lentils. It is also known as descending imbricate or papilionaceous aestivation. | Crotalaria, Dolichos, and Tephrosia flowers |
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What is Aestivation: Placentation in Plants
Placentation in plants refers to the arrangement of ovules within the ovary of a flower. Ovules are the structures that contain the female reproductive cells (eggs) and are attached to the ovary wall by a stalk-like structure called the funiculus. It is the number, position, and arrangement of the placentas within the ovary.
What is Aestivation: Learning Points
- Aestivation in plants refers to the arrangement of sepals or petals in a flower bud before it opens.
- Aestivation in plants plays an important role in protecting the reproductive structures of the flower, such as the stamens and pistil.
- There are several types of aestivations, including vexillary, imbricate, valvate, twisted, and quincuncial aestivation.
- Aestivation in plants can be used as a diagnostic tool to identify different plant species.
- Aestivation in plants is closely related to the shape and size of the sepals or petals in a flower.
- Aestivation in plants can also affect the color and shape of the flower, as well as its fragrance.
- Aestivation in plants is just one of many factors that contribute to the diversity of flowers in the plant kingdom.