The Parts of a plant best known are the roots, leaves, stems, flowers, fruits and seeds. Plants, as well as animals and other multicellular living things, have organs or “parts” that work in unison to allow them to fulfill all their vital requirements and functions..
If we do a quick analysis, we can determine that these living beings are composed of two fundamentally different "portions": an underground one (the one that holds them to the ground) and another aerial (the one that we see growing above the ground).
Hundreds of different animal species depend on both the "aerial" portion and the "underground" portion of different types of plants, not only for food and oxygen, but also for shelter, a remedy for any disease, etc..
In short, a large part of life on the biosphere depends, in one way or another, on plants and their organs, for example:
- The decomposition of dead plant tissues on the soil allows its nutritional enrichment, which in turn favors the subsequent development of new plants..
- Plants also contribute to the reduction of soil erosion, as their roots hold it in place..
- Photosynthesis, one of the most important metabolic pathways for plants, implies that they “absorb” carbon dioxide (CO2) from the environment and release oxygen (O2), which land animals can breathe.
- Man commonly uses the stems, roots, leaves, flowers, fruits and seeds of many plants not only for food, but also to extract compounds with various practical uses.
The underground portion of the plants is represented by the roots. The root is the first plant organ that is observed after the germination of a seed. In many species, the root system represents approximately 50% of their fresh weight.
Roots are vital for plants as they not only help them to hold onto a substrate, but they also work to absorb water and mineral nutrients from it..
In addition, some plants have roots that serve as storage sites for food reserves, mainly carbohydrates, which are available when the plant needs them most..
The roots not only participate in the absorption and conduction of water, but also produce hormones and other substances that regulate the growth of vegetables..
There are two types of root systems: the axonomorphic root system and the fasciculate root system..
- Radical systems axonomorphs they are typical of dicotyledonous species and gymnosperms. These consist of a large main root that "seeks" deep sources of water in the soil, and a series of root hairs and lateral roots that function in the absorption of nutrients..
- Radical systems fasciculated they are generally observed in monocots and grasses. Instead of having a taproot they have many similar adventitious roots, each with its lateral roots and root hairs..
The roots "grow from the tip", thanks to the activity of a group of meristematic cells known collectively as the "root apical meristem", intimately associated with undifferentiated cells known as the "quiescent center" cells..
The structure of a root consists of three "zones" (from bottom to top): the growth zone, the elongation zone, and the maturation or differentiation zone. It has an epidermis that covers it in its entirety and a cortex where the vascular system is located (phloem and xylem).
The aerial portion of the plants is everything that we see growing above the ground, so it includes the stems, the leaves that arise from the nodes of the stem, the flowers that occur in the meristems and the fruits with their seeds, which are the product of sexual reproduction of flowering plants.
The stem and leaves form what is known as the stem system. The external structure of the stems varies greatly between species, however, we can point out some characteristics that are common:
- They have an apical meristem and a series of axillary meristems or buds, often located in the region of the nodes where the leaves are formed..
- They have knots, which are the places where the leaves form and join and from where the lateral branches “come out”. The space between each node along a stem is known as the internode or "internodal region".
- From the apical meristem of the stem, both the new leaves (leaf primordia) and the lateral buds are formed..
The stems are also covered by an epidermis and inside they have what we call “vascular tissue”, which comprises the elements of xylem and phloem, which function in the transport of water and sap..
The stems support the leaves and position them in the direction of the sun's rays to make better use of the energy coming from it. In addition, they correspond to the transport structures of water and processed matter (sap) from the roots to the apices..
The leaves, after the roots, are one of the most important organs of plants, as they are what define these organisms as autotrophic beings. These are the main photosynthetic organs and, in addition, they are essential for gas exchange between the plant and the environment that surrounds it..
During photosynthesis, the leaves function as "antennas" for the perception of the sun's rays. In this process, molecules of water and carbon dioxide are chemically combined in the presence of light energy to produce oxygen and sugars or food reserve substances..
The leaves have, essentially, two parts: the leaf blade (which is the flat and thin part that we see, usually green in color) and the petiole (which is the "stick" that joins each leaf with the main stem or a branch. side).
Although not all plants produce flowers, angiosperms are the largest and most abundant group of plants on earth, and these are the flowering plants..
Flowers are, for this group of plants, the reproductive part through which they reproduce sexually, thanks to the help of entities that we know as pollinators. In addition, the flowers form the fruits and seeds that function in the dispersal of the species.
There are many different types of flowers: these can vary not only in color, shape, size and aroma, but also in the position where they are formed in the structure of the stem..
A hermaphrodite flower, that is, where the male reproductive “part” and the female reproductive “part” are in the same structure, has the following “parts”:
- Peduncle floral: the portion of the stem that joins the flower with the plant
- Sepals Y petals: the modified leaves that protect and nourish the reproductive part and that "attract" pollinators, respectively.
- Stigma, style Y ovary: the “female” reproductive part
- Anthers Y filaments (stamens): the “male” reproductive part
The fruits are the structures that protect the seeds and that are formed after pollination in the place where the flowers were. Many of them have very nutritious external fleshy structures and this usually attracts animals that, when eating them, take the seeds with them, dispersing them.
As is true for flowers, there are many different types of fruits, with very different structures, textures, fleshiness, smells and flavors (concentration of sugars and water)..
The seeds, finally, are the dispersal structures of plants, of sexual origin. These protect the embryo that has developed after the fusion of the female and male gametes (zygote formation) of different plants.
In addition to protecting it, the seeds support the life of the embryo when, when germinating, it activates its metabolism and requires food.
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