"Strange" Plants Near the Subtropical Sunshine Forest

"Strange" Plants Near the Subtropical Sunshine Forest

Subtropics refers to the northern and southern parts of the tropics to the edge of the temperate zone. Its climate is characterized by the transition between tropical and temperate zones. There are roughly three kinds: humid subtropical forest climate, Mediterranean climate and subtropical desert climate. There are different vegetation and plants here because of the different climate.

Sunshine forest is different from tropical rain forest.

The so-called light-leaved forest is one of the important forests in subtropical areas. Warm in winter and hot and humid in summer; The average temperature in Leng Yue is about 20℃, and the average temperature in the hottest month can reach 27℃. The annual precipitation is above 1000mm, with the most precipitation in summer and less in winter, but there is no obvious drought and the air humidity is high. In this climate, the leaves in the forest will not fall in winter. Because the air humidity is high and the light is not strong, the leaves are irradiated by light sources in many directions, so they get more light, so they are called illuminated leaf forest.

Sunleaf forest is different from tropical rain forest: the trees in the forest are relatively simple. Tropical rain forest has no plate-shaped roots and leaves have no dripping points (the bodhi leaves of tropical rain forest have a long dripping point, which can play a role in drainage during heavy rain and prevent rain from staying on the leaves); There are no flowers on the stems (all banyan trees in the tropical rain forest have stem flowers, and the flowers and fruits of jackfruit grow on the trunks and branches). Although there are many lianas in the leaf forest, it is extremely difficult to see the big lianas. The diameter of vines is so small that they can't "climb" to the crown of big trees, and most of them grow under trees; In addition, there are few epiphytes on the tree.

Botanists have found that most of the trees in the forest are Lauraceae plants, such as Cinnamomum camphora, Cinnamomum cassia, FAGACEAE plants, such as Quercus, Cyclobalanopsis glauca, Cyclobalanopsis glauca (beech) and so on. There are many camellia and Magnoliaceae plants. Their leaves are very big, especially at the top of camellia, which are bright and shiny (just like Lauraceae and Fagaceae plants). There is a thick layer of wax on the leaves, which can reflect sunlight.

In addition, there are many gymnosperms, such as pine and fir, which is also one of the important characteristics of light-leaved forest. The most famous gymnosperms are sequoia, torreya grandis and Chinese fir in North America. Their leaves are flat and smooth. Needles are arranged on branches like pinnate fronds of angiosperms. The branches are perpendicular to the light. There is also a gymnosperm with scaly needles. The whole branch is like a long leaf, perpendicular to the light, like North American cedar and heterophyllous cedar produced in North America.

Zhao Yelin of China ranks first in the world.

China's shining leaf forest is distributed in the south of the Yangtze River (it can surpass the Yangtze River in some places), including East China and Central South China.

Fagaceae plants are the most in this area, followed by Lauraceae and Magnoliaceae plants, and gymnosperms are more. In addition to the above tree species, there are plants such as Ericaceae, Rubiaceae, Ilex, Euphorbiaceae, Myrtaceae, and wild peony.

Among these woodlands, the characteristics of subtropical forests are very obvious. There are many ferns under the forest. For example, Pteris vittata grows in patches under the Pinus massoniana forest in Hunan, and there are many bamboos in some places.

The light-leafed forest in China is very similar to that in southern Japan.

There are many FAGACEAE plants in America, such as Quercus, Beech, Magnolia and many gymnosperms. Among them, sequoia and giant sequoia are the most famous tree species in the world.

Giant sequoia is called "the Lord of the world". Sequoia is the thickest redwood tree with a diameter of 4 meters. It is feasible to make a hole in the trunk. Sequoia is relict plant, known as the living fossil. In the past, it was widely distributed. Later, most of them were destroyed by glaciers, and now they only exist in California, not far from the coast.

Magnolia grandiflora (also known as Magnolia grandiflora) is planted in many cities in southern China. Magnolia grandiflora is a plant of Magnoliaceae, evergreen, with oval leaves, thick skin and luster. Magnolia grandiflora in China was introduced from the United States.

Magnolia grandiflora and Magnolia grandiflora in China belong to discontinuous families and genera (some species are distributed in Asia and some species are distributed in America), separated by the Pacific Ocean. Why is this happening? Some scholars have analyzed that the place where Asia and America used to connect is in today's Bering Strait, and Asian species may be distributed to America through this place (later land); Later, because the strait changed from land to sea, American species separated from Asian species and new species developed independently. Although the forms are different, they are related.

For another example, there are two species of Liriodendron in Magnoliaceae, one is in East Asia, and the other is similar, but its leaves are different from flowers. This is also a typical example of the discontinuous distribution of two species in this genus. Scientists hybridized the two species, bred a new species and successfully introduced it to China.

Africa and Oceania also have shiny foliage forests.

Light forests in Africa are mainly distributed in Canary Islands and Madeira Islands. Although the forest area is small, the typical tree species are laurel and avocado. There are many undergrowth shrubs, many kinds of undergrowth shrubs and leathery leaves. In addition, there are lianas and mosses.

The shining foliage forest in Oceania is quite special.

Australia has a unique eucalyptus forest in the world, with hundreds of species. Among them, the tallest eucalyptus is as high as140m, much higher than the giant Chinese fir. It is planted in North America. The former is called Liriodendron, and the latter is called Liriodendron North America.

Eucalyptus leaves are hard, and most of the growth direction is not facing the sun, but almost parallel to the light. This is because the angle between leaves and light is not right angle, which can reduce the chance of being burned by strong sunlight.

In addition to eucalyptus, there are many ferns in Australia's light forest, such as tree ferns. There are also many acacia trees in Leguminosae. In addition, there are rare woody compositae plants.

In New Zealand, there are many conifers and cypresses in the light-leaved forest, the most famous of which is Podocarpus. The leaves of conifers and cypresses are wide, and there are many angiosperms and dicotyledons. There are hundreds of dicotyledons, all of which are leathery, smooth and oval, and there are many woody ferns under the forest.

The Mediterranean is a strange place.

There are many kinds of subtropical plants. The Mediterranean region of Europe and Africa is very special. Its climate is dry in summer and rainy in winter. It is called the subtropical climate in dry summer. The annual precipitation is 400-600 mm, concentrated in winter, and it hardly rains in summer. The average temperature in the hottest month is 22 ~ 28℃ in summer and 5 ~ 12℃ in winter. There is plenty of sunshine, even in rainy winter, there are many sunny days. This is a typical Mediterranean climate.

In this typical Mediterranean climate, typical Mediterranean plants have been formed. For example, the olives we are familiar with come from the Mediterranean region. Because the Mediterranean climate zone is consistent with the distribution area of olive growth, it is also called "olive oil climate".

Because of the dry climate, the trees here are neither dense nor tall; There are neither epiphytes nor vines, and there are many evergreen shrubs under the forest, which grow densely. In addition, there are many perennial herbs, most of which are bulbs, bulbs and rhizomes, which are the result of adapting to the arid climate. Because winter is warm, the plants here generally don't shed their leaves, but the leaves become hard and thick. The leaves of plants in these areas are completely dark gray. The stomata under the leaves are all immersed in the leaves to avoid excessive transpiration of water, so even in the dry season, plants will not lose their leaves. This phenomenon is completely different from the characteristics of leaf forest.

There are many special phenomena in plants in this area: the leaves of some plants degenerate and become smaller; The stem is green and can be used for photosynthesis; Many trees have no bud scales because they are warm and rainy in winter (they don't need to rely on bud scales to keep out the cold); Many plants can secrete volatile oil and enclose themselves in oil vapor, thus reducing the evaporation of their own water. The ability of plants to resist drought is really wonderful.

Hardleaf plants in the Mediterranean

Due to the special climate in the Mediterranean region, there are many drought-tolerant plants distributed on the north and south coasts of the Mediterranean. The hardwood plant Quercus variabilis is distributed in Spain, Portugal, Morocco and Algeria in the western Mediterranean, and Quercus acutissima is distributed in Crete and Cyprus in the eastern Mediterranean.

There are also coniferous forests in the Mediterranean region, and there are many kinds of pine trees, such as pine, Aleppo pine and Lebanese cedar. The latter is one of the most famous garden plants in the world. In addition, there are many hard-leaved shrubs in the Mediterranean region, such as black hook leaf (Ericaceae) and oleander.

In southern France, there are many low shrubs, such as oak trees, whose height does not exceed 1-2 meters; There are many branches; The leaves are hard and have irregular thorns on the edges; A long part of the nut is exposed outside the shell, and there are thick hairs outside the shell; Known as the typical representative of hardwood plants.

In Spain, there are many kinds of lavender with narrow leaves and blue-purple flowers.

There are also many spiny shrubs growing in the Balkans, such as Aralia elata, a leguminous plant.

In addition, there are hard-leaved shrubs in some parts of America and Africa, especially the Cape of Good Hope in Africa, which is the origin of geranium.

The miracle of plants in arid desert

There are dry deserts in subtropical areas, where plants are very strange, mainly some super-xerophytic shrubs and semi-shrubs.

The desert area has a dry climate and little rainfall. The annual precipitation will not exceed 250 mm, mostly below 150 mm, or even only a few millimeters. The average temperature in the hottest month in summer is 40℃, and the highest temperature in the Sahara desert is 69 ~ 74℃.

There are many special plants in the desert of South Africa. At 23 degrees south latitude. Go north along the Atlantic coast. The trunk of this plant can reach 4 meters, the exposed part is only 20 centimeters, and there are two strip-shaped leaves, the length of which can reach 3 meters, and the life span of the leaves can reach 100 years.

There is a short-lived chrysanthemum in the Sahara desert. This plant is short and leafy. It is a herb with many corollas. When the climate is humid, the fruit of this plant can germinate quickly, grow into plants, blossom and bear fruit, and its life cycle generally does not exceed one month. When the drought comes, it will bear new fruits and fall to the ground, waiting for the rainy season.

In the oasis in the desert of Africa, there is a kind of plant called date palm, whose fruit is edible.

In the desert of the United States, there are many succulents such as cactus, fairy whip and agave.

Australia has a salty desert where acacia, Casuarina and eucalyptus grow. Casuarina is a tree with green branches and no leaves. In fact, its leaves are as small as scales, so it is called a "branch tree". Casuarina equisetifolia was introduced to the southern coast of Guangdong Province to prevent wind. There is also evergreen, which belongs to Liliaceae and has a strange shape. Its trunk is about 2 ~ 3 meters high, and the trunk is covered with dense grass-like slender leaves, which is called "grass tree".

In the Arabian desert, there are tumbleweeds. This plant has many branches. Flowers bloom under the branches and leaves. The whole plant can be gathered together. When the wind blows, the whole plant is uprooted, rolled with the wind, and rolled down the fruit to achieve the purpose of spreading the fruit.

Subtropical sandalwood is closely related to human beings.

There are many economic plants in subtropical areas, including fruit trees, timber plants, vegetable plants, oil plants, flower plants, etc., which are very rich and closely related to human beings.

It is particularly worth mentioning that Taxus chinensis is a rare plant with beautiful seeds and flowers. Its seeds can be used as medicine, and its wood is of great use, which is one of the precious plant resources in China. It is reported that an 800-year-old yew tree in Ruyuan Yao Autonomous County of Guangdong Province was illegally cut down by criminals. There are more than 654.38+ten thousand yew plants in the local area.