Plants are a large group of living beings, made up of eukaryotic cells that carry out the process of photosynthesis. In this group we find algae, ferns, mosses, trees, herbs and shrubs. All have particular characteristics, however, we can distinguish in most of these four main organs:
Root: where the plant gets water and minerals.
Stem: gives support to the plant.
SheetWhere do they capture light for photosynthesis?
Flower: responsible for sexual reproduction in plants that is transformed into fruit and seed.
Estate
The roots are the part of the plant that provides fixation and nutrition. Some plants have their roots buried in the ground, which can go from a few centimeters to meters, searching for water and the elements for growth and development. Other plants have aerial roots with which they cling to a support, such as orchids.
Some plants lack roots. This is the case of bromeliads, plants that only survive in very humid and rainy environments, so that water can be absorbed by the leaves.
Roots have the following functions:
anchor the plant: the root stabilizes and fixes the plant in a substrate or base, in such a way that they orient the stem, leaves and flowers towards the sun and pollinating agents.
Absorb water and chemicals: the elements that the plant needs for its activities, such as potassium, phosphorus and magnesium, are found in the soil and are absorbed together with the water through the roots.
produce hormones: in the roots the hormones gibberellin and cytokinin that regulate the growth and development of shoots are synthesized.
store carbohydrates: Some roots serve as a storage for sugars, such as carrots, beets and radishes, which are then used by the plant to survive during the winter. Human beings take advantage of these roots to feed ourselves.
root structure
apical meristem zone: is the tip of the root. In this region growth occurs, as it has the ability to push through the soil. The tip is protected by the cap, a thick layer of cells that is constantly multiplying and secretes a lubricant that facilitates the passage of the root tip through the soil.
elongation zone: Above the tip of the root is a region where cells undergo division and expansion.
hairy area: region where hair-like structures are concentrated. Root hairs increase the area of absorption and last a few days, after which they degenerate.
root types
The two main root systems are the fibrous roots, as in the leek, and the taproot, as in the dandelion.
There are two systems of root types:
Main root: is the system where there is a central main root from which other roots branch. The taproot develops from an embryonic root called the radicle, present in the seed. It is present in trees, in bean plants, tomatoes and roses.
adventitious roots: or fibrous root system, found in monocotyledonous plants, such as onion, corn and gladioli. It is characterized by presenting independent root threads.
modified roots
Many plants have roots that are out of the ordinary:
storage roots: In plants that live for two years, the roots are the permanent organs, so stored carbohydrates are used to produce new shoots in the spring.
Support roots: They are roots that are generated from the stems, as in the case of some palms, in corn, in Ficus and in mangroves.
aerial roots: Many orchids live on other plants, so their roots have to reach out and grab onto the bark of trees.
symbiotic roots: some roots establish a symbiotic relationship with soil fungi, forming mycorrhizae. Others, such as the roots of legumes, form nodules with bacteria of the genus Rhizobia, capable of capturing nitrogen from the air and transforming it into ammonia, which the plant can then use to produce amino acids.
haustorial roots: are roots of parasitic plants, that is, plants that live at the expense of another plant.
stems
The stem is the organ that supports the leaves, flowers and fruits. It belongs to the shoot system of the plant and connects the rest of its parts with the roots. Most are on the surface, but there are some, like potatoes, that also grow buried in the ground.
The main function of the stems is to raise the leaves so that they can be better exposed to sunlight. Also through the stem material is conducted to and from the leaves. In addition, we eat the stems of some plants, for example, potatoes and asparagus.
Among the characteristics of the stems we can mention:
Size: the stem can measure a few millimeters, like some mosses, up to tens of meters, like redwoods.
Diameter: It is also variable, they can be as thin as rice stems, or as thick as the tree of Santa María del Tule, in Oaxaca (Mexico) that measures 14 meters in diameter.
Structure: the stems can be herbaceous, such as corn or wheat, or woody, such as cork oak and pine trees.
Shape: the stem can be single, like the palm tree, or branched, like the apple tree.
stem parts
In the stem of many plants we can distinguish the nodesthe places where the leaves meet, and the internodes, the regions between nodes. The leaves are attached to the stem by the petiole.
If we cut a stem widthwise in angiosperms we can see the epidermis, cortex and vascular tissues. The epidermis of the stem is a single layer of cells that cover and protect the tissue below. Woody plants have a tough, waterproof outer layer of bark cells that provides added protection.
The xylem and phloem make up the vascular tissue of the stem. The xylem transports water from the bottom up in the plant, the phloem collects the sugars and amino acids produced in the leaves.
stem parts
modified stems
rhizomes: are horizontal stems that allow the plant to extend below the surface, such as bamboos, ferns, irises and ginger.
tubers: They are horizontal and grow for a short period of time. Its function is to store nutrients, as in the case of potatoes or potatoes.
bulbs: they are short shoots, some have fleshy leaves, like onions and garlic, others have papery leaves, like saffron and gladioli.
stolon: are extensions of the stem, as in strawberries.
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Leaves
The leaves are the organs of production of photosynthesis. During photosynthesis, they absorb carbon dioxide and convert it into carbohydrates using light energy.
In addition to the photosynthetic function, the leaves offer protection to the plants, through the thorns and the scales of the cocoon; support by tendrils; storage as the fleshy leaves of the bulbs and even obtaining nitrogen, in the case of insectivorous plants.
The leaves are a source of food for the vast majority of living beings. Humans eat leaves like lettuce, spinach, cabbage, artichokes, and onions. We use basil, bay leaf, oregano, parsley and mint as spices.
Among the characteristics of the leaves we have:
assorted shapes: lanceolate, like the willow, linear like the wheat, needle like the pine, elliptical like the rose, reniform, like the cyclamen.
margins: may be continuous, serrated, dentate, lacerated, or divided.
Colors: We associate leaves with the color green, but they can also take on other colors, such as yellow, red, or purple.
Texture: there are leaves that are smooth like the banana leaf, silky like verbasco, or sticky like the gardener’s love (Galium aparine).
Size: they can be as small as the moss, or huge, like the water lily.
Leaf: It can be simple, like the leaves of an oak, mango or pepper, or compound like the leaves of a rose or jacaranda.
leaf structure
Internal structure of a leaf.
We can distinguish two parts in the leaf: the petiole and the blade. The petiole is the transition between the stem and the leaf blade, which is the extended part we recognize as the “leaf”.
The leaf presents the following internal structure:
Epidermis: thin flat layer that serves to capture light and perspiration. In the lower epidermis, stomata prevail, pores that open to the external environment and through which the movement of gases and perspiration occurs.
mesophyll: includes the internal tissues between the epidermis. In an upper layer are the palisade parenchyma cells where photosynthesis occurs; below is the spongy parenchyma.
vascular tissues: They are found within the mesophyll and are in charge of distributing the water that comes from the xylem and the sugar load within the phloem.
Types of modified leaves
The tendril is a modified leaf that helps support climbing plants.
succulent leaves: they are thick and fleshy leaves that favor water conservation. They prevail in desert conditions and are characteristic of the families Chassulaceae (Kalanchoe and sedum), Portulacaceae (portulaca and Lewisia) and Aizoaceae (ice plant).
sclerophyll foliage leaves: They are resistant, stronger and more durable leaves, like the leaves of the Agaves and Yucca.
coniferous leaves: They can be simple, needle-like, as in pine, fir, and spruce, or small and flat with scales, as in cypress and juniper. These plants are evergreen because they do not lose their leaves in the winter.
thorns: they are modified leaves that sprout in the auxiliary buds. It is needle-shaped, which helps protect the plant against herbivores.
scales: At the tip of shoots or buds, these leaves protect the future growth of the plant.
tendrils: are leaves that grow as spirals on climbing plants, such as peas, cucumbers, passion fruit or vines. They have cells capable of detecting contact with objects, which causes them to roll up. In this way they support the plant.
insect traps: are modified leaves with the capacity to trap and digest insects in habitats poor in nitrates and ammonium.
Flower
Flowers are the sexual reproductive organs of plants. Some plants have flowers with exclusively female or male parts, such as corn. Others keep the male and female parts in a single organ, like the apple blossom.
The function of the flower is to ensure successful pollination. Pollination is the process of transferring pollen grains from the stamen to the stigma, where they germinate and form a tube through the style to the ovary. Sperm cells are transferred from the pollen grain down the tube to the ovary, where they fertilize the egg.
In the flowers we can distinguish the following structures:
sepals: protect the other parts of the flower as they develop.
The petals: attract pollinators after the sepals are…