Parade in forty-one analysis. Yulia Vladimirovna Drunina

Typical symptoms of bacteriosis are dwarfism, discoloration, wilting, rot and the formation of cancerous growths.

Fungi and bacteria

Typical symptoms of bacteriosis are dwarfism, discoloration, wilting, rot and the formation of cancerous growths. Typical example diseases of this type - cancer of the roots and root collar in many plants, caused by Pseudomonas tumefaciens Sm. With. T. During their life, these bacteria secrete substances that stimulate increased growth and division. plant cells, which leads to the formation of tumors, swellings, thickenings on trunks and stems, which after some time rot and collapse.

A clear example of such an effect is the formation of so-called witches’ brooms in the crowns of trees (alder, poplar, maple, elm, oak, birch) when infected with fungi from the family Taphrinaceae. The fungal secretions cause the axillary buds to actively grow, which leads to the formation of dense clusters of short and thin shoots, often branched. Such shoots almost never bear fruit, the leaves on them are small, irregular shape, quickly falling.

Gray-yellow tinder fungus
mistletoe
Large rattle

From the floral department

During the flowering period, they usually form a spike-shaped inflorescence, where great amount small, dust-like seeds capable of long time maintain germination. The seeds are carried by the wind over considerable distances and germinate only on the roots of suitable host plants under the influence of root exudates and at a certain acidity of the soil.

To combat dodder, strict plant quarantine, thorough cleaning of the seeds, mowing of affected forage grasses and stubble burning, spraying with various chemicals (lime-sulfur decoctions, solutions of ferrous sulfate and ammonium nitrate), etc. are used.

Broomrapes grow on the root systems of deciduous trees, most often birch.

Mistletoe forms dense, spherical bushes with numerous branched shoots and thick, oblong-oval green leaves. Capable of photosynthesis, but cannot exist independently, since it is completely torn off from the soil and feeds on the juices of the host plant with the help of haustoria and root-like rhizoids spreading under the bark. The seeds are covered with viscin (a very sticky mucus) and are easily transferred to neighboring trees, sticking to the legs and feathers of birds.

There are parasites not only in the animal world but also in the plant world. They do not form, like ordinary plants, organic matter from air, water and soil. Settling on the stems or roots of the “host” plant, the parasites feed on their juices. These slackers are almost always easy to distinguish: their shoots do not contain chlorophyll, and therefore not green. Photosynthesis, which requires chlorophyll, is not needed by parasites for the life process. They also do not have their own roots, since they themselves are “too lazy” to pump water from the soil, preferring to take it from the tissues of the “host”. So what is it - parasitic plants?
Parasitic plants– these are plants that live entirely or partially from the nutrients of living organisms. Parasitic plants exists both among lower and higher plants, including flowering plants. Fungi, algae and bacteria parasitize plants, animals, and humans, often causing infectious diseases. Flowering parasitic plants parasitize mainly on higher plants, including cultivated plants (sunflower, tomatoes, tobacco, etc.), reducing their yield. Optional parasitic plants can exist both due to alien eating (parasitism) and using other methods of nutrition (for example, photoautotrophic). Other food sources are sometimes used and obligate parasitic plants (semi-parasitic plantsare both alien-eating and phototrophic organisms; Petrov's cross is both a parasitic plant and a predator plant). Parasitic plants or are introduced into the tissues of the host organism onlyhaustoria , serving to extract food (ectoparasites, for example powdery mildew, from flower parasites - broomrape) or develop completely or mainly in the tissues of the host plant and come to the surface of its body only for reproduction (endoparasites - Rafflesiaceae).
Let's now take a closer look at some of the parasitic plants.
DODDER - gave its name to the dodder family. It is devoid of roots, but has only a long stem and scaled leaves. Its very name says that it wraps around the host plant. There are many types of dodder, and they parasitize various plants, mostly herbaceous: both wild and cultivated. Clover, alfalfa, flax and hops are especially affected by dodder. In the spring, the dodder seedling is fixed into the soil with its lower end, and the upper end, making circular movements above the surface of the earth, finds a suitable plant and twines around it. This parasite is attached to the victim by suckers called haustoria, which quickly grow from the stem. Penetrating deep into the tissues of the host plant, haustoria begin to suck out nutrients. The original root quickly dies off as unnecessary. Dodder has neither roots nor green leaves. On its shoots, only numerous pale pink flowers collected in balls develop.
All types of dodder found in our latitudes are annual plants. In autumn, their shoots die off. New plants grow on next year from seeds. Seeds that fall to the ground and lie there over the winter germinate at the end of spring, when other plants have already more or less developed, otherwise there would be no suitable food for the parasite.
The dodder seedling is unlike the seedlings of other plants: its thread-like body does not have cotyledons, the lower end of the seedling does not grow into the soil, only its upper end grows. If a dodder seedling encounters a suitable host plant, it quickly wraps around it, forms suckers, and continues to grow. If the parasite seedling does not meet the host plant, it dies, since it cannot feed on its own. Dodders cause great harm to agriculture, and they are stubbornly fought against. For example, hay infected with dodder dries poorly and often becomes moldy. It cannot be destroyed by tearing it into two parts. Instead of one plant, two appear. Therefore, to combat it, you cannot simply weed the garden. Thus, seeds of cultivated plants intended for sowing are cleaned of dodder seeds by treating them with chemicals.

Tree rings, annual layers, in plants these are growth zones wood , caused by the seasonal periodicity of cambium activity as a result of the change in warm and cold seasons. They are clearly visible in cross sections of the trunk, branches and roots of woody plants in the form of not quite regular (not strictly concentric) rings.
Thanks to the division of cambium cells, the stems of trees, shrubs and perennial grasses grow in width. There are centuries-old oak trees whose trunks reach 10 meters in girth. The stem grows in thickness during the warm season, when the cambium cells divide. When cambium cells divide, much more wood cells are formed than phloem cells. By the end of autumn, the cambium enters a dormant period. In the spring, with the beginning of sap flow, cambium cells begin to divide again. From the cells that emerge from the cambium in the spring, vessels with wide openings and relatively narrow membranes are formed in the wood. In autumn, in most trees, new wood vessels turn out to be narrow-lumen, and their shells are thicker. All layers of wood cells formed in spring, summer and autumn make up annual growth ring.
The small autumn cells are different from the large spring wood cells of the following year that are next to them. Wood deposited by the cambium in spring or early summer differs in structure, color, shine, hardness and other mechanical properties from wood formed in the second half of the growing season. First (inner) part tree rings
etc.................

A huge number of seeds ripen in the fleshy fruits of rafflesia. A layer or other large animal passing through the jungle steps on these fruits, crushes them, and the seeds stick to its feet. If an animal steps on a cissus root again anywhere, the rafflesia seeds will stick to the root and sprout. The sprout from the seed will make a hole in the bark of the host plant and give rise to cellular cords that will develop between the living cissus cells (in the intercellular spaces) and suck nutrients from them.

Rafflesia Arnoldi is found only in Sumatra. Other types of Rafflesia, with smaller flowers, are found in Java and other islands of the Malay Archipelago. The amazing rafflesia flower is unusual even for the local population and gives rise to superstitions. On the island of Java, until recently, it was considered sacred and worshiped.

Broomrapes reproduce by seeds that germinate on the soil surface. The filamentous seedling does not have the usual cotyledons; neither the stem nor the root can be distinguished on it: it all consists of identical tender cells.

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IN southern regions In our country, the mistletoe plant, a strongly branching perennial shrub, very often settles on the branches of poplars and fruit trees. This plant, thanks to its leaves, is still capable of photosynthesis, but it takes water and minerals from the trees with the help of suckers that penetrate the wood of the host plant.

Particularly destructive to plants are colorless alien-eaters, which completely lack chlorophyll.

These “freeloaders” exist entirely at the expense of the plant on which they settle. These, for example, include Peter's cross. Its fleshy, colorless stems with a one-sided cluster of crimson-red flowers appear in our forests only in early spring. If you dig up the ground around the plant, you can see how its underground part intricately branches, forming characteristic cross-shaped intersections, from which the name of the plant comes.

Broomrape also matches it, fully justifying its name, because, like an infectious disease, it destroys sunflower and hemp crops, sucking the juices from their roots.

mistletoe

The stems of the plant are usually as thick as a pencil, but the largest mistletoes have trunks 5 cm thick. Mistletoe sometimes lives up to 40 years.

Nature has “thought out” well the way mistletoe spreads. Mistletoe produces sticky berries in September white(for which it received its name). In ancient times, these berries were used to make glue for catching small birds, which is why white mistletoe received another name - “bird glue.” Mistletoe berries are inedible for humans, but birds, especially blackbirds, are big hunters of them. In the stomach of the bird, the seeds make their journey to new “places of residence.” Now a lot for them depends on “luck”. If they fall to the ground along with bird droppings, they will die. And if they find themselves on a tree branch, they will stick to it with the remains of undigested sticky pulp. In the spring, the seeds will begin to germinate: they will release a root that will pierce the bark and grow into the branch of the host plant. The mistletoe root can easily cope with the bark of young branches, but it can also “gnaw through” the bark of 60-year-old branches, using organic acids. Mistletoe never develops real roots; they are replaced by sucker roots that draw life-giving moisture from the host plant. In its second year, the mistletoe will grow leaves.

"Living transport" that uses mistletoe for dispersal has its drawbacks. Digestion in birds is very fast - the berries are completely digested in less than half an hour. Australian biologist V. Serventi explained by this that there is no mistletoe on the island of Tasmania, although it is very common in Australia. From Australia to Tasmania it is more than an hour's flight, and the seeds do not have time to reach their destination, falling into the sea.

Peter's cross

True, for ten months of the year the plant is hidden underground, where its rhizomes receive nutrients. For this, Peter's cross was also called a hidden place. Here no one tears it, tramples it, and herbivores do not eat it.

Broomrape

Broomrape can be seen on sunflower, hemp, tobacco, clover crops, and among garden crops. It is easily distinguished by the pale brown color of the stem and scaly leaves. These leaves are never green: they have no chlorophyll. Numerous rather large flowers, most often bluish-purple, sit on the upper part of the stem. A significant part of broomrape is found in the soil. With its expanded base, its stem grows to the roots of the host plant.
Broomrapes reproduce by seeds that germinate on the soil surface. The filamentous seedling does not have the usual cotyledons; neither the stem nor the root can be distinguished on it: it all consists of identical tender cells,

At one end of the sprout string, the seed coat remains in the form of a cap. This end can be considered the top of the stem. Its opposite end grows into the soil so that the tip of the seedling describes a helix. The broomrape seedling stops growing as soon as its tip touches the root of the host plant. The seedling attaches itself tightly to this root and begins to thicken. Wart-like growths appear on the surface of the thickening. The rest of the seedling, bearing the “cap,” dies. The warty body releases a papilla, which grows into the root tissue of the host plant and begins to suck nutrients from it.

Dodder

Dodder (Cuscuta) is a climbing plant. When dodder seeds germinate, the tip of the root bends and is partially immersed in the soil. The filamentous spiral sprout is elongated, and its tip produces rotational movements. The direction of movement is adjustable chemicals secreted by the host plant. The root end then dries up and the stem twines around the host plant. With the help of suckers, the dodder attaches to the stem and receives all the necessary nutrients from the host plant. Dodder often leads to the death of crops. It causes particular harm to clover crops.

Abstract on the topic:

Plan:

1Classification
2Some representatives

2.1Rafflesiaceae
2.2 Santal
2.3 Broomrapaceae

Notes

Introduction

1. Classification

2.2. Santal

In the southern regions of Russia, quite often the mistletoe plant, a strongly branching perennial shrub, settles on the branches of poplars and other trees. This plant is capable of photosynthesis, but it obtains water and other minerals through the haustorium, which penetrates the xylem of the host tree.

2.3. Broomrapaceae

Representatives of the Broomaceae family lack chlorophyll and subsist entirely on the host plant on which they grow. Representatives of the Peter the Cross family are widely known. Its fleshy, colorless stems with a one-sided cluster of crimson-red flowers appear in Russian forests in early spring. The root located in the soil branches and forms cross-shaped joints, from which the name of the plant comes.

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The embryo grows for nine long months until it becomes a flower, and flowering Rafflesia lasts several days. It is not clear how such a plant “survived” to this day! IN last years Rafflesia numbers have been greatly reduced. Biologists are sounding the alarm - the tropical forests of Borneo and Sumatra are being brutally destroyed.

Rare Rafflesia flower spread by spores carried by wind and insects. The flower, called "mahkota" by the indigenous tribes of Malaysia and Indonesia, requires a lot of water to grow and bloom.
Flies mainly pollinate flowers. Attracted by the eerie smell Rafflesia they carry spores on themselves from one inflorescence to another. The aroma, if you can call it that, of this flower is simply disgusting. Rafflesia smells like rotten meat, causing dozens of flies from the surrounding area to flock to it. Due to the flower's nine-month growing period, Rafflesia is considered a flower of fertility and abundance by the Aboriginal tribes of Africa.

Rafflesia, due to its smell, received the name " Corpse Flower». Most of These plants grow in the forests of Sumatra and Borneo, as well as in the Indonesian archipelago. Slightly different, but similar, plant species grow in the jungle South-East Asia and on Philippines. The largest representative of Rafflesia (1.04 meters and 12 kilograms) was recorded in Malaysia.

It is not known how long these flowers will live. Some ecologists propose to recreate the environment Rafflesia artificial environment. But so far, all attempts to grow the “Corpse Flower” in greenhouse conditions have not been successful. One thing is clear - it is necessary to save the forests of Borneo and Sumatra from deforestation and fire.

There are indications that plants of this group can be content with humus. True parasites are plants that lack the green color (chlorophyll) and therefore have lost the ability to prepare organic substances necessary for life from air, soil and water. They receive these organic substances in ready-made form. However, it is necessary to mention here that there are many achlorophyll-free plants that feed on dead organisms or their waste. These plants are commonly called saprophytes. Some saprophytes with favorable conditions can feed on the juices of living organisms and in this case become real parasites (for example, honey fungus, cholera bacterium). Thus, here too between real saprophytes and real parasites we have whole line transitional forms. In relation to host choice, different parasites behave differently. While some can settle on very diverse organisms, others are capable of developing only on strictly defined species. Parasites can actually be divided into lower (bacteria and fungi) and higher (seed plants). They further distinguish: ectoparasites, which penetrate the host with only one part of their body, for example, mistletoe, dodder, head scab fungus, etc., and entoparasites, which live entirely inside the host - poronosporous fungi (see XVII, 102) and bacteria of infectious diseases. Bacteria parasitize mainly in animals and, once in the blood, multiply due to the abundance of nutrients with amazing speed, unless they encounter counteraction in the white blood cells or in the antitoxins of the blood serum (see bacteria). Infection of the fungus by parasites occurs through spores, which are deposited on the surface of the host’s body, grow into long threads (hyphae) and penetrate inside through various pores. Only thick layers of skin, strong bark with a cork, or dead dry crust can resist attack by parasites, and even then not always. The parasite often dissolves cell walls with the help of special enzymes and gradually penetrates inside. Having reached living cells, the hyphae penetrate the walls and release club-shaped swollen suckers, haustoria, into the middle of the cell, with which they then suck out the necessary substances, decomposing and dissolving the contents of the host cells. It is, of course, difficult to say which substances are absorbed in this way, although there are some indications. So, for example, tannins are absorbed from oak cells, and turpentine oil remains in pine cells. An attack by parasites rarely results in the death of the entire host plant; more often only certain parts are affected, for example, Famous places leaves or whole leaves, fruits. Infection occurs very slowly, and trees, for example, can live for many years after the onset of infection, and sometimes the affected parts, such as dead branches, are broken off by wind and birds. Attacks on animals are more vigorous, and some fungi cause, for example, enormous devastation among insects. Thus, Empusa Muscae is the cause of a widespread pestilence of flies in late summer and autumn. Just as is observed in the animal kingdom, the development cycle of a parasitic fungus sometimes occurs not on one host, but on several; example: bread rust (see mushrooms, XVII, 106). It is not uncommon for several parasites to adapt to the same host. Parasites are rare on mosses and liverworts. Aquatic plants are also relatively rarely affected by parasites; Most often, microscopic species of chytrid and saprolegnia fungi are found on them. Sometimes parasites are in turn attacked by parasites; for example, in Chile, Loranthus buxifolius is parasitized by L. tetrandrus. Among higher parasites, several groups are distinguished. Climbing parasites include species of dodder (Cuscuta) and cassita (Cassytha). The seeds of these plants germinate in the ground; then their thread-like stem, with the help of circular movements, comes into contact with the host plant, wraps around it and forms suckers, with which it penetrates into the host’s tissue and sucks out organic substances from it. Cassytha species live on the islands of the Malay Archipelago, are very similar in appearance to dodder, but belong to the laurel family. Dodder species (up to 60) are distributed everywhere. Of these, the most common are C. trifolii, which causes great harm to clover, and C. europaea, which parasitizes hops and nettles. Another group of parasites are perennial plants that parasitize the roots of trees and shrubs and develop numerous underground shoots, densely covered with scales. Every year, stems rise up from them, bloom, bear fruits and mature seeds, and die when ripe. Most known species— Peter's cross, Lathraea squamaria, forms a powerful rhizome weighing up to 5 kg. Its underground roots and shoots are completely white; above-ground flowers and bracts are purple-red in color. The seeds of this group are clearly divided into roots, cotyledons and stem primordia. In the third series of parasites—species of the family Balanophoraceae and Broomrapaceae—the seed encloses a shapeless embryo without cotyledons and a root and germinates on the ground. The thread-like seedling penetrates the soil, attaches to the roots of the host, penetrates into it and grows with it, forming a tuberous rhizome, from which a flowering stem later rises. In this group, fusion with the root of the host plant is so complete that it is difficult to determine where the tissue of the parasites ends and the tissue of the host begins. The most outstanding representative of the balanophorans is the genus Langsdorffia, the species of which live in tropical America, mainly in mountains up to 3000 m. The stems of Langsdorffia, as thick as a little finger, are branched, serpentinely curved, fleshy and club-shaped at the point of attachment to the host root. A germinating seed, falling on a suitable root, forms a ball and produces a very remarkable effect on the substrate. The root bark in this place is destroyed, its wood peels off, frays and is divided into fibers, the wood tufts rise towards the parasitic tuber and spread out in the form of a fan. Cells and vessels are embedded by parasites between wood fibers, intertwined and closely fused with them. The serpentine curved stems of Langsdorfia have the same effect when they fall on the root of a suitable plant. The fourth group is the Rafflesiaceae family. The seed also has an undivided embryo, during germination it penetrates under the bark of the host and forms between the bark and wood a hollow cylinder of rows of filaments, very similar to mycelium and often forming an extremely complex plexus with the cells of the host. The juices of the host pass into the tissues of the parasite, which grows quickly, breaks through the bark and forms stems with flowers, which in Rafflesia Arnoldi reach a huge size and are a meter across.