Plants in nature have different biological or life forms, depending on their relationship with their environment, these are: trees, shrubs or herbs. This post has the objective that you learn about plants and specifically about the Types of Trees. Giving answers to what a tree is, its parts, characteristics, uses, as well as examples of tree species.
Types of Trees and their Characteristics
Let's start by clarifying what trees are, some authors agree in pointing out: that trees are terrestrial, woody plants, of medium or tall height, with a trunk and ramifications from 1 to 4 meters high, which extends up to the upper end, this branching may be more or less developed. Trees are also characterized by the robustness of their trunk, the breadth of their branches and their variable longevity.
According to this definition of trees, they are, in addition to large, medium or small plants that have the aforementioned characteristics, but also some species of cacti, palm trees, tree ferns and even some frailejones (plants found in the Andean Cordillera).
As previously mentioned, their relationship with the environment determines the way of life of plants (trees, bushes or herbs), so it can be said that the shape of trees is also influenced by their relationship with various environmental factors, such as the climate and the soil. In view of this, trees play a primordial role in nature.
Depending on this relationship, trees can be very long-lived, ranging from a few decades to as much as five thousand years, like the bristlecone pine. They can measure 4 meters or more than 100 meters, like the Eucalyptus regnans, some specimens of which are known to reach 140 meters in height. Likewise, some have slender trunks, while others, like baobabs and Montezuma cypresses, have trunks with diameters of up to 30 meters.
The elements of the trees
The elements of the trees are represented by the root, trunk and crown, coupled with the balanced growth of these three elements during their development, with the aim of maintaining a constant proportion of their parts. This synchronized development of its parts is what they call the architecture of the tree. This architecture of the tree is the morphological manifestation, which has been its visible aspect.
The roots
The roots are the support and sustenance parts of all plants, because their main functions are the absorption of water and mineral salts that serve as hydration and nutrition for plants and in this case trees. They are also supportive to secure the tree to the ground and prevent weather conditions such as the wind from knocking them down, for this reason the trees have a root system that usually extends horizontally, intermediate and pivoting or deep. Its volume is similar to the volume of the tree canopy.
The log
The trunk has a woody constitution that usually branches off at a certain height from the ground, which is known as a cup, in this cup the foliage (leaves) is formed, and the flowers and fruits develop. Inside the trunk is the xylem, which has been the system that conducts water from the roots to the crown (branches, leaves, flowers and fruits). And also by the phloem, which is the part of the vascular tissue through which water and nutrients pass in the opposite direction to the xylem. Both the xylem and the phloem give the lignified consistency to the stems of the trees.
The cup (branches and leaves)
The crown of the trees is made up of the branched part of the tree, that is, the branches and leaves and is found in the upper part of the trees. Leaves are the specialized organs of plants, in this case trees that absorb minerals found in the atmosphere, solar energy, and transform it into sugars to nourish the plant and release oxygen into the atmosphere. Remember trees are autotrophic beings, which produce their own food. This plant food is produced through a biochemical reaction called photosynthesis.
Flowers
In flowering plants are the reproductive organs of plants and therefore trees. They have four parts: the calyx, the corolla, the stamens, and the ovary or gynoecium.
The calyx of the flowers is what can be seen with the naked eye and they are the sepals, which are the green leaves that protect the flower. The corolla is the most showy part of the flowers, it is made up of several floral sheets of different colors and quantities called petals. The reproductive organs are the stamens and the ovary or gynoecium, both of which are located in the center of the flower.
The fruits
Once the flower is fertilized, the fruits are formed. In the fruits are the seeds, the fruits vary according to the species of the plant. The fruits can be fleshy or dry. Fleshy fruits are for example, apples, peaches, oranges. On the other hand, nuts are: acorns, walnuts, hazelnuts, among others.
Types of Trees by Size
In nature there are about 100 thousand species of trees, most of these growing in the tropical regions of the planet, adapting their morphology and physiology depending on the climatic and edaphic conditions of each place. These can be seen growing in natural places and in ecosystems intervened by man such as cities.
Depending on its size, it can be said that there are two main arrangements, these are: Parasol or polyaxial type and candelabra or monoaxial type. These arrangements of the trees is a response to solve the problem that the leaves receive the greatest possible insolation during the day. This response keeps a balance with the availability of subsoil water, and also with the eco-physiology of the plant.
Parasol or polyaxial shaft
In this type of trees, the branches separate from the mother branch at a great distance from the ground surface and extend to that same height. This way of arranging the branches allows all the leaves of the tree canopy to receive enough solar radiation during the day. It can be seen in the trees of the Fabaceas family, for example: carob.
Candelabra or monoaxial type tree
In this type of tree, the main branch does not divide until a great distance from the base. The upper branches, after initially being arranged obliquely, straighten and quickly become parallel to the main branch, as is the case with trees of the Burseraceae family, such as the frankincense tree ( Boswellia sacra ), possibly the tree from which the frankincense referred to in the Bible as a gift by the Magi came.
A modification of this type of branch growth, candelabra type, is the case of tree species that suppress their ramifications and the rapid growth of the stem causes the few branches to be placed at the apex of the tree crown. For example, tree ferns, palm trees, Cycas, Guapuruvu, among others.
Types of Deciduous and Evergreen Trees
Trees, depending on the permanence of their leaves during their development and time of year, are called deciduous or evergreen. In tropical regions, the loss of its leaves occurs due to the absence or abundance of water and occurs during the dry period, due to low rainfall. In countries with a temperate climate, they occur in the autumn and winter seasons, where weather conditions are adverse.
deciduous trees
The word deciduous is a compound word that is formed from the Latin root “caducus”, which means fallen, and “folium”, which means leaf. This means that a deciduous tree or a type of deciduous tree means that it is a tree that loses its foliage at the end of a growth cycle, as a physiological response that allows the rational use of absorbed nutrients in adverse conditions. climate and water, especially in the autumn and winter seasons in temperate climate regions and the dry season in tropical regions.
In countries with temperate climates, the fall of the leaves in the autumn season is very striking, this process varies depending on the rains or even during the winter season, as observed in the maple tree. This leaf drop is a beneficial adaptation, since the types of trees that lose their leaves will not have to spend energy during the winter protecting their leaves from freezing.
In tropical regions, there are places such as deciduous forests where the occurrence of rains is very strong during one time of the year and then a very marked dry season arrives. In these regions, deciduous trees shed their leaves so that the tree conserves as much water as possible during the dry season. Leafless trees absorb groundwater during drought.
In the tropics, many deciduous trees lose their leaves during the dry season, and it may also happen that in tropical humid forests, which are places with sufficient precipitation, environmental humidity and availability of groundwater, there are species of trees that remain evergreen.
Deciduous Tree Species
Ginkgo biloba: This tree is also called the "fan tree" because of the shape of its leaves. This slow-growing, dioecious species has a pyramidal crown in male specimens, while female specimens have wider crowns. Its leaves are deciduous and resemble small fans.
Lagerstroemia indica: This is a small, multi-stemmed tree, about 8 meters tall. Its trunk has smooth, prominent, pinkish-gray bark. Its leaves are dark green and fall during the autumn season. Due to the beauty of its white, pink, crimson, or mauve flowers and stems, it is used ornamentally.
Castanea sativa: This tree grows to between 25 and 30 meters tall, with a short, straight, and thick trunk about 2 meters in diameter. The bark changes color as it matures, going from grayish or brownish to dark brown. Its leaves have a rounded base, are asymmetrical, and have serrated edges. Its fruit is edible and was once an important food source in southern Europe.
Albizia julibrissin: Commonly known as the Persian silk tree (Albizia julibrissin), this deciduous tree grows to about 15 meters in height and has a broad crown and dark greenish-gray bark. Its fruit is a legume. It is native to Southeast and East Asia, from Iran and China to Korea. It was introduced to Europe in the 18th century for ornamental purposes.
Types of Evergreen Trees
In contrast to deciduous trees in nature, evergreen trees can be observed, ie evergreen trees or trees with evergreen leaves. In temperate regions these trees keep their leaves regardless of the season of the year. This type of tree renews its leaves continuously, there are two types of trees with evergreen leaves.
Broadleaf evergreen trees: These are trees whose leaves have broad leaflets that remain attached to the branches year-round. They are very leafy and therefore produce ample shade wherever they grow. Broadleaf evergreen trees are generally found in tropical and equatorial regions with high temperatures and abundant rainfall.
Evergreen trees with scale-like, needle-like, or acicular leaves: These are trees whose leaves or leaflets are narrow and elongated. These types of trees typically grow in areas with cooler temperatures. Among these evergreen trees are conifers, whose leaves are leathery and coated with resin. Specialists have recorded around 600 species of conifers, making them one of the oldest and tallest trees in nature. Some examples of this type of tree include pine, cypress, and cedar, among others.
They differ from the types of deciduous trees in that evergreen trees do not change the color of their leaves and it usually happens that the period of loss of their leaves is very long, and sometimes it even occurs every 17 years. Evergreen trees are known that are endemic to the tropics and equatorial regions and others are endemic to cold regions of the continents of: Asia, America and Europe.
Among evergreen trees, the bristlecone pine ( Pinus longaeva) stands out. It is found in a protected region of the high mountains of the southeastern United States to prevent pruning. It is believed to live for more than 5.000 years.
Evergreen Tree Species
Quercus ilex: Commonly known as holm oak, this medium-sized tree is native to the Mediterranean. It can reach up to 30 meters in height, or grow in a shrubby form depending on rainfall. These trees are cultivated for their fruit, called acorns.
Magnolia grandiflora: The magnolia tree, native to the United States, has a pyramidal crown. It grows to about 35 meters in height and has simple, ovate, evergreen leaves that remain until new leaves appear in spring. It is used as an ornamental tree.
Arbutus unedo: This tree grows to between 4 and 7 meters tall. It is distributed from the Mediterranean region, from France to Ukraine. It is commonly known as the strawberry tree. Its leaves resemble those of the laurel, being elliptical and dark green. It is native to Spain; however, in some parts of the country, it behaves as an invasive species. It is used ornamentally.
Coniferous evergreen needle-like leaves
Conifers are the most important group of gymnosperms. They were once a dominant group of trees in almost all regions, now they have been displaced by angiosperms. They are called conifers, because their seeds are found in a specialized structure called cones. To reproduce, conifers produce male and female cones on the same plant. Conifers date from the Carboniferous, about 300 million years. Currently its use is ornamental, it is used for paper pulp and construction.
Abies pinsapo: This is a species of fir in the Pinaceae family. It is a pyramid-shaped tree, about 30 meters tall, and its natural habitat is the Iberian Peninsula. Its needles are sharp and rigid. It produces cones that release pine nuts when mature.
Taxus baccata: Commonly known as the black yew or common yew, it is native to Western Europe. It is a conifer that grows to about 30 meters tall, with a broad, pyramidal crown and horizontal branches. It can live for up to 5.000 years. The entire plant is poisonous, except for the aril that covers the fruit. Due to its longevity, it has been planted in cemeteries since ancient times. It is also used as an ornamental tree.
Cedrus atlantica: This is a long-lived tree, native to the Atlas Mountains of Algeria and Morocco. It grows to about 30 meters tall. Its crown is conical, its trunk is straight with smooth bark, and it has evergreen leaves with bluish-gray needles.
Sequoia sempervirens: Commonly known as the coast redwood or California redwood, this very long-lived tree can reach 2.000 to 3.000 years in height and 7,9 meters in diameter. It is a distinct species from the 85-meter-tall giant sequoia ( Sequoiadendron giganteum ) and the shorter, 45-meter-tall dawn redwood ( Metasequoia glyptostroboides ). The name "Sequoia," by which it is known worldwide, was given in honor of the Cherokee chief Sequoyah.
How Trees Reproduce
In nature, the first plants that existed are part of the Gymnosperms Division, which are plants without flowers and among the trees that we know and are representatives of the gymnosperms are the conifers, which are called that because their reproductive structure is called cones. and the ginkgo, among others. Due to plant evolution today, most of the plants and among them the trees that exist on the planet are the Magnopliophyta Division (formerly angiosperms), which are plants with the presence of flowers.
The reproductive organs of plants are found in flowers. In them is the ovule or potential seed in the ovary, the fact of being enclosed within the flower, the differences of gymnosperm plants (plants with naked seeds because they do not have flowers). In nature, most plants, including trees, reproduce by seed and few by cuttings or cuttings, after a strong wind has split the tree and its young branches take root in the ground.
Reproduction by seeds
With the intervention of man, by observing how trees are born in nature, they have collected their seeds and perfected the method of reproduction of trees through seeds and also by trial and error they have managed to reproduce trees in another way, namely : by cuttings or cuttings, by air layering and in vitro cultures. To reproduce them by seeds, depending on the type of seeds, one of these preparation and sowing methods can be applied.
Direct sowing of seeds: The seeds are collected from the trees in the field or from their fruits and sown in seedbeds.
Soaking the seeds: Depending on the hardness of the seeds, or it may also be to remove the mucilage (viscous texture that looks like rubber), the seeds are placed inside a container with water for about 24 hours.
Cold stratification: The seeds are placed in the refrigerator for two to three months at a temperature between 4 and 6 °C, then removed and sown in the seedbed. This seed preparation method is used for trees that naturally grow in temperate climates.
Hot stratification: This is a method of preparing seeds in which they are placed in heat for a period of time before sowing.
Thermal shock method: In this method, the seeds are immersed in boiling water for one second, then transferred to a container of room-temperature water and left there for 24 hours. Afterward, the seeds are sown in a seedbed. The purpose of this method is to create micro-cuts in the seed coat or outermost layer. These micro-cuts allow the embryo to hydrate and the seed to germinate. This method is applied to small seeds such as those of Acacia sp.
asexual reproduction
This type of reproduction is not produced by seeds, in nature it is produced by the development and growth of a new shoot from the base or from the roots of the plant, these develop as an independent tree. In nature, when this method of reproduction occurs, the juvenile tree will replace the adult tree from which they were born.
In nature, with this type of reproduction, the original tree marks its territory, since the trees that are born in this way, the new trees, are identical in their genetic characteristics. This type of reproduction guarantees genetic continuity, if the environmental conditions are maintained, this type of reproduction will be an advantage. However, if environmental conditions vary, these plants are unlikely to adapt.
Propagation by cuttings: This is known as asexual reproduction because it does not use seeds, which are the sexual and reproductive organs of plants. In this method, young branches are cut from trees (this method allows for faster reproduction of new trees). The branches cut to produce cuttings are between 4 and 7 centimeters long. Depending on the species, they will take between two and several months to root.
Grafting Method: In this method, a branch is cut from a tree, which becomes the plant to be reproduced or propagated, and inserted into a branch of a mother tree or rootstock. The graft will grow as part of the plant. This method is used for many fruit trees, allowing different fruits to be obtained from the same tree, or improving the quality of the fruit.
Benefit of Trees in Nature
Trees are a source of life in nature and are autotrophic organisms, capable of transforming inorganic components into organic ones and producing their own food to nourish themselves and grow. Trees form carbohydrates from carbon dioxide and water through photosynthesis and the absorption of solar energy. They are the only living beings that fix carbon dioxide (CO2 ) from the absorption of solar energy, producing organic matter and releasing oxygen into the air.
They participate in the food chain as primary producers. In the food chain it is made up of primary producers, consumers and decomposers; through it flows energy that begins with the use of solar energy and ends with the total decomposition of organic components. The energy flows in one direction, from the sun it is absorbed by the primary producers, they pass to the consumer organisms or heterotrophs and then culminate in the decomposer organisms.
In addition to purifying the air, trees provide oxygen and produce food and shelter for wildlife; they protect soils from erosion; regulate temperature and humidity; They regulate the hydrological regime by allowing the best use of rainwater. Raw material such as: wood, cellulose, cork, resin, flowers and fruits are obtained from the trees. In addition, trees are sources of food for their fruits: such as chestnuts, walnuts, pine nuts, apples, mangoes, medlars, citrus fruits, among others.
Economic Importance of Trees
Trees have played various important roles in human life, whether in religion, witchcraft, or industry. As a cultural and religious symbol, conifers, used as Christmas trees, serve as an example. Similarly, from a philosophical and cultural perspective, the Ficus religiosa, the sacred tree, is considered the tree of wisdom.
Forest trees: Since ancient times, humans have used trees in various ways. They have been used as forest trees for their timber and derived products. Trees provide wood as a raw material for building construction and furniture production. Tree pulp is used in the paper industry.
Fruit trees: Other trees are used as fruit trees, to take advantage of the edible fruits in the food industry and some of these are cultivated accordingly.
Ornamental trees: Another way to utilize them is aesthetically, by adorning streets, parks, and gardens. These are called ornamental species and are part of urban arboriculture. In cities, trees are planted in streets, parks, and gardens for ornamental purposes, as well as to provide landmarks for rest, a cooler microclimate, and recreational activities for citizens.
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