A flower is one of nature’s most amazing creations. And from a biological point of view, this organ performs an essential function - it provides generative propagation of plants. From our article you will learn about its structure, variety and structure of a simple perianth.
What are generative organs
The flower is a modified shoot, which is limited in growth and shortened. Its main parts are four. This is the pedicel, receptacle, stamens and pistils. The first two parts are called sterile. This means that they do not participate in the process of sexual reproduction of plants. Pestle and stamen are fertile parts. They contain germ cells. As a result of pollination and fertilization, a seed is formed, which is located inside the fetus. So there is sexual reproduction of flowering. Thus, the generative organs include a flower, a seed and a fruit. Their presence is characteristic only for representatives of the Angiosperms department.
Since the flower is a modified shoot, it has all the parts inherent in the aerial parts of plants. So, the pedicel is an internode. On it may be leaflets called bracts. Sedentary flowers are often found in nature. They are attached directly to the stem.
The expanded part of the pedicel is the receptacle. It can be flat, concave or convex. In plants that are pollinated by the wind, the flowers are usually dioecious. This means that they contain either stamens or pistils. Such flowers have an underdeveloped corolla, and in some cases are deprived of it. This makes the wind dusting process more efficient. If dioecious flowers are located on one individual, the plant is called a monoecious. These include oak, birch, alder, aspen, sedge. In dioecious plants, unisexual flowers are found on different individuals. This willow, poplar, sea buckthorn, aspen, sorrel.
Perianth structure
Consider the structure of the sterile part of the plant. This perianth is simple and double. It consists of a whisk and a cup. This structure is called double, or heterochlamide. Its presence is a systematic symptom. Double perianth have all dicotyledonous plants. For example, peas, apple, eggplant, aster, sunflower. In nature, most of these plants.
The composition of a simple, or homohlamide perianth includes either a corolla or a cup. It is characteristic of monocotyledonous plants. It includes the family Onion, Lily, Cereal and others.
Whisk
This is the brightest part of the perianth. A whisk is a collection of petals. In size, it is much larger than a cup. Corolla is painted in different colors. Bright petals are necessary for the plant to attract insects. In wind-pollinated species, the corolla is inconspicuous or reduced.
The shape of the corolla is also quite diverse. For example, in legumes, the petals are morphologically different. The upper one is the largest. On the sides are two free petals, and the lower ones are partially fused. Outwardly, they look like a sail, a boat and oars or a butterfly that folded its wings. Therefore, the legume family is also called the Moths.
In nightshade plants, all the petals fuse together, forming a tube with a pharynx. It ends with free teeth. The number and shape of the petals is also a systematic feature. So, representatives of the Rosaceae family have five, Cruciferous - four. And in the Astrovs, up to one and a half thousand small petals are part of the inflorescence.
Cup
Another part of the perianth is a set of sepals. Their main function is protective. It is carried out during the formation of the bud. At this time, the sepals completely cover the flower. In an adult plant, the calyx is the photosynthetic part. Along with leaves, it additionally provides plants with organic substances.
Sepals consist of the main tissue - the parenchyma, in which the conducting bundles are located. Outside is the integumentary tissue - the epidermis. The sepals are colored green. Being derivatives of bracts, a simple form and small size, outwardly they resemble vegetative ones.
According to the structural features distinguish separate and congenital cup. In the first case, the sepals attach freely and are located at a certain distance from each other. For tobacco and nightshade, the cup is leafy. Its components are the tube, teeth and lobes, the number of which is equal to the number of sepals. Cups of this type may have a funnel-shaped, bell-shaped or tubular shape. In sage and Scutellaria, this part of the perianth consists of two unequal parts. In this case, it is called a two-lip. Sepals of mallow and wild strawberries form two circles. During bud formation, this feature provides added protection.
In some plants, the sepals fall off or bend as the flower blooms. And among representatives of some families, they mutate. At the same time, the cup performs an additional function - it distributes seeds. For example, in the Yasnatkovye, it turns into a box, and in the asters, it becomes a crest.
The cup is not always green. Examples of such plants are wildlife and hellebore. Their whisk is very reduced. Therefore, its function is performed by a bright perianth.
What is a simple perianth in biology
The main feature underlying the classification of this part of the flower is the presence of two main parts - the corolla and calyx. Depending on this, a complex and simple perianth is distinguished. In the first case, it is represented by both petals and sepals. In most cases, the structure of the simple perianth is represented only by a nimbus. Consider its structure on specific examples.
What flowers have a simple perianth
The structure and number of parts of the flower is an important systematic attribute. So, a simple perianth is a characteristic feature of the class Monocotyledonous. A striking example of such plants are tulip and lily. Their simple perianth is nothing more than a large and bright corolla. Such flowers easily attract the attention of insects. The pleasant aroma of flowers also contributes to this. The fact is that in the integumentary tissue of the petals, which is called the epidermis, contains essential oils.
So, in our article we met with such a concept as a simple and double perianth. In the first case, this structure consists of a calyx or corolla. In flowers with a complex perianth, both of these parts are developed.