Asteraceae are the largest family of dicotyledonous plants. It contains from 1150 to 1300 genera and more than 20,000 species. Asteraceae are found almost everywhere where the existence of higher plants is generally possible - from the tundra to the equator, from sea coasts to alpine snows, on barren sands and on rich black soils.
Plants of this family are usually easy to distinguish from representatives of other families by their characteristic inflorescence - the basket. The base of the basket is formed by an expanded bed of the inflorescence, or a common receptacle (Fig. 245), on which flowers closely adjacent to each other are located. Outside, the common receptacle is surrounded by an involucre consisting of more or less strongly modified upper leaves. The main function of the wrapper is to protect the flowers from adverse external environmental influences. The leaflets (or leaflets) of the involucre are arranged in one, two or several rows. The sizes of baskets in wild asteraceae are most often small - with a diameter ranging from one to several centimeters. Only occasionally the baskets are larger - up to 10-15 cm in diameter, and in the cultivated annual sunflower (Helianthus annuus) they reach the size of a large dish in diameter - up to 60 cm. At the same time, many wormwood baskets are tiny - only 2 in height and width -4 mm. The general receptacle can be more or less flat (as, for example, in a sunflower), but can also be concave, convex, cone-shaped or of other shapes. Its surface is often covered with films, bristles or hairs. These are modified bracts, and only the hairs may not be associated with the bracts (i.e., have a trichome nature). The number of flowers in the basket is also in certain correspondence with the size of the general receptacle. In annual sunflowers it often exceeds a thousand, but in the female inflorescences of species of the genus Ambrosia there are only 2 flowers, and the baskets of species of the genus Echinops contain only one flower (Fig. 246).
The flowers of Asteraceae are usually small. The calyx is modified into a pappus (sometimes also called a fly or pappus). The pappus consists of a more or less significant number of different types of bristles, hairs, awns, or it is represented only by a membranous rim (crown). Sometimes the tuft disappears completely, and then the flower is completely devoid of a calyx. In more primitive Asteraceae, scales are clearly visible - the rudiments of a lobed calyx. The corolla is fused-petalled. Its shape varies greatly. It is more or less actinomorphic, in which case it is tubular; if the corolla is zygomorphic, then it is most often either ligulate or so-called bilabial. There are many transitional forms between these basic forms.
The stamens, usually 5 in number, are attached to the corolla tube. The filaments of the stamens are free, and the anthers stick together with their sides, forming an anther tube through which the style passes. The anthers are mostly elongated, longitudinally dehiscent, introsular. Rarely, for example, in the genus Ambrosia, the anthers are free, and the filaments of the stamens are fused. The gynoecium consists of 2 carpels with a style that ends in 2 stigmatic lobes or branches; in sterile flowers the style is sometimes undivided. In fertile flowers, the lobes of the style protrude from the corolla and often diverge greatly. On the inside of the stigma blades, they are equipped with a special receptive (stigma) tissue. Many species of the family are characterized by the presence of so-called collecting or sweeping hairs, which help remove pollen from the anther tube. The location of these hairs (in the form of a collar under the stigmatic lobes or on a more or less significant extent of the outer side of the lobes), their density and length are very diverse. The ovary is inferior, unilocular, at the base with one ovule (very rarely there are two), located on a short placenta (funiculus). In mature seeds, there is no endosperm or only traces of it are found.
The fruit of Asteraceae is an achene. This is a single-seeded, indehiscent fruit with a more or less dense, leathery and usually thin pericarp, usually separated from the seed. Only in very rare cases, as in species of the neotropical genus Wulfia, are achenes with a succulent pericarp.
Brief information about the flower and associated structures, which were described above, refer to the well-developed bisexual flower of the Asteraceae. However, not all species of this family have all the flowers in the basket bisexual and fertile. Often there are 2 more types of unisexual flowers - female (usually fertile) and male (sterile), as well as sterile flowers in which both the androecium and gynoecium are reduced. The basket can be uniformly flowered (homogamous), but more often heterogeneous (heterogamous). In this case, the center of the basket is occupied by bisexual tubular flowers, and female and often brightly colored reed flowers radiate along the periphery. In a heterogamous basket, other combinations of flowers are observed, different in structure and sex.
The leaves are mostly alternate. The size, shape and degree of dissection of the leaf blade vary greatly, from very large, like that of the Japanese butterbur (Petasites japonicus), growing on Sakhalin, the Kuril Islands and Japan (the blade of its entire basal kidney-shaped leaf reaches 1.5 m in diameter, and the petiole 2 m long), to small, very reduced ones, like those of the American leafless baccharis (Baccharis aphylla) with twig-like photosynthetic stems. The leaves of some American vines from the genus Mutisia (Mutisia, Fig. 247) are very original. In most Asteraceae, the leaves are characterized by one or another type of pinnate venation. However, there are leaves with strictly parallel or parallel-arcuate venation, as in some species of the genus Scorzonera.
Many Asteraceae are characterized by pubescence. The hairs of Asteraceae are very diverse: single- or multicellular, hard and soft, straight and tortuous, simple (unbranched) or bifid, star-shaped. Dense pubescence is especially often well expressed in species living in conditions of constant dryness or sudden changes in temperature. Thus, growing in Central Asia, cotton wool (Lachnophyllum gossypinum) in its young state is covered, like cotton wool, with soft tangled hairs. Speaking about the aerial parts, we should also mention the noticeable percentage of thorny plants among the Asteraceae. The leaves and stems are prickly.
The vast majority of species of the family have a developed taproot. Often the root is tuberously thickened, which, for example, is characteristic of burdocks (species of the genus Arctium). Many species of the family develop contractile (retracting) roots; in plants with a basal rosette, they often ensure that the rosettes adhere tightly to the ground. In subshrub and subshrub Asteraceae, the taproot is usually woody and well developed. In addition, they form the so-called caudex or stem root - a perennial formation, mainly of shoot origin. The caudex carries renewal buds and often serves as a site for the deposition of reserve nutrients. The beautiful tree plant (Fitchia speciosa), growing on the island of Rarotonga (Cook Islands), has well-defined aerial supporting roots. Endomycorrhiza has been found in many Asteraceae.
Most Asteraceae are herbs, either perennial or annual, that range in size from very large, like some sunflowers, to tiny. But among them there are also many subshrubs and shrubs. Shrubs - from 1 to 5 m and only sometimes higher (up to 8 m). Trees, usually low, are also found among the Compositae. Many tree forms are characteristic of oceanic islands. As part of the genus Scalesia, endemic to the Galapagos Islands, species are known with trunks reaching a height of more than 20 m with a diameter of 25-30 cm, such as S. pedunculata. They form real forests. Charles Darwin mentions them in his famous “Diary of Research in Natural History and Geology...” (better known to Russian readers under the title “A Voyage Around the World on the Beagle Ship”). In South Africa and Madagascar, dioecious woody plants of the genus Brachylaena grow, and among them is a tree of the first size, endemic to Madagascar, Brachylaena merana. It reaches a height of 40 m and a diameter of up to 1 m; Its wood is resistant to rotting and is highly valued.
Among the tree-like Asteraceae there are so-called rosette trees. Their trunk does not branch or weakly branches and bears a crown of leaves at the top like a bunch or rosette. Rosette trees from the genus Senecio reach a height of 7.5 m. They are characteristic of the landscapes of the highlands of the African tropics. Many Asteraceae are cushion-shaped. Thus, Haastia pulvinaris, growing in the subalpine and alpine zones of New Zealand, forms pillows with a diameter of over 2 m and a height of 60 cm. Haastia, together with another cushion-shaped asteraceae - Raoulia eximia - due to its light, dense pubescence, stands out well among the stones.
Lianas are rare among Asteraceae. Large vines are known in the genera Vernonia, Mikania, Mutisia, Fig. 247 and a few others. All of them are inhabitants of warm countries.
Among the Asteraceae there are many leaf and stem succulents; many of them are found in garden-greenhouse culture. The largest number of succulent asteraceae live on the southern tip of Africa and further northeast to Ethiopia, as well as in Madagascar.
Aquatic plants are rare among the Asteraceae. The most famous are the North American Sclerolepis uniflora and two species of the genus Bidens. The original aquatic Mexican species are water pectis (Pectis aquatica) with a floating stem about 30 cm long and semi-submerged small-petalled heteromorphic (Erigeron heteromorphus), the upper leaves of which are entire or serrated, and those immersed in water are hair-like. An aquatic plant with opposite, thinly dissected leaves, Cotula myriophylloides grows in South Africa.
In some Asteraceae, the stems are modified in phylloclady and take on the function of photosynthesis. This is observed, in particular, in several American species of the genus Baccharis, for example in Baccharis articulata.
Like representatives of the order Campanaceae, the main storage carbohydrate in Asteraceae is inulin (and not starch, as in most other dicotyledons).
Many Compositae belong to plants with a high degree of sensitivity to light, which is expressed in the ability to open and close the baskets depending on the intensity of light. Often this sensitivity is so pronounced that it is easy to observe without resorting to any instruments. That is why among the flower clocks that were proposed in the first half of the 18th century. K. Linnaeus, Asteraceae are especially numerous. Flower clock is a set of plants planted in a small area, the flowers of which open and close at a certain time on clear sunny days. The accuracy of such watches is from half an hour to an hour. For each area, the set of plants should be different, previously established by observations.
Among the Asteraceae there are so-called compass plants. At midday, they are able to position their leaves with their edges facing the light falling on them; in this case, one wide side of the plate faces east, and the other faces west. This arrangement of leaves protects against overheating by the sun's rays and helps reduce transpiration, without reducing the intensity of photosynthesis. Compass plants are usually inhabitants of open areas. Among such plants, the wild or compass lettuce (Lactuca serriola), widespread in Eurasia, and the North American lobed silphium (Silphium laciniatum) are well known. At a time when the vast expanses of the American prairies were still poorly developed, the position of silphium leaves replaced a compass for lost hunters.
The responsiveness of some Asteraceae not only to light, but also to air humidity and other atmospheric phenomena has long been noted in the community. Therefore, species of this family serve as a kind of barometer. So, if the basket of the sow thistle opens on a more or less clear day, then rain is very likely the next day. The literature also contains data on longer-term “predictors” of weather among Asteraceae; it is indicated, for example, that the formation of a rosette of leaves in Helenium autumnale is associated with the nature of the upcoming winter.
The vast majority of Asteraceae are insect-pollinated plants. Early spring species from temperate regions often have golden or orange-yellow flowers in the basket, which stand out well in dark soil that is still lightly covered with other plants. In many Asteraceae, the inconspicuous tubular flowers of the basket are surrounded on the periphery by bright white, yellow or red large flowers, which are clearly visible from a great distance. These peripheral flowers are often sterile and perform no other function other than signaling. Insect-pollinated Asteraceae with small baskets, hardly noticeable individually, have more or less large, clearly visible common inflorescences.
Insects visiting Asteraceae are attracted by nectar, usually secreted at the base of the style, as well as pollen. The main pollinators are bees, wasps, bumblebees and other Hymenoptera, as well as Lepidoptera. More rare pollinators are hoverflies (syrphids) and other dipterans, as well as beetles and representatives of other orders of the insect class. Often the same Compositae is visited not by one or two, but by a large number of different species of insects. There is evidence that some species of the genus Mutisia are pollinated by birds.
Most Asteraceae exhibit protandry. Just like in bellflowers, the anthers open while still in the bud and the pollen ends up inside the anther tube even before the flowers open; at this male phase of flower development, the style is still short and the lobes or branches of the stigma are still tightly closed; by the time the flower opens, the column lengthens and gradually, like a piston in a cylinder, pushes out pollen, as we have already seen in representatives of the lobeliaceae subfamily of the bellflower family.
Of the features that ensure the success and accuracy of cross-pollination, of great interest is the peculiar pollen-feeding mechanism observed in quite a few Asteraceae, for example, in species of the genus cornflower (Centaurea, Fig. 248). They have sensitive filaments of stamens that have the ability to contract. As a result, when insects touch the stamens, the anther tube moves down, and the column with sweeping hairs located underneath carries out pollen, which falls on the insect. Many Asteraceae have adaptations that ensure pollination between different flowers within the same basket.
In cases where cross-pollination for some reason does not occur, self-pollination usually takes place. It is ensured by the ability of the stigmatic lobes of the style to twist so that they come into contact with their own pollen.
In relatively few Asteraceae, for example in species of the genus cocklebur (Xanthium, see Fig. 246), protogyny is observed. Anemophilia is common. It is considered as a secondary phenomenon and is characteristic of plants of wide open spaces, for example, species of wormwood (Artemisia); their baskets, as a rule, are small, inconspicuous, collected in complex common inflorescences.
Some Asteraceae have cleistogamous flowers.
In addition to the normal sexual process, apomixis is often observed in Asteraceae, especially among representatives of the lettuce subfamily, for example in the genus Dandelion (Taraxacum).
The number of fruits is very significant, and in many cases extremely large. The fruits are usually small and weigh negligible. The length of the achenes often does not exceed 5 mm and the width is 1 mm. The largest fruits are found in the above-mentioned arboreal plant; they reach a length of 5 cm. Very often, the achenes are equipped with hairs, bristles, papillae, and so on, and in some anthemideas (tribe Anthemideae), the achenes are covered on the outside with special mucilaginous cells, which apparently contribute to the germination of the primordia in dry conditions.
Among the Asteraceae there are many anemochores. Of primary importance for this is the tuft, located directly at the top of the achene or raised on an extended narrow tip - the spout. Typically, the crest consists of a different structure of hairs or bristles, which are hygroscopic and can act as a flying machine only in dry weather. The crest belongs to the most perfect adaptations of this genus in the plant world; its position - above the center of gravity - is especially successful when the crest is on the nose. In general, the crest-parachute of Asteraceae, as shown by special studies, is, as it were, calculated according to the exact laws of aerodynamics; it gives the achenes significant stability in flight and increases the dynamic lifting force acting on the achenes. The crests of Asteraceae with feathery hairs are especially perfect. Here it is appropriate to recall that the first printed work of the remarkable Russian botanist V.I. Taliev, published by him in Kazan in 1894, is devoted to a detailed study of the mechanism of movement of hygroscopic hairs of the tuft. Lecocarpus pinnatifidus, a shrub endemic to the Galapagos Islands, has a flying apparatus made of a covering leaf.
Very small and light achenes of Asteraceae, such as those of wormwood, although they do not have a special aircraft, are also partially carried by the wind.
In Asteraceae, which grow near water, the primordia are often carried by water, for example, in some species of butterbur (Petasites), string (Bidens), etc. In the creeping chorisis (Chorisis repens), in the USSR, growing in the Far East on the sands and pebbles of sea coasts and at the mouths of large rivers, the achenes have a thickened, porous shell - an adaptation to their dispersal by water.
Among the Compositae there are many zoochoric species. In the desert ephemeral Koelpinia linearis, the achenes are seated on the back with hooked spines and, in addition, end at the end with a bunch of the same spines collected in the form of an anchor. Thanks to this, Kelpinia fruits stick to animal fur and human clothing. In burdocks, when the achenes ripen, entire fruit baskets easily break off from the plants and, thanks to the tenacious leaves, the wrappers stick to the hair of animals and people’s clothing. For a relatively small number of species, the phenomenon of myrmecochory was also noted. The fruits of some Asteraceae are dispersed when their elastic stems or peduncles are swayed. These are the so-called ballista plants. Their achenes are completely without a tuft or have tufts of coarse hairs, and sometimes are too short to be suitable for dispersal by the wind.
There are achenes that can crawl some distance from the mother plant, as, for example, in blue cornflower (Centaurea cyanus) and common cornflower (Crupina vulgaris). The pappus of these plants is too small for anemochory. But thanks to the hygroscopic movements of the bristles of the pappus, falling down during rain and spreading out in dry weather, the achene is able to crawl.
Among the Compositae there are also representatives belonging to the tumbleweed life form. They are characteristic of plants living in open (treeless) spaces, for example in the steppes. An example of them is the spreading cornflower (C. diffusa), which in the USSR grows in open places, mainly in the south of the European part and in the Caucasus. Another example is the dwarf asteriscus (Asteriscus pygmaeus). It is an annual plant distributed from the Sahara to Balochistan and has hygroscopic involucre leaves. After the achenes ripen, these leaves close, and the plant can remain in this state for 8-10 months. The dispersal of achenes, associated with the opening of the involucre, occurs in wet weather, which contributes to their successful germination.
In the last few centuries, when communication and transportation of various goods between continents and countries became intense, the exceptional fertility of some Asteraceae, combined with their unpretentiousness, allowed them to develop vast new spaces, many times larger than their original (natural) range. An example is the North American conyza (Conyza canadensis), which first appeared in Europe only in the 17th century. and now has become a cosmopolitan. There are also well-known cases when European Asteraceae, having arrived on other continents, began to displace the aborigines there. Thus, drooping thistle (Carduus nutans), introduced to North America from Europe at the end of the last century, has now become a widespread and difficult to eradicate weed there.
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Among the biological features of Asteraceae achenes, let us also mention the heterocarpy, or heterocarpy, observed in many species of this family. Heterocarpy is well expressed in the officinalis calendula (Calendula officinalis, Fig. 249, table 64), widely known for the shape of its curved achenes called “marigolds”. In one basket of calendula there are claw-shaped, navicular and ring-shaped achenes, as well as transitional forms between them.
The Asteraceae family is divided into 2 subfamilies: Asteraceae (Asteroideae), which unites the vast majority of genera of the family and includes 11-12 tribes, and a more homogeneous subfamily of Lettuceae (Lactucoideae), or Chicoryaceae (Cicliorioideae), which includes only one tribe. We have the opportunity to touch only on some of the most important tribes.
Forest herbaceous plants
Asteraceae Image of 12 inflorescences of Asteraceae Scientific classification Kingdom: Plants Division: Angiosperms ... Wikipedia
- (Asteraceae, or Compositae) family of dicotyledonous plants; includes about 25 thousand (according to other sources, 13-20 thousand) species (900-1000 genera), distributed throughout the globe and represented in all climatic zones. Most S.... ...
Asteraceae, order (Asterales) of dicotyledonous plants and units, family (Asteraceae, or Compositae) of this order. Herbs, less often subshrubs, shrubs, tree-like forms (so-called rosette trees) and trees (in the tropics). Inflorescence basket,... ... Biological encyclopedic dictionary
GOLDENROAD OR GOLDEN ROD (SOLIDAGO VIRGAUREA L.)- see Perennial with oblique, short rhizome and straight, bare or pubescent stems, 20-80 cm high. With winged petiole, ovate or spatulate; stem leaves petiolate or upper sessile, oblong or lanceolate, acute, ... ... Forest herbaceous plants
MYCELIS MURALIS (L.) DUMORT.- see. Perennial or biennial with a short vertical rhizome and single bare stems, branched at the top, 30-120 cm high. The lower ones are rosette-shaped, with long winged petioles, lyre-shaped and pinnately dissected, with... ... Forest herbaceous plants
TsMIN, OR SANDY IMMORTELLA (HELICHRYSUM ARENARIUM (L.) MOENCH)- see Turfy, tomentose perennial, with shortened vegetative and elongated generative shoots. The stems are 15–40 cm high, unbranched, straight, with remnants of dead leaves on the rhizome. The lower leaves are petiolate, linear... ... Forest herbaceous plants
KITAMURA, OR KOMAROV'S UNDERripening (CACALIA KITAMURAE NAKAI (C. KOMAROVIANA (POJARK.) POJARK.)- see. Perennial with a creeping rhizome and a stem 1-2 m high, furrowed and pubescent at the top with glandular hairs. The leaves are large, 20-35 cm long. They are spear-shaped, their lateral lobes are double-cut, with long pointed lobes of the second... ... Forest herbaceous plants
Image of 12 aster inflorescences ... Wikipedia
Angiosperms (Magnoliophyta, or Angiospermae), a division of higher plants that have flowers. There are over 400 families, more than 12,000 genera and probably at least 235,000 species. According to the number of species of C. r. significantly superior to all others... Great Soviet Encyclopedia
Family Compositae (Asteraceae or Compositae). This family is considered the most significant among dicotyledonous plant species. The plant of the Asteraceae family can be found everywhere. Representatives of this family range from 1150 to 1300 genera and more than 20,000 species. In general, wherever there are species of complex plants, you can find representatives of this family.
The Asteraceae family includes trees, shrubs, subshrubs and herbs. These include oilseeds, vegetables, ornamental crops, medicinal crops, and weeds.
Representatives of the family have the following flower formula: * Ca(0, fused) Co(5) A (5) G(2).
A fairly well-known herbaceous plant is “daisies”. They smell nice and belong to several genera that are close to each other. This is also a medicinal plant, or peeled, which is used for a variety of diseases, for example, from the throat, colds, stomach diseases, etc. In the basket of daisies, the middle tubular flowers are yellow, and the reed flowers are white.
The signs are quite recognizable. For example, this family has a special inflorescence - a basket. Its basis is the common receptacle, or the enlarged inflorescence bed. The flower is located on the base. The flowers fit tightly to each other.
The common receptacle is surrounded on the outer side by an involucre. These are the upper leaves, which are significantly or not very modified. The wrapper is needed to protect the flower. There are 1-2 or several rows in which the leaves or involucre leaves are arranged. If Asteraceae grow wild, their baskets are usually small. Their diameter is only 1 or several cm. However, the baskets can also have a larger diameter - up to 10-15 cm. The annual sunflower generally reaches 60 cm in diameter.
But, for example, most wormwoods are distinguished by the presence of rather small baskets - 2-4 mm in height and width.
The general receptacle of such plants is usually flat, but it can also be convex, concave, cone-shaped, etc. The surface of the receptacle can be covered with hairs, bristles or films. The hairs are most often of trichome origin, and the remaining such elements are transformed bracts.
The basket contains a certain number of flowers, the number of which depends on the length of the receptacle.
The size of flowers in plants of the Asteraceae family is traditionally small. The calyx has the appearance of a tuft, which in some cases is called pappus or fly.
This part includes many hairs, bristles, awns, or the pappus is only a membranous rim (crown). Some plants have no tuft at all, and in this case the flower does not have a calyx. Scales, which are the rudiments of a lobed calyx, can be seen in the most primitive plants of this family.
The corolla is fused-petalled with a variety of shapes. The stamens are attached to the corolla tube. Usually there are five. The gynoecium contains two carpels with a style with two branches or stigmatic lobes at its end. If the flowers are sterile, then the style may be indivisible.
The ovary is unilocular, inferior, located near the base. Usually has 1 or 2 ovules, which are located on the funiculus (seed carrier).
The fruit is an achene. The pericarp usually has a certain density. The fruit is indehiscent and single-seeded.
Most often, Asteraceae plant species have bisexual flowers. But the basket does not always contain only fertile and bisexual flowers. Basically, the basket also contains female (fertile) and sterile (male) unisexual flowers. There are also sterile ones, where the gynoecium and androecium are reduced.
Baskets can be homogamous or heterogamous. In the center there are tubular bisexual flowers. Female and reed flowers are located along the periphery of the basket. The heterogamous variety of the basket can be equipped with other varieties of flowers with different sexes and structures.
The leaves vary depending on the plant species. But the leaves are usually distinguished by their alternate arrangement, but the opposite arrangement also occurs. Shapes and sizes come in a wide variety. The venation is generally pinnate. Leaves may be pubescent. Many plants also have spines.
Among the Compositae there is a huge number of annual or perennial herbs. They come in small and very large sizes. But there are also shrubs and subshrubs. Shrubs usually do not grow higher than 8 meters, usually ranging from one to five meters. Trees are also among the Asteraceae. But mostly they do not reach high growth.
You can also see rosette trees, in which the leaves are at the top in the form of a rosette or a bunch. The trunk itself usually has no branches.
A large number of Asteraceae have a cushion-shaped form. Among them, in New Zealand, it is easy to find Haastia pilcharidae and Raulia unusual in stones, since the light pubescence is easy to see from afar.
The Asteraceae family belongs to the class of dicotyledonous plants, is one of the largest, and includes more than 30 thousand species. This family is also called asteraceae. Mostly Asteraceae are herbs; trees and shrubs are rare. Typical representatives of the Asteraceae family in our area are asters, dandelions, chamomile, sunflowers, and dahlias. Among the Asteraceae, there are not many plants of economic importance (sunflower, Jerusalem artichoke). However, there are quite a few plants that have decorative (dahlias, asters) and medicinal value (chamomile, chicory).
A characteristic feature of Asteraceae is the presence basket inflorescences. This inflorescence is often mistaken for a single flower. In fact, individual flowers of Asteraceae are small. In the basket they sit close to each other on a common overgrown relatively flat receptacle. On the outside, the basket is usually surrounded by a wrapper of leaves; this wrapper performs a protective function.
Flowers located in the same inflorescence may have the same structure, or they may be of two different types. It depends on the type of asteraceous plant. Most often, reed, tubular, funnel-shaped flowers are found.
A typical flower of the family Asteraceae (namely a small flower, not an inflorescence) has a double perianth, but the sepals of the calyx are reduced or modified into setae or pappus-forming hairs. The corolla consists of five petals fused into a tube. Five stamens grow together around the style with their anthers. One pistil, one ovule inside the ovary. The fruit, an achene, develops from the ovary.
The types of flowers included in the inflorescence are distinguished mainly by the structure of their corolla. U reed flowers the lower part of the petals grows together into a tube, and the upper part grows together into a kind of tongue located on one side of the flower. That is, the flower does not have radial symmetry. For example, the dandelion basket consists of reed flowers. Its stigma is bilobed. The petals of the calyx are modified into hairs. From such flowers the fruits of the achene with a tuft of hairs (volatile) develop.
Unlike reed ones, tubular flowers have radial symmetry. The lower parts of their petals grow together into a tube, but the upper parts do not grow together. These are the flowers found in the baskets of thistle. Its fruits are achenes with a tuft, also distributed by the wind, like the flying fruits of the dandelion.
Many members of the Asteraceae family have two types of flowers in the basket. For example, a blue cornflower has tubular flowers in the center of the basket; funnel-shaped flowers. The corolla of funnel-shaped flowers is similar to the corolla of tubular flowers, but on one side the petals are larger. Therefore, the flower does not have radial symmetry; it looks like a slightly twisted funnel. In field cornflower, the funnel-shaped flowers in the inflorescence are larger and serve only to attract insects. They have neither stamens nor pistils.
Blue cornflower inflorescence. Funnel-shaped flowers grow along the edge of the inflorescence. Chamomile officinalis is an annual plant. There are two types of flowers in the basket: tubular yellow in the middle, reed white at the edges. Young baskets have medicinal properties. They contain many essential oils that are useful for various human diseases.
meadow cornflower has purple rather than blue flowers. However, like other cornflowers, there are tubular flowers in the center of the basket, and funnel-shaped flowers at the edges.
U tansy small baskets of tubular flowers are collected in complex inflorescences.
Sunflower is a valuable economic crop. This is an annual plant with a huge basket-shaped inflorescence, covered with involucre leaves from below. The number of flowers in a basket can reach 1000. In the middle there are tubular flowers, along the edge there are bright yellow asexual reed flowers that attract insects.
The sunflower fruit is an achene with a dense pericarp.
Sunflowers were introduced to Europe from Mexico in the 16th century. Its economic value was discovered much later. Sunflower seeds contain a lot of oils (like the seeds of most Asteraceae), which are used in food, livestock feed, and for making varnishes and even soap.
The Latin name is compositae (asteraceae).
Class dicotyledonous.
Description. The Asteraceae family is considered the largest of all dicotyledonous plant families and plays an important role in the plant cover of the planet. More than 20,000 species include mostly annual and perennial herbaceous plants, which vary in size from very large (sunflower) to very tiny. Shrubs with a height of 1 to 3 m (sometimes up to 8 m) and low trees are less common. As an exception, the family includes: petiolate scalesia, which reaches 20 meters in height and forms huge forests on the Galapagos Islands, as well as brachylena merana, growing in Madagascar, up to 40 meters high and almost 1 meter thick, with rot-resistant wood.
The main distinguishing characteristics of Asteraceae.
Some plants of the Asteraceae family have a unique compass property. At midday, in order to protect themselves from overheating, they turn their leaves with their edges towards the sun's rays falling on them. In this case, one wide side of the leaf blade is always facing east, the other - to the west, and the intensity of photosynthesis does not decrease. Compass aster plants usually live in open areas. The most famous of them are wild lettuce, widespread in Europe and Asia, and North American lobed silphium.
The Aster family includes many economically important plants:
Some are considered harmful weeds: thistle, thistle, burdock, ragweed, bitterweed, cocklebur, cornflower, yarrow, etc.
Asteraceae flowers are an integral part of the inflorescence - the basket, which at first glance is perceived as one flower. They are usually dioecious or bisexual, sometimes sterile. Based on the symmetry and nature of petal fusion, five types of flowers are distinguished:
In some species, the baskets may consist only of tubular flowers or flowers of two types: tubular in the center, and funnel-shaped or false-ligulate along the edge. Others have only reed ones. Often the flowers in the basket also differ in their sex ratio. The anthers open with cracks into the tube, where a lot of pollen accumulates. The fruit of the Compositae is a single-locular, non-dehiscent achene with a woody or leathery shell, sometimes equipped with a volatile.
Leaves in plants of the Asteraceae family, they are mainly alternate with different types of pinnate venation, less often opposite with purely parallel or parallel-arc venation. Their shape, size and degree of plate dissection vary greatly among different species. The leaves of the leafless baccharis are so tiny (only a few millimeters) that the function of photosynthesis is performed by twig-like stems, and the leaves of the Japanese butterbur reach a length of about 2 meters. Some American vines of the genus Mutisia can boast the most original form of leaf blade.
Many representatives of Asteraceae are characterized by pubescence. Thick down is especially pronounced in species growing in conditions of sudden changes in temperature or constant dryness. The hairs of the fur coat are quite diverse: soft and hard, single- and multicellular, straight or sinuous, unbranched (simple) and bifid, stellate, etc.
Root system in most species of the Asteraceae family it is represented by a well-developed taproot, which is often tuberously thickened (burdock). Many plants also have developed retracting roots, and some have fungal roots.
Spreading. Compositae plants live in almost every corner of the planet where the existence of higher plants is possible. In America, Central Asia and southern Europe they are distributed in significant numbers, and in the northern direction the number of their species noticeably decreases. Some species have taken root in the tundra, among alpine snows and even on barren sands. In the highlands of tropical America and Africa, original rosette asters are found. In deserts you can see heavily pubescent, shrubby or cushion-shaped, thorny and almost leafless plants with flattened green stems.
Reproduction. The vast majority of plants in the Asteraceae family are insect pollinated. They have inconspicuous tubular flowers in the center of the basket surrounded by bright white, yellow, orange-golden or red large flowers, clearly visible from a great distance. They are often sterile and perform only a signaling function. Other asteraceae with inconspicuous inflorescences attract insects with nectar released at the base of the style and pollen. The main pollinators are bees, bumblebees and wasps, and in some species of the genus Mutisia - birds. Some members of the family (for example, dandelion) produce fruits without fertilization.
Class dicotyledonous. Family Compositae (Asteraceae)
What do they have in common?familiesAsteraceae and the family Pasaceaelinen? Why are these plants soWhat are their names and how many of them are there on Earth?
Among the wild-growing Compositaenyh most famous and beloved - vaSilk and chamomile. But can you do them?distinguish? Are all cornflowers blue?Are we really guessing with daisies?
Let's answer these questions,and also find out which plantsbelong to this family.
General characteristics of the family Compositae. In total there is on Earth250 thousand species of flowering plants,of which 25 thousand species are Compositaeny, which amount to 1000 births.Asteraceae can be seen everywhere:in forests and steppes, in tundra and desert,in the tropics and mountains.
The first of them to bloom in early springmelts coltsfoot. GoldenOdu vanchiki signal the startsummer, but most of them are asteraceaenykh begins to bloom in midsummerand blooms until late autumn. In ouron the edges they are all herbaceous plantsnia, even sunflower, height up to4 m, is grass. In the tropics there isand shrubby forms.
All Asteraceae have one common feature:inflorescence - basket , by which they are easy to recognize. Although the size of the basket can be 30 cm for sunflowers, and several millimeters forwormwood or salad. Large, bright inflorescences are pollinated by insects, while nondescript ones are pollinated by the wind. This inflorescence is often confused with a large flower (even insects make mistakes - they mistake the inflorescence for one flower). Contributes to thiswrapper - the leaves that surround the basket are reminiscent of sepals. And also the fact that in the basket itself the flowers can be different in shape.
U reed Flower petals grow together into a tube, leaving the upper part free - in the form of a tongue with 5 teeth. These are dandelion flowers or marginal chamomile flowers. In the center of the chamomile are tubular flowers. A tubular flower has petals fused into a tube with a five-toothed edge. There are alsofunnel-shaped flowers. They look like a wide funnel with teeth. In cornflower, funnel-shaped flowers do not have stamens and pistils, but serve to attract insects to the tubular, not so bright, flowers.
Four types of flowers:
| reed(dandelion, chicory) | tubular(thistle, inner flowers of cornflower) |
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| funnel-shaped, do not have stamens and pistils (outer cornflower flowers) | pseudolingulate, have 3 fused petals, can be asexual (at the edges of the inflorescence of chamomile, sunflower) |
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However, all flowers have a double perianth with a peculiar calyx consisting of a tuft of hairs or scales. The corolla consists of 5 fused petals. There are also 5 stamens, fused with their anthers. There is one pistil (if the flower is bisexual) with a bilobed stigma. The fruit of all Asteraceae isachene , often with a tuft of hairs - a flying fruit.
Wild plants of the Asteraceae family
Mayweed - an annual or biennial plant with an erect stem and dissected leaves. In the basket at the edges there are white reed flowers, which can be mistaken for petals that attract insects. These flowers are unisexual, female, with only 3 teeth at the top, not 5, they are called false-ligulate. In the middle there are yellow tubular flowers with 5 teeth. There is no calyx, 5 stamens are fused with anthers, one pistil. The fruit is an achene. Inodorous chamomile does not have white outer flowers.
Basketschamomile officinalis used in the treatment of gastrointestinal diseases and for rinsing. All daisies are annual weeds.
A plant that is commonly called chamomile iscornflower . Perennial, with whole, rather than dissected, serrated leaves and large single baskets. Common in meadows and often grown as an ornamental plant.
It also has medicinal value yarrow - It is used as a gastric and hemostatic agent. Some yarrows are grown as ornamental plants. Yarrow gets its name from its heavily dissected leaves.
U blue cornflower marginal flowers are funnel-shaped, asexual. It is an annual, crop weed and ornamental plant. The petals are used as an eye remedy. Cornflowers come not only blue, but also pink, yellow and white.
Dalmatian chamomile (pyrethrum), which can be found in our gardens and flower beds, is a good insecticide.
Wormwood , a weed, is a good stomach remedy.
Roots chicory used as surrogate coffee. It is a weed and an ornamental plant.
Field thistle And sow thistle pink - this is the same type of perennial dioecious weed with a long rhizome that easily produces root shoots. The basket consists only of tubular flowers.
Thistle, a weed of poorly cultivated fields, has the same inflorescences.Thistle - a good honey plant.
Field sow thistle with yellow baskets of reed flowers - a malicious weed of the Asteraceae.
Dandelion officinalis with baskets of only reed flowers, it is also a weed used in medicine. Despite the bitter taste, it is edible, and young scalded leaves are suitable for salad.
Cultivated plants of the Compositae family. Among the plants of this family there are not only medicinal and weeds, but also ornamental, food, fodder, and industrial plants. Therefore, much attention is paid to the study of the family.
The most important food plant issunflower . Its best domestic varieties were bred by Academician V. S. Pustovoit. The achenes contain up to 57% oil. The oil is used for food, as well as in soap making and paint and varnish production. The cake, threshed baskets and silage are used to feed livestock. So the whole plant is used.
The homeland of sunflower is South America. It was brought to Europe by the Spaniards in 1510. Sunflower came to Russia from Holland and was first used as an ornamental and gnawing plant. But in 1829, the serf peasant of the Voronezh province D.S. Bokarev received oil from sunflower seeds for the first time. This crop immediately began to be widely cultivated in Russia, and in the middle of the 19th century it was exported from Russia to the USA and Canada.
Various organs of Asteraceae are used for food. Leaves salad, root tubers Jerusalem artichoke(ground pear), juicy wrapper scalesartichoke . U salsify, for example, the juicy white roots taste like oysters.
There are surprisingly diverse ornamental asteraceae that reign in flower beds in the second half of summer and autumn. The queen among them is chrysanthemum, one of the symbols of Japan. Good also dahlias Asteraceae are the largest family of flowering plants. Among them there are many medicinal, ornamental, food, and also weed plants. Sunflower, the leading oilseed crop, has important nutritional value. Asteraceae are herbaceous plants. Their most characteristic feature is the inflorescence basket. As a rule, Asteraceae have five-membered flowers, the fruit is an achene, sometimes with a tuft of hairs. Asteraceae have a fused corolla of five petals
