Speaking of the stems of plants, people will naturally think of the trunks of big trees (woody plants), wheat stalks (herbaceous plants), and the twining vines of lianas; in fact. In the colorful nature, some plant stems are not what people usually see, but are all kinds of strange and interesting.

The "waist" of plants

As the saying goes, a healthy person has a strong waist. That is to say, a healthy person's waist is straight and not hunched over. In fact, plants are just like people; trees that grow normally have straight and tall stems; branches that grow crookedly are probably not healthy trees. therefore. It is not an exaggeration to call the stem the "backbone" of a plant.

The tallest tree in the world is the North American redwood, which can reach a height of over 100 meters and a trunk diameter of more than 10 meters. Its tallness and majesty are due to the stems playing a decisive role. The Wangtian tree in Xishuangbanna, my country, is a broad-leaved tree with a trunk as high as 40 meters.

Because you have to look up to look at its treetops, it's like looking at the sky, so people call it the sky-looking tree.

Sunflower is an annual herbaceous plant, which can reach a height of more than 3 meters. The stem is very thick, and there is a large flower disk (flower head) like a basin on the top. If there is no strong stem, it will be in any case. It cannot support such a large flower pot.

Even those herbaceous plants that grow very small have straight stems. Although the small stems look unusually slender, they are upright and not bent. For example, shepherd's purse growing on the grass in spring has flowers blooming up and down on the upper part of the stem. Moreover, while blooming, the stem also grows upward, constantly growing new flowers.

Water ranunculus is a plant that grows in water. Although its stems and leaves are not hard and grow completely underwater, when it is about to bloom, it will produce straight flower stems to lift the flowers out of the water, making it easier for insects to pollinate them.

Whether they are tall and strong, or short and slender, the stems of plants have the same function, which is to support the body and expand the space as much as possible. There are branches on the main trunk of the plant, and small branches grow on the branches. The small branches grow leaves, which can be expanded to receive the nourishment of sunlight, perform photosynthesis, and produce nutrients for their own survival.

The reason why plants can withstand the test of wind and rain largely lies in the structure of the stem: the stem of the plant has a very supportive mechanical tissue (composed of thick-walled cells).

The "transportation line" of plants

In addition to supporting the body, the stems of plants also have a very important function - transporting water and nutrients.

The water needed for plant growth and the inorganic salts in the water are all in the soil. Through the roots, plants can absorb these water and inorganic salts, but to transport them to the branches and leaves, they must pass through the stems.

The roots of plants have root pressure, which allows water to move upward; the leaves produce the ability to absorb water through photosynthesis, allowing water in the roots to continuously rise. The path of ascent is in the stem. There are vascular bundles in the stems of plants, and there is a kind of conduit (composed of conduit molecules) like a tap pipe, which allows water to pass through and be transported up to the branches and leaves to prepare for the needs of photosynthesis. Another type of tube in the vascular bundle is composed of sieve tube molecules, which are specially used to transport nutrients produced by the leaves down to the roots to meet the growth needs of various parts of the plant.

All kinds of stems

Due to the complex external environment in which plants grow, the shapes of plant stems are also strange, and they are not necessarily straight and tall.

As we all know, plant leaves are produced from buds on stems and branches. The place where sprouts sprout is the node on the stem. After the trees fall off their leaves, you can see the buds where the petioles fell off. When the buds sprout the next year, they can produce a twig. Leaves will grow on the twigs, and there will be buds in the leaf axils. If they are renewed in this way, they will grow every year. New leaves and buds appear every year, and life continues. If the "branches" we see have no buds on them, they may not be stems, but roots, because leaves do not grow on the roots of plants.

In this way, we understand that "there are nodes on the stems, leaves at the nodes, and buds in the leaf axils."

Leaf-like stem

The stem of the artificial leaf tree resembles a leaf, oval and flat. Its shape is almost the same as that of common plant leaves, but in fact, this It's the stem of the artificial tree.

The "leaves" of the pseudoleaf tree are formed by the flattening of stems and branches, which botanists call leaf-shaped branches (branches metamorphose into leaf shapes). The leaf-like branches are oval in shape and relatively hard in texture. This stem of the rhododendron is the result of adapting to a dry environment. Flattened branches contain chlorophyll, which can replace leaves for photosynthesis to produce nutrients. The real leaves are reduced to very small scales, which are almost invisible if you don't look carefully. This degraded leaf loses chlorophyll because it is not needed for photosynthesis.

The degradation of leaves can reduce water transpiration and help resist drought conditions, while the flattening of stems and branches can allow photosynthesis without losing the ability to produce nutrients.

Rosewood belongs to the genus Rosewood of the Liliaceae family. It is a semi-shrublike plant that grows in arid areas of the Mediterranean. The flowers of artificial leaves are unisexual and dioecious.

Some readers may ask: Why do botanists believe that the leaves of artificial leaf trees are stems and not leaves? In fact, just observe the growth position of the flowers and fruits of artificial leaf trees. Everything is understood. The flowers and fruits of the artificial leaf tree all grow in the center of the leaf-like branches, that is, the midrib, which proves that the central part is the branch itself (because the flowers and fruits of the plant grow on the branches, not the leaves), and the flat objects on both sides It is the flattened part of the branch.

The artificial leaf tree not only has interesting artificial leaves, but also has beautiful red fruits, which are of great ornamental value. my country has long introduced it as a bonsai. Reproduction can be carried out by branching.

Potato itself is a stem

The potato we often eat is itself a stem. In botanical terms, this altered stem is called a "tuber."

Some people may ask, how can a potato be a stem? If you observe carefully, you will find that there are some small depressions on the surface of the potato. These depressions are called "bud eyes". There are buds inside. If you plant potatoes in the soil, the buds in the depressions of the potatoes will sprout and grow branches and leaves.

Generally, the stems of plants have nodes, and there are leaves on the nodes. Buds sprout in the leaf axils (the junction of leaves and stems), and the buds can give birth to branches and leaves.

So, where are the knots of potatoes? There is a mark on the edge of the potato depression, and there is a thin irregular piece on the mark. In fact, the depressions in the potato are the nodes from which the sprouts grow. Then branches and leaves grow. Potato nodes used to have leaves, but the leaves have metamorphosed and degenerated into residual thin slices without chlorophyll. From this point of view, potatoes completely conform to the characteristics of stems.

Potato is a kind of abnormal stem, and its expansion plays a role in storing nutrients.

Potatoes contain a variety of nutrients and are rich in vitamins, especially vitamin C. Vitamin C can fight scurvy. Sailors on ancient voyages often brought potatoes to eat during the journey to prevent scurvy. In addition, potatoes also contain protein, phosphorus, iron, inorganic salts, etc.

Potatoes belong to the Solanaceae family and are native to the Andes Mountains of South America. They were introduced to Europe in the 16th century and became the main food source for Europeans. Potatoes were first cultivated in my country in the late Ming Dynasty. They were first cultivated in North China and then gradually spread throughout the country.

Root-like stem

The stem of a plant is generally slender and cylindrical, growing on the ground; if it grows in the soil. It is often mistaken for the roots of plants. But there are indeed some plants whose stems grow in the soil and are thin and long, just like roots. In botany, this underground stem is called a rhizome or rhizome.

Many herbaceous plants have rhizomes, such as Polygonatum odorifera. Its rhizomes are white and have nodes and internodes like bamboo (the part between the two nodes is called an internode). Completely consistent with the characteristics of the stem. The underground part of another plant, Aesculus aesculata, is also mainly a rhizome.

The rhizomes of the two plants mentioned above have many thin whiskers, which are their real roots.

In addition, the underground part of bamboo called bamboo whip is also a rhizome. There are buds on the bamboo whip, which can grow bamboo.

Ball-like stems

The ends of the underground stems of some plants become enlarged and appear in the shape of regular balls, ovoids or oblate balls. This globular shape is formed from the metamorphosis of the top of an underground stem and is often called a "bulb."

Careful people will find that bulbs have many characteristics of stems: the bulbs have obvious nodes and internodes, and there are film-shaped scales and a few buds on the nodes.

The function of the ball is to store nutrients so that plants can survive the winter.

The more typical bulbous plants are Sagittarius and Water chestnut. The former belongs to the genus Sagittarius of the family Alismataceae and the latter belongs to the genus Sagittarius of the Cyperaceae family. They are both aquatic plants and their bulbs are edible.

Lily is a very interesting plant. Its underground part is a white or light brown ball. This ball is not the root of the lily, but its stem, which is called a "bulb" in botanical terms.

There are many white thick scales on the lily bulbs. If you peel off these scales one by one, you will find a cone-shaped thing in the center of the bulb, and all the scales grow on it. In fact, the cone-shaped thing is the stem of the lily, and the scales are the leaves of the lily. The abnormal leaves grow on the abnormal stems, forming the unique bulb of the lily.

Lily belongs to the genus Lilium of the Liliaceae family. There are 80 species in the genus. They all have bulbs, but the bulbs of different species vary in size and color. Bulbs not only have scale leaves, but also buds. Lilies can be reproduced from bulbs.

In addition to lilies, plants of the genus Allium, such as onions, garlic, scallions, etc., all have bulbs. Some flowers, such as daffodils and tulips, also have bulbs.

Bulbs play an important role in plants. Lilies and mountain dandelions often grow in places with shallow soil on cliffs. Because they can store nutrients and water through their bulbs, the plants can grow in places with less than ideal water and nutrient conditions. What’s even more amazing is that even if the flower branches on the ground are damaged, as long as the underground bulbs are intact, they can still grow new branches, leaves and flowers. It can be seen that the bulb is the reproductive organ of mountain dandelion.

Compared with the bulbs of lilies, the bulbs of arrowheads and water chestnuts do not have such thick scale leaves, and the leaves are relatively thin. But both bulbs and corms can be used for reproduction. In this regard, the two have the same purpose.

Spine-like stems

The trunk of the honey locust tree has many hard thorns, and there are branches on the thorns. In fact, these hard thorns on the honey locust tree are a branch with the same properties as the stem. It is a metamorphosis of the stem.

The thorns of the honey locust tree are very sharp and have a certain protective effect on the trees.

The honey locust tree belongs to the Fabaceae family. It is a large deciduous tree with pinnate compound leaves, yellow-white flowers, and fleshy fruits that can reach 30 cm in length. The honey locust tree can be found almost all over the country. The decoction of its fruit can be used as soap; the hard thorns can be used as medicine and have the effect of activating blood circulation and reducing swelling, so they are called "soap locust thorns". People often cut the hard thorns on the saponins in autumn, cut them into slices, and dry them in the sun for later use.

It should be noted that not all thorns on plants are branch thorns, that is, abnormal stems. For example, there are thorns on the branches of roses, roses, and roses, but these thorns are skin thorns, which are formed from the epidermal cells of the stems and branches, and are not branches. This is very different from the honey locust tree. The thorns are relatively small and can be easily removed by hand, but the hard thorns on the honey locust tree are not easy to remove.

The thorns of Ulmus elata (belonging to Ulmaceae), citrus fruit trees (belonging to Rutaceae) and buckthorn (belonging to Rhamnaceae) are very hard and are branch thorns. The thorns of black locust (belonging to the Fabaceae), jujube, and wild jujube are metamorphosed leaf thorns, formed from the metamorphosis of stipules.

Stems and our lives

For humans, plant stems are of great use.

Trees are building materials. There are pillars in the architecture of the Ming Tombs in Beijing that are made of single tree trunks. They are nanmu from the Lauraceae family. This kind of wood is hard, antiseptic and insect-proof, and can last for thousands of years.

In the past, railroad ties were also made from tree stems.

Bamboo is also a commonly used building material, such as the Dai Bamboo House in Xishuangbanna. Beautiful and chic.

The stems of some trees can also provide food for humans, such as the sago palm tree in the palm family. Its trunk is rich in starch. If you peel off the main trunk and remove the starch, you can make "sago rice". "Sago rice" is white and crystal clear, like high-quality rice, has a unique flavor and is edible. Therefore, the local people call the sago coconut tree "rice tree".

A large part of the white sugar we often eat comes from the stems of sugar cane. The stems of Canadian sugar maples are rich in sugar, which can be refined into maple syrup.

The stems of some plants are rich in strong fibers and can be used to weave cloth or make ropes. For example, ramie fiber can be used to make linen, and hemp and jute fibers can be used to make sacks and ropes.

The stems of some plants are also used as medicinal materials. Motherwort can grow to more than one meter high, and the whole plant can be used as medicine, among which the stems of motherwort account for a large proportion. The tuber of Gastrodia elata is an important medicine for calming spasm and dispelling wind, and can cure dizziness and headache.

Polygonatum from the Liliaceae family grows in the soil and can be used as food or processed into medicinal materials. It has a nourishing effect similar to that of ginseng. The bark of the cinchona tree contains quinine, and the bark of Eucommia ulmoides can treat high blood pressure.

Some plants in the desert, such as cactus stems, are rich in water and can be used by travelers to replenish water. The trunks of poplar trees are also rich in water, and water can be obtained by drilling holes.

In addition, there is a kind of vine in the tropical forest. The vine stores water like a tap pipe and can be cut open to drink the water directly.

The bark of some plant stems is also useful. The cork oak tree produced in Europe has a thick cork layer that can be cut off to make cork and shoe soles.

There is a particularly tall chestnut tree in Sicily, Italy, with a hollow trunk. The local people use it as a storage room.

Expensive furniture is mostly made from the trunks of leguminous plants, such as rosewood, rosewood, and rosewood.

In addition, the trunks of lacquer trees contain lacquer, the trunks of pine trees contain rosin, the trunks of rubber trees contain rubber, and the stems of reeds can be used to make paper, etc.