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The CACTUS

What is it ?

Signification of the word cactus

Cactus, family including/understanding two thousand species of plants charnues and thorny, originating in America and present also in Australia, Africa and in the Mediterranean area. The majority of the species are adapted to the arid climates. The fruits (prickly pears, for example) represent a source of food and drink. Their curious forms, and the little of care that they require, made them very popular like plants of interior, which constitutes a danger to certain species.

The plant of cactus generally consists of thorny stems and of roots. The sheets are almost absent, or present in the form of spines. Two kinds only have completely formed sheets. The stems are usually inflated and charnues, adapted to the storage of water (it is for that that they are called " succulent plants"). The roots form wide area networks located as a majority close to the surface of the ground, some rare the deeper having primarily a role of fixing. In the desert, the individuals generally are very spaced.

The family of the cacti comprises from thirty to two hundred kinds according to authors'. The majority of the kinds are cultivated for decorative reasons, the small species with slow growth being appreciated more.

History of the cactus

According to the layer of fossil of Utah, the geologists think that the cacti appeared as of the Eocene (group of tertiary grounds of the period). They for the first time were discovered by the colonists of the new world (either Amérique)et people immediately considered the aspect curious about these plantes(ce which in made a passion). With the wire of time cactées diversified there, certain found in Africa and to Ceylon would have been transported by the birds during their migrations. Today they live of everywhere, in the desert, the steppes, Mexico, Brazil, the United States and even in the areas of Mediterranean climate. One finds plants succulent in practically all the supermarkets and garden-center, these plants are unequal qualities insofar as they are not always suitably treated at the end of the culture; more conditions of sale are not always very good and they are also badly acclimatized.

 

SMALL PANORAMA OF THE WORLD OF THE SUCCULENT ONES

 

Let us give the things to their place! Although some are edible, the term of " succulent " indicates, in scientific language, the fatty plants, i.e. all the species which have significant reserves of juice in their stems or their sheets.

These reserves make it possible succulent to resist the dryness during many months, even of the years, without any contribution of water. The quantity of water included in the cells of storage can represent more 90/o total mass of the plant. When a succulent plant is sliced whose reserves are located in the stem, one cannot observe of wood with concentric scratches, but of the turgescent cells, distributed all around a central beam of vessels where the sap circulates. The green chlorophyllian fabrics are located right under the skin

In addition, as opposed to what it is thought sometimes, the fact that the succulent ones carry spines or not is not most significant, because certain thorny plants are not the succulent ones. The principal criterion for the specialists consists of the presence of a particular metabolism, known as CAMWOOD (acid metabolism of the Crassulaceae), which makes it possible this type of plants to fix carbon dioxide during the night, contrary to the ordinary plants. In the course of the day, the stomates are closed and photosynthesis is carried out starting from the carbon reserves made up during the night. This particularly sparing metabolism in energy, associated an enormous storage capacity, is the secrecy of the incredible resistance of this type of plants.

But it should well be realized that despite everything their qualities, the succulent plants cannot survive eternally an absence of rain. This kind of plants thus does not push in the completely desert zones One meets them in the semi-arid or moderated zones, where it rains more than 250 mm of water per annum. The habitat of the cacti and succulent is characterized by one dry season of long duration, followed by a short wet season, period during which the plants push and constitute the maximum of water reserves.

There are approximately 12.000 species of succulent plants, distributed in about thirty botanical families. The cacti belong exclusively to the botanical family of Cactacées, which is remarkable by the fact that all its members are succulent plants. In the other families cohabit of the fatty plants and the mésophytes ("normal " plants).

 

THE FAMILY OF THE CACTÉES OR CACTACÉES

This family originating in America counts approximately 2.000 species. She has the effect of having areolas, kinds of duveteux bearings on which spines are established. Cactées do not have a sheet, except rare exceptions, and it is supposed that the spines result from the reduction of the sheets or the side buds. The areolas are bodies independent of the skin of the plant, which can be detached by leaving a clear scar. For a long time, the term of pivot prevailed to qualify the prickles of the cacti, but it was an error. The pivots, with the strict botanical direction, result from transformations of the skin, but they are not distinct bodies which one can detach more or less easily. One must thus speak about spines for Cactées, and hold well the term of pivot for the succulent plants others that Cactées.

The classification of the family of Cactées is rather complicated. Many books devoted to this family briefly tackle this polemical subject, but rare are the authors who could propose a classification in the form of monograph, because it is a gigantic work, constantly called into question by new discoveries.

1. The group of Cereus (Latin candles) comprises column-like species (fig. A). Into growing old, certain species can ramify (to emit branches) when they reach a sufficient height of trunk, which can lie between 50 cm and several meters, which asks obviously long years (fig. B). Others divide base more or less quickly, by forming groups resembling organ pipes (fig. C), or are spread out over the ground and push while moving away from their base (fig. O). There are also candles climbing in the tropical forests (fig. E).

2. The group of Cactées globular consists of all the more or less spherical species. One can distinguish the balls solitary, which produce never rejections (or then when they are very old), spherical or slightly flattened (fig. F), those which push in cluster of balls (fig. G), the solitary plants passing quickly from the state of sphere to that of short cylinder (fig. H), finally the species forming of the tufts of short cylinders (fig. 1). The plants of this group represent one of the most advanced phases of the family.

 

Image1cactus kuentz.jpg (21804 octets)

3. The group of Opuntia or opuntias is characterized by the
simultaneous presence of large pivots and glochides (tiny spines
gathered in bearings). Seen under the microscope, the two types of
spines reveal a point in the shape of harpoon, whereas other Cactées
are provided with pivots with smooth point. It is what explains the
difficulty with which one withdraws them skin. Opuntia can take three
principal forms. Most typical is the superposition of flattened
articles, in the shape of pallets or rackets (fig. 1). Another very
decorative form is the bush, made up of very thorny cylindrical
articles, from where names sometimes employed of Cylindropuntia and
Austrocylindropuntia (fig. K). More astonishing, certain opuntias,
such as Tephrocactus, evolved to more or less spherical forms (fig.
G).

4. Cactées épiphytes with stems punts (fig. L) or falling down
(fig. M) live perched in the trees of the tropical forests of Central
America, and draw to them pitance from the leaf mould broken up.

5. The group of Pereskia comprises not very advanced species, i.e.
shrubs having at the same time null and void sheets and pivots (fig.
NR). They are the " ancestors " of famille.évoluées of the family.

Image2cactuefrs Kuentz.jpg (23319 octets)

6. Cactées present sometimes curious anomalies of growth, which one names " monstrosity " and " cristation ". In the first case, it is about a proliferation of heads pushing in all directions, which gives to the subject a pace of rock tormented (fig. X). The kinds most concerned are Cereus and Opuntia. The cristation is a badly explained phenomenon which makes push the final bud in the direction of the width. The plants reached take initially the form of a peak, then undulate, and end up resembling brains (fig. W). All Cactées column-like and globular, as well as Opuntia cylindrical, can be touched by this anomaly, which remains however rare because it cannot be caused. One did not find yet a cristation for all the existing species.

 

THE FAMILY OF THE EUPHORBIACÉES

This family is very interesting, because it comprises nearly 10.000 species, of which a thousand of succulent, for the majority African, distributed in the kinds Euphorbia, Monadenium, Synadenium, Pedilanthus and Jatropha. The convergent evolution of Cactées and the succulent euphorbiums at a distance of thousands of km led to the appearance of the shapes of equivalent plants. Euphorbia do not have however areolas, nor with spines, but are often provided with hard points or pivots. It contain, moreover, one toxic sap of milky appearance, the latex.

One finds in this group much arborescent species ramifying (fig. B) quickly and of thorny bushes (fig. K). Madagascar shelters many thorny and leafy species (fig.N). There are also some rare spherical species (fig. F), cylindrical (fig. Fi), recluses or touffues (fig. G). Euphorbia are sometimes touched by the phenomenon of cristation the most original forms which the members of this very polymorphic family can take, one will quote the caudex (fig.Y1), the " head of Jellyfish " and the " coral " (fig. W).

         Image3cactus Kuentz.jpg (25522 octets)

AGAVACEES AND AL0ACEES

These two families of monocotylédones present morphological analogies. The Agave kind is the principal member of the family of Agavacées. These plants are originating in America, but were largely widespread in the whole world by the man. The sisal plants are presented in the form of rivet washers of pointed sheets (fig. P). Sansevieria are also classified in this family, but come from Africa and Asia.

Three African kinds of Aloacées are very widespread in culture Aloe, Gastena and Hawoi-thia. Also pushing in rivet washers of pointed sheets, one often confuses Aloe with the sisal plants. The aloes are a little with the sisal plants what the euphorbiums are with the cacti of the plants which, remotely, evolved/moved in the same way, but which remains quite distinct from a botanical point of view.

 

THE FAMILY OF THE CRASSULACEAE

One finds in this family of the plants of small size, deprived of spines, with sheets charnues, and of culture very easy Crassula, CIF yledon, Kalanchoe, Echeveria, Pachyphytum, Sedum, Sempervivum, Aeonium... Many species can push in rivet washers of more or less round sheets (fig. Q), stemless or going up in small trunks (fig. R). The others have sheets established per pairs, supported by robust stems forming shrub (fig. S), or of the more or less flexible stems (fig. T), even crawling (fig. U). These the last two types lend themselves well to the culture in suspension. Some rare species are cristent (fig. W).

 

THE AÏZOACÉES (MR. ESEMBRYANTHÉMACÉES)

This South-African family is comparable with the family of Cactées, in this direction qu it is made up only of succulent plants. She is divided into three principal forms. The species buissonnantes and crawling with strong vegetation (fig. T & U) are recruited among the " ficoïdes, Lampranthus, Delosperma, Mailephora and Oscularia mainly. The mimetic species or " plant-stones (fig. V2) are of curiosities of nature. These miniature plants, often hidden in sand, resistant to terrible drynesses, have as a name Lithops, Argyroderma, Conophytum, Ophtalmophyllum. The third group is composed of intermediate species, pushing in compact tufts (fig.V1) Faucaria, Pleiospilos, Cat-ruanthus, Glottiphyllum, etc. Many Aizoacées have an interesting flowering, but none presents cristation.

 

ASCLÉPIADACÉES

Two groups of very different plants cohabit in this family. First is composed of the kinds rarer Stapelia, Caralluma, Huernia and other kinds. They are plants pushing in low tufts, deprived of sheet and spine, whose stems generally present four or five coasts (fig. O). Their flowers, very surprising, have the star shape with five branches, and feel very bad. There are some cristées species.

The second group includes/understands species with the voluble stems, lianas whose principal representatives are Hoya, Ceropegia and Cynanchum.

         Image4cactus Kuentz.jpg (25903 octets)

OTHER FAMILIES

Broméliacées (Hechtia, Dyckia, Puya) resemble pineapples. Their sheets laid out in rivet washers are in general very coriaces and thorny.

Composed or Astéracées (Senecio, Othonna) are nonthorny plants, of very varied appearance. Portulacacées (Portulacaria, Anacampseros) resemble the Crassulaceae, but their flowers last only a few hours.

Apocynacées (Adenium, Pachypodium) have reinflated trunks and not very succulent sheets (fig.Y2). This type of plant is known as " pachycaule ", the term of " caudiciforme " indicating, as for him, the species of which only the underground part is reinflated, and who emit voluble stems, like Ipomoea of the family of Convolvulacées or Testudinaria of the family of Dioscoréacées (fig.Y1).

One also finds the succulent ones in Vitacées (Cissus, Cyphastemma), Bombacacées (Adansonia, Bombax), Géraniacées (Pelargonium, Sarcocaulon), Labiées (Caleus), Moracées (Dorstenia), Pipéracées (Peperonia), Passifloracées (Adenia) and much of other families.

 

The substrate

here is a stage significant to respect for cultivating the cacti well, certain people do not put questions, they prefer outward journey to buy ground for cactus already ready with employment, it are a good solution, remain has to choose good quality sold with a description of its composition. So on the other hand you want to manufacture your own ground of cactus it is enough to have the ingredients that here:

1.compost: organic matter rich person; universal compost fear of making the deal.

2.sand: coarse preferably to support the drainage and not-limestone, one can use for example sand extracts from the careers, the sand of constructions, etc

3.pearlite: light and porous, it makes it possible to air the substrates, to avoid putting some in quantity because it retains water easily. One can find pearlite in certain horticulturists.

4.pozzolana: that resembles has blast-furnace slag, it is an ideal material for aired and drained the substrates. One can find it in the garden-centers.

5.gravel and granite: even thing that for sand, one can find some in careers, rivers, etc

6.vermiculite: very light and insulator, it makes it possible the substrate to breathe, one can find it in the material wholesalers of insulation.

7.expanded clay: very light and porous, they are small terracotta balls, one can easily find some in the garden-centers.

8.ground of garden: clay, limestone, himus, trace elements; all these materials are present in your ground whatever the area or you live. You can mix it with your substrate, your plants will be more solid and more resistant to the dryness.

For what conserne the amounts, you can put in an unspecified pot for example 2/5 of quite granulous sand, 1/5de compost accompanied by a little fair peat and crushed clay balls, 1/5 of the remainder c.à.d pozzolana, vermiculite, pearlite, gravel, D granite and 1/5 of ground of garden.

 

For the exposures, manures, the treatments and the plantations in the open air, please thank you refer to the page " the good councils "

 

      

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Ets.KuentzThe world of the cactus("the small panorama of the world of the succulent plants " results from its catalogue)