PERIANTH: CHARACTERISTICS, PARTS, FUNCTIONS - BIOLOGY - 2024

The perianth is the set of sterile pieces that form the floral envelope and its function is to protect the sexual organs of the plant. It is made up of two whorls, the calyx and the corolla, which may or may not be present; and when they are, their shape, color and arrangement can be highly variable depending on the species.

The flower is formed by a set of modified leaves, and represents the reproductive system of a group of plants called phanerogams. In addition to the two perianth whorls, the flower is also made up of two other whorls, the androecium and the gynoecium, which constitute the reproductive parts of the flower.

Details of the perianth of the Aloe mossurilensis flower. Taken and edited from: Ton Rulkens from Mozambique.

Only some hermaphrodite flowers present the four flower whorls, which are called complete flowers. Some of these whorls may be missing in the rest of the flowers.

characteristics

The fundamental characteristics of the perianth are that it constitutes the infertile part of the flower, and that it is located externally protecting the fertile part of it, since, apart from these characteristics, its constituents are highly variable in terms of presence, absence, quantity, type and distribution, among others.

Classification of flowers according to the characteristics of the perianth

Aperiantadas

They are flowers that lack perianth. They are also known by the name of naked or acclaimed. In this case, the fertile elements of the flower (androecium and / or gynoecium) are protected only by the bracts. Examples of this type of flower are the willow flower and the corn flower.

Periantadas

The plants that do present perianth are thus called; also known as clothed or clamideas. Most of the flowers are of this type, such as tomatoes.

-According to the conformation of the perianth

Monoclamide

Also called apétalas because they only have calyx (for example the Urticaceae). In some cases, the elements of the calyx (sepals) have a shape and color similar to that of petals, for example in the genus Clematis (Ranunculaceae), where the flowers have petaloid sepals.

Diclamides

They are those flowers that present the two infertile whorls of the perianth. When both whorls are present, these in turn can be similar to each other, or on the contrary, they can be easily differentiated, for this reason the diclamideas can in turn be subdivided into the following groups.

Homoclamide

They are flowers that present the two similar perianth whorls, receiving the name of perigonium, made up of tepals. Perigonium pieces can resemble sepals, or flower petals with two different whorls. In the first case, we speak of a calicine perigonium; while in the second case it will receive the name of corolino perigonium.

Heteroclamideas

These are flowers with both whorls of the perianth clearly distinguishable.

Parts

-Chalice

It is the outermost floral whorl and its elements, called sepals, are generally green and close to a leaf. In homolamide flowers they are indistinguishable from the elements of the corolla (tepals).

In plants of the Asteraceae family, the elements of the calyx are widely modified, presenting the appearance of mushrooms or bristles. They constitute a structure that receives the names of vilano or papus.

In other cases, the sepals may be covered by filiform structures of a glandular nature, as occurs with plants of the Solanaceae family.

Types of calyces according to the degree of fusion of the sepals

Dialysepal

The elements of the chalice are completely separated from each other, as observed, for example, in the poppy.

Gamosépalo

Type of chalice in which the sepals are united, for example in the carnation. In this type of calyx, the sepals are not united in their entirety, but leave their distal portion free, which is known as the limbus. The united portion of the sepals is part of the tube, while the place where they begin to separate is called the throat.

Types of calyces according to their duration

Ephemeral

Also known as fleeting, it is a chalice that detaches from the flower as soon as it opens.

Deciduous

It is the most frequent type of calyx, it remains in the flower until after pollination.

Persistent

Calyx that never comes off and even accompanies the fruit.

-Corolla

Inner floral whorl of the perianth. It is composed of anthophiles that are generally very strikingly colored and are larger than the sepals. These anthophiles are called petals.

The basal portion of the petal, which is attached to the receptacle, is called the nail, while the widest and generally colored part is called the lamina or limbus.

As with the sepals, the petals can be separated (dialipethala) or united (gamopetala). In the case of the gamopetal crown, the same parts are observed as in the gamosépal calyx.

The shape of the gamopetal corolla is highly variable, and can be found in a cylindrical (tubular), a funnel (infundibuliform), a bell (campanulate), or a tongue-shaped (ligulate) limbus, among other shapes.

-The calligulum

In some plants, such as many Malvaceae and Pasifloraceae, a set of sepal-like leaves may occur on the flower stalk and below the calyx. This set of leaves is called a calígulo or sobrecalyx. This structure does not constitute an additional floral envelope, and its function is to protect the calyx.

Diagram of a mature flower. Taken and edited from LadyofHats.

Features

Chalice

The main function of the calyx is the protection of the other flower whorls, both from browsing by animals that eat flowers, and from mechanical damage caused by pollinators.

In some cases, the protective function is maximized by the presence of trichomes, tannins or by the secretion of waxes.

Another function of the corolla, in some species, is the attraction of pollinators, the sepals acquiring showy colors, as occurs with the petals. The secretion of sugary substances, by structures called nectaries, also helps attract pollinators.

In other species, the calyx may have hook-shaped structures or spines, or the sepals may acquire winged forms, to help seed dispersal, by adhering to animals, in the first case, or by the action of the wind in the second case.

Corolla

The main function of the corolla is to attract pollinators to ensure successful reproduction. This attraction can be visual or chemical. Visual attraction is achieved through the colorful colors and the various forms that this whorl can take.

The chemical attraction is achieved thanks to volatile elements produced by the flower, which in most cases give it a pleasant fragrance. However, carrion flowers give off strong and nauseating odors that attract flies, which will act as pollinators, such as the flowers of species of the Apocynaceae family.

Additionally, the petals, like the sepals, provide protection to the fertile whorls of the flower.

References

1. MW Nabors (2004). Introduction to Botany. Pearson Education, Inc.
2. M. Gealmbi. Chalice: characteristics, parts and functions. Recovered from lifeder.com.
3. M. Gelambi. Corolla: characteristics, parts, functions. Recovered from lifeder.com.

   Perianth. Recovered from ecured.com.

4. Perianth. On wikipedia. Recovered from en.wikipedia.com
5. Simpson, Michael G. (2011). Plant Systematics. Academic Press.
6. H. Beentje & J. Williamson (2010). The Kew Plant Glossary: ​​an Illustrated Dictionary of Plant Terms. Royal Botanic Gardens, Kew: Kew Publishing.