American cacti are different from other succulents. How do succulents differ from other succulents?

I dug up several plants and brought them to my home. Since the deep roots of the plants were damaged during digging, I decided to dry them a little so that the plants would not rot when planted, as happens with cacti. Imagine my surprise when a couple of days later I found my hodgepodges very wilted! Of course, Kushka, this is not Moscow. At the height of summer, daytime temperatures there are always above 35 degrees, relative air humidity during the day is always below 15%, and clouds appear in the sky not much more often than flying saucers. And yet! The cacti brought from cool Moscow were not going to dry out, even if during my field work they remained without watering for weeks, and the local saltworts, especially those from the Erlanduz depression, dried out. That time I didn’t understand anything, I dug up again and brought the saltworts to Kushka and again they withered very quickly. Only after this did I begin to understand that not every succulent plant is a succulent. Succulents are characterized not only by the accumulation of water, but also by their extremely economical use. Succulents have special type metabolism, allowing them to spend approximately 30 times less water per unit of assimilated substance than ordinary xerophytes. The CAM type of photosynthesis (CAM - Crassulacean Acid Metabolism) is that, due to the complication of the internal structure of the tissues of the assimilation organs, the process of photosynthesis occurs in two stages. The first stage - the absorption of carbon dioxide and its fixation - unlike ordinary plants, occurs in the dark with the help of phosphoenolpyruvate carboxylase with the formation of organic acids, which are stored in the vacuoles of the same cells. The second stage occurs during the day in the light, but with the stomata closed - carbon dioxide is released and included in the Calvin cycle - then photosynthesis proceeds according to the usual pattern. Thus, we see that the stomata of succulents open only at night, when the air temperature is minimal, the assimilation organs do not experience overheating, and the relative air humidity is at its maximum during the day. As a result, the loss of water vapor when the stomata are open is minimal. Of course, with strong solar overheating, succulents evaporate moisture during the day, but in any case, the intensity of daytime transpiration is 2-3 orders of magnitude weaker than that of ordinary plants, which, through increased evaporation, prevent burns of their photosynthetic organs

The lack of daily transpiration inevitably leads to overheating of plants. And hence the resistance of succulents to high temperatures. German botanist Ashkenazi botanical garden in Heidelberg back in 1875 he established that the rosettes of sempervivums on a clear sunny day heated up to 54 ° C, (Fig. 2) which is 30 degrees higher than the air temperature and 17 degrees higher than all other plants (Genkel P.A., Margolina K .P., - On the viscosity of plasma in some xerophytes and succulents. In the collection: Abstracts of scientific research for 1945, Department of Biological Sciences.

The maximum temperature of external tissues for living plants - +65 ° C - was recorded in the North. Mexico in one of the prickly pear species. This is not to say that such temperatures are favorable for succulents. Many small species prefer to settle in the shade of the under-crown space of sclerophyte trees and shrubs. Succulents in open habitats, such as large cacti, cover young growth on the crown of the plant with felt-like pubescence and are covered with a thick cover of spines. Prickly pears orient their stems so that they point edge-on toward the hottest afternoon sun. Leaf succulents orient their leaves in a similar way. What about the saltworts that I dug up on the wet salt marsh in the Erlanduz depression? The absence of the CAM type of photosynthesis and living in conditions of constant moisture in the environment (the soil of the salt marsh at the bottom of the depression, as observations showed, remained wet throughout the year) allows us to conclude that they have nothing to do with succulents. Subsequently, already knowing the biology of these plants, I twice tried to cultivate them in dishes without drainage holes in constantly moist, salty soil, which is the opposite of how regular succulents are cultivated. This turned out to be quite a troublesome task, because... Solyanka did not tolerate even short drying. However, in the fall they rewarded me with the fantastic colors of their reddened stems. It may seem that Solyankas do not behave quite typical for desert plants. But that's not true. Unlike succulents, other desert plants also transpirate very actively. But for this they must have - and do have - a source of continuous moisture supply from environment. Such a source for most xerophytes is soil moisture, which is always available at some depth. In other words, if succulents create their own supply of moisture, then non-succulent xerophytes use soil reserves. Here is what G. Walter (1968) writes about this, referring to the Arabian Desert in Egypt: “For the existence of non-succulent species, it is necessary to have a certain amount of moisture in the soil even during the period when their moisture consumption for transpiration is reduced. When water reserves in the soil become insignificant, the plants go into a dormant state. During the transition to a dormant state, the plant gradually dries out, which can be seen by the gradual increase in the concentration of cell sap. Individual plant organs that are less supplied with water begin to die. If this process is not stopped, the plant will die. eventually will die. Perennial species are adapted to endure long-term droughts and reach an age of 100 years or more; they are found in the desert only in places where the supply of water in the soil horizons penetrated by the roots never completely dries up. If rains fall only sporadically and irregularly, then. Here, in practice, only ephemerals can be found, the seeds of which, perhaps, remain in the soil for more than ten years without losing their germination.” The peculiarities of the physiology of succulents are a consequence of the peculiarities of their ecology. If we look closely at photographs of cacti or other succulents in nature, we will almost always notice around them other - non-succulent plants, such as grasses, wormwood, acacias and many, many others. Popularizers of cacti somehow forget about these plants when they talk about the unique drought resistance of cacti. But these non-succulent plants grow in the same conditions as cacti and do well without water supplies. Moreover, we mentioned above that many succulents live in the under-crown space of other xerophytes. So what's the matter? And the point is precisely in the different ecology. Sclerophytes spread their roots deep into the soil, where at least minimum quantity moisture available to them (Fig. 3).

Succulents spread their roots in the very top layer of soil, which dries out within a day after rain (Fig. 4).

Their different biology does not allow them to “take someone else’s place,” but allows them to coexist. Thus, sclerophyllous xerophytes use soil moisture reserves, and succulents use their own. In those habitats where the top layers of soil dry out rarely and for a short time, succulents are not common there, for example, in humid climates. But if in a humid climate there are periodically completely dry habitats, they are occupied by succulents. An example is the numerous succulent epiphytes, in particular, orchids and bromeliads, inhabiting the upper tiers of the crowns of constantly humid equatorial forests - gils. In temperate latitudes this pattern persists. For example, the succulent Sedum acrum settles on sandy soils with low moisture holding capacity in the southern regions of Russia and Ukraine, which are characterized by long summer droughts. Therefore, in our opinion, the concept of succulence includes: morphologically - the presence of water-storing tissues in green organs, assimilation; physiologically - CAM type of photosynthesis; ecologically - living in conditions of periodically complete absence of available moisture in the environment. This definition provides precise diagnostic characteristics of a succulent and distinguishes succulent plants from large number other plants that have one or two characteristics in common with succulents. Their different biology does not allow them to “take someone else’s place,” but allows them to coexist. Thus, sclerophyllous xerophytes use soil moisture reserves, and succulents use their own. In habitats where the top layers of soil dry out rarely and only for a short time, succulents are not common, for example, in humid climates. But if in a humid climate there are periodically completely dry habitats, they are occupied by succulents. An example is the numerous succulent epiphytes, in particular, orchids and bromeliads, inhabiting the upper tiers of the crowns of constantly humid equatorial forests - gils. In temperate latitudes this pattern persists. For example, the succulent Sedum acrum settles on sandy soils with low moisture holding capacity in the southern regions of Russia and Ukraine, which are characterized by long summer droughts. Therefore, in our opinion, the concept of succulence includes: morphologically - the presence of water-storing tissues in green organs, assimilation; physiologically - CAM type of photosynthesis; ecologically - living in conditions of periodically complete absence of available moisture in the environment. This definition provides precise diagnostic characteristics of a succulent and distinguishes succulent plants from a large number of other plants that have one or two characteristics in common with succulents. (Fragment of the article by Sinev I.E. “WHAT DIFFERS SUCCULENTS FROM OTHER JUICY DRY-LOVING PLANTS” in the journal CACTi AND OTHER DRY-LOVING PLANTS, 1999 No. 2)

When we talk about succulents, we are talking about a range of plants that live in areas where rainfall is typically sparse.
To survive, these plants turned their leaves and stems into their own water stores over thousands or maybe even a million years ago.
Thanks to these reserves, they can grow and survive in arid places and even in the desert.

But there is a lot of confusion about what succulents are and how to properly care for them. Let's figure it out.

What's happened succulent plants?
If we start with the term, the word comes from the Latin “suculentus” which means very “succulent”. This means that there are organs or parts of the plant (leaves, stems, trunk) that allow water to be stored in large quantities than other plants.

There are three types of such plants:

• cacti or stem succulents
• leaf succulents
• and plants with caudex

Cacti or stem succulents are plants that are typically characterized by the presence of thorns that cause harm to those who dare to touch them. But the thorns are not always distinctive feature this type of succulent. There are species that have no spines or are so short that they are barely noticeable. There are several examples: Astrophytum asterias, Astrophytum nudum, Echinopsis subdenudata, Lophophora williamsii and others...

Thorns are very useful for cacti: they protect them from the sun, protect them from being eaten by animals, and also help them collect more water. What kind of water? Dew, of course. Drops of dew settle on the thorns, and water flows down the trunk to the roots of the plant.

How can you tell if a plant is a cactus or another succulent? Cacti have . From them grow thorns, if a particular species has them, and flowers.

Cacti take two types of forms: columnar, can reach a height of ten meters, or spherical but you should know that some of them such as Schlumbergera

They come from America, especially from the central part.

Leaf succulents- these are plants that store moisture in their fleshy leaves. The leaves can have an elongated shape, be flattened, thin, round, or grow in the form of a rosette. Their appearance resembles stones or miniature sculptural works made by the artist. Leaf succulents include Aloe, Agave, Sedum, Euphorbiaceae, Crassula, Lithops, and others.

How are they different from cacti? Mainly in two things: they don't have flowers, and the flowers sprout from a terminal stem. There are some that have what look like thorns, such as Euphorbia enopla, but they do not arise from the tree, but from the trunk itself.

Most of them are plants with compact size, which does not exceed thirty or hundreds of centimeters in height. However, there are some shrubby forms with a height of up to two meters or more, as in the case of Crassula ovata.

They originate mainly from Africa and grow in the tropics South America, in Madagascar, but they can also be found in Europe.

Nowadays, various compositions made only from stem succulents and mixed with cacti are in fashion.

Plants with caudex. They are one of the most curious plants because they have normal leaves and flowers, but their trunk does something that a normal tree cannot do: store water in large quantities.

Thanks to this adaptation mechanism, they can withstand quite long periods drought. If they have a problem with lack of moisture, they may sacrifice leaves and even branches. Yes, yes: if they are in trouble, they stop feeding the branch and get rid of it. Then they seal the wound and that's it... they don't need to waste a lot of water.

We can find them in Africa, being the most famous Adenium obesum, Fockea edulis and Cyphostemma juttae.

Fans often classify all plants that have spines and can be stored in the Cactaceae family. own body water. Only with time comes the understanding that not all such plants belong to cacti, although they have a number of similar characteristics.

As a rule, the presence of spines and the ability to store water are signs inherent in a wide group of plants called succulents. We can say that almost all cacti are succulents, but not all succulents are cacti.

What are succulents?

Succulents are not a taxonomic concept and have nothing to do with taxonomy. Succulents (succulentus – juicy, fleshy) – general opinions. This is the name given to a group of perennial drought-resistant plants that are capable of storing water in a highly developed special tissue - water-storing parenchyma and have a number of morphological and physiological adaptations for its economical use during the dry period.

Cacti and succulents. On our planet, wherever there are wastelands and semi-deserts, local plants, independently of their own origin, adapted to living conditions in a similar way.

Currently, there are about 15,000 species of succulent plants, which belong to 80 families. There are many succulents among the plants of the families Cactaceae (cactaceae), Aisoaceae (aizoaceae), Crassulaceae (crassulaceae), Orchidaceae (orchidaceae), Bromeliads (bromeliaceae), Lastovenes (asclepidacae), Agave (agavaceae), Asphodelaceae (asphodelaceae), etc.

Video: How to make leaves for a succulent (marshmallow foamiran)

These plants are very different in shape and their adaptability to survive in low humidity conditions.

It should be noted that succulents also grow in tropical rainforests, ripsalidopsis or hathiora, for example. But more often these are only epiphytic plants; they grow on tree trunks and accumulate moisture during rains, so that later they store it in fleshy stems.

Video: Money tree. What is the difference between replanting and transshipment of Crasula arborescens? Part 5

Cacti and succulents. For example, the branches of cylindroopuntia have turned into oblong segments on which cylindrical fleshy leaves grow, but they are short-lived - after some time they dry out and fall off.

Ball-shaped and columnar cacti are completely devoid of foliage. The stem has only spines and hairs. The spines of cacti are not decoration; they play an extremely important role in their life. Reservoirs of water such as cacti in the middle of a wasteland could not survive unnoticed for long. Therefore, spines are actually the only protection from being eaten for most of them. In addition, spines and hairs protect the plant from heat, wind, heavy rain, and also retain dew and protect the surface of the stem from drying out quickly.

How to distinguish a cactus from other succulents?

By what characteristics can representatives of the cactus family be distinguished from other succulents? Among the characteristics available to the average cactus grower, you need to focus on 5 important ones: all cacti belong to the class of dicotyledons (the seeds of these plants and their seedlings have two cotyledons) - they are perennial succulents - cacti have a special organ called the areola - the ovary of the fruit in cacti is lower - the fruit of cacti is a berry.

Cacti and succulents. From the point of view of an amateur, a more important sign that a plant belongs to the cactus family is the presence of areoles. It can be assumed that the areola of the cactus fits the shoot and axillary bud deciduous plants. The upper and lower parts of the areola have different functions. On the upper lobe, which corresponds to the axillary bud, buds and young shoots appear in species that branch. The lower part, which corresponds to the shoot, produces spines, which in cacti are simply separated from the stem: cactus spines are an independent organ.

The concept of “inferior ovary” means that in cacti, the part of the flower from which the fruit will develop after fertilization is located below the petals (as, for example, in cucumbers).

The fruits of cacti, regardless of size and shape, are always eaten as ordinary berries: their small grains are kept in the pulp, covered with a leathery skin.

The listed 5 signs allow you to firmly determine whether your plant belongs to the cactus family. However, if, as a result of the check, your initial diagnosis is not confirmed and your “cactus” turns out to be an “impostor” - this is not a reason for despondency. It is rare to come across a collection of cacti that does not contain a single other succulent. This natural group of plants is so large and diverse that it is virtually impossible to ignore them.

Cacti and succulents. In indoor culture, both cacti and other succulents are extremely widespread. Many cactus enthusiasts collect huge collections of these mind-blowing plants.

Most succulents grow slowly and do not require special care, making them ideal for creating plant compositions, all kinds of desert gardens, and small landscapes.

Very often we confuse cacti with succulents. All these plants are adapted to drought, their tissues are thick, fleshy, often even prickly! But how do cacti differ from succulents from a botanical point of view?

One is prickly, the other is not. This is the principle.

Succulents

Succulents are very well adapted to drought. These fleshy plants can actually store water in their leaves, stem and roots. In addition, they have a special structure: the leaves are usually small, covered with a thick epidermis, sometimes with wax or even hair. Goal: retain as much water as possible in the leaves.

In terms of classification, succulents do not belong to either a group or a family. Quicker, we're talking about about plants with common morphological characteristics, but having nothing in common with each other.

cacti

Cacti are succulent plants that contain water in their tissues, which allows them to withstand long periods of drought. All cacti belong to the same family: Cactaceae. Cacti differ from other succulent plants by the presence of areoles - small hairy or woolly tufts located at the base of their spines.

Most cacti have needles. In some they are small, jagged, thin, united in bunches. They are usually very difficult to remove from the skin. The spines of cacti are like the branches and leaves of other plants, which in the course of evolution turned into thorns in order to lose less moisture, protect the plant from herbivores, and let sunlight, in some cases, create an insulating layer between the plant and the hot air of arid climate zones.

To summarize, cacti are succulent plants with thorns, while succulents are generally thornless. And as always, the exceptions prove the rule, there are thornless cacti and spiny succulents.

Note:

In addition to the typical areoles, the structure of the flowers and fruits will also help determine whether we are dealing with a cactus or another plant. However, these characteristics are not used very often (and the plant must bloom!).

Succulents: what a variety!

Succulents can be found in numerous botanical families, the existence of which few people realize. Their characteristics are more or less obvious: there is no doubt that echeveria is a succulent, with begonia but this is not so obvious.

Family Tolstyankov is one of the most typical families of succulents: it includes numerous succulent plants such as Crassula, Kalanchoe, Echeveria, Sedum, Sempervivum. Did you know that according to the classical classification, succulent plants of the genus Haworthia belong to the family Liliaceae(How lilies or muscari), as well as aloe (aloe vera)? Dracaena And sansevieria with its hard, thin and pointed leaves, they are not at all similar to the juicy and fleshy ones Lithops(“living stones”), however they also belong to succulents. The stems of some succulents with water reserves are more eye-catching than their leaves, such as bocarnei. Finally, some types milkweed(family M Olochaceae) look like cacti (we are talking about cactus-shaped plants), but are not them: for example, spurge heptagonal can often be found on store shelves among cacti.

The habitats of cacti are strikingly different from each other climatic conditions. In northern Canada there are winters with temperatures down to -40°C and deep snow.

In the south North America- in Nevada, Utah and Arizona - cacti have to endure not only heat, but also snow. Prolonged drought coupled with extreme heat is common in Southern California, Texas and New Mexico. The weather conditions are the same in Mexico.

Heat-loving species of cacti live in subtropical and tropical conditions southern Mexico, Central and South America.

North American cacti

Cacti of Mexico and the southern states of the USA

In Mexico, cacti have long been used as building material, food and medicine. The national emblem of Mexico depicts a cactus.

South American cacti

The genus Oreocereus includes many species of cacti. different sizes and shapes - from small spherical to large columnar. Characteristic feature Plants of the genus Oreocereus are soft hairs that protect plants from strong temperature changes in the mountains.

The northern Chilean and Peruvian deserts are often foggy and experience virtually no rain. Such conditions are suitable for the genera Haageocereus, Cop'apoa, Neoporteria, Pygmecereus, Islaya, Eulhinia. These cacti obtain moisture exclusively from fog.

Despite the harsh weather conditions in Central Peru, cacti of the genus Oroya, Matucan, Tephrocactus, and Lobivia are widespread here.