We will talk about one of the most numerous families among dicotyledonous plants - aster (composite). Without noticing it, we encounter its representatives almost daily - in everyday life, in cooking, and just on the street. Flowers of the aster family are perhaps the most common in our flower beds and gardens, and no kitchen can do without sunflower oil.
Aster family: general characteristics
The family includes a very large number of genera, it is rather difficult to give an exact figure, it ranges from 1100 to 1300, and there are more than 20,000 varieties. Most of the plants are pollinated by insects. The distribution area is quite wide, representatives of this family are found in all climatic zones: from hot and humid tropics to cold tundra, high in the mountains and on the coast of the seas. They grow on fertile chernozems and desert sands. A large number of species provided asters with a wide range ofeconomic application in human life.
A distinctive feature of all plants that include the Asteraceae family is a complex inflorescence - a basket, which consists of many small and inconspicuous flowers, but together they make up a very impressive picture.
Flower structure
The name of the inflorescence seems to speak for itself: a basket, that is, a certain container in which something is folded. Capacity is a pedicel extended at the end, it can be flat, convex or concave. Just on it are numerous small flowers. And around all this is surrounded by one or more rows of bracts. All flowers of the family are divided into five types:
- Tubular, most often hermaphrodite and much less often same-sex. They are shaped like a tube that expands at the end or has a bend.
- False-lingual flowers - they are formed by splicing three petals and have the same number of cloves located on the upper edge.
- Reed - the corolla has the shape of a shortened tube, from which the petals grow together. As a rule, they have five stamens and one pistil.
- Funnel-shaped - flowers of an asymmetric shape, asexual, corolla in the form of a long tube strongly expanded at the end (funnel).
- Two-lipped flowers - the corolla tube is long enough, and two tongues (lips) are bent from it. Can be bisexual or same-sex.
If we take the same sunflower as an example, then we are all used to perceiving it assingle lush and beautiful flower. And this is absolutely wrong from the point of view of botany. Since in reality it is an inflorescence that contains more than 1000 individual small flowers (tubular), and wide and bright orange or yellow petals are reed flowers. An amazingly complex and delicate organization, thought out by nature to the smallest detail.
Representatives of the family have the following flower formula:
Ca(0, fused) Co(5) A (5) G(2).
It is typical for the entire aster family. The flower formula is deciphered as follows: the flowers are bisexual, have several planes of symmetry, a calyx, a corolla of five petals, 5 stamens, two pistils, an ovary above them.
Structure of leaves and roots
About the structure of the leaves can only be said in general terms, since this is a fairly large group of plants, represented by various life forms. Sunflower, burdock, thistle, asters and zinnias, Jerusalem artichoke, tree forms, yarrow, gerberas and many other species - all this is the aster family. The general characteristic is that the arrangement of the leaves is usually alternate, but may also be opposite. The sizes, and even more so the shape, vary in a very wide range from a few millimeters to 2-3 meters. Venation in members of the family is most often pinnate. The leaves may be pubescent, the degree of expression varies, many plants have spines.
The root is quite well developed and in most plantshas a core structure (a well-developed main root and many adventitious ones). For example, it is enough to recall a typical representative of the family - medicinal dandelion, many are familiar with it and its root system. There may also be modifications with thickenings resembling a tuber, for example, burdock.
What fruits do plants of the aster family have?
Asteraceae (compositae) have an achene fruit. It is dry, the seed contains one. The pericarp is leathery and does not break when ripe. The formation of various hairs, protrusions, and peculiar hooks on the achene is widespread, which in turn contribute to the spread of seeds in the wind (in dandelion, wormwood), with animals or on people's clothes (string, burdock).
Asteraceae life form
Life forms are represented almost in full, and this is primarily due to the huge distribution area, but still aster (composite) are mostly herbaceous plants (annual or perennial). Sizes vary widely - from very tiny representatives to giants several meters high.
Many species are shrubs or shrubs of quite impressive size (up to 5-8 meters in height). For example, the swamp melampodium, which is native to the wet, marshy forests of Louisiana in the United States.
The Asteraceae family also has representatives among trees, although they are all inhabitants of the southern regions. For example, scalesia in the Galapagos Islands, which can reach20 meters in height, but it is endemic, and it is no longer found in any corner of the planet. Or plants of the genus Brachilena from South Africa. Giant trees that have strong enough wood that is resistant to decay, for which they are highly valued.
In the alpine meadows of New Zealand, the downy haatsia forms entire thickets. This is a tree-like form that covers fairly large areas with a thick carpet up to half a meter high (one plant can grow up to two meters in diameter).
Found among the Compositae lianas (mikania, mutisia), succulents and even such a rare life form as tumbleweeds (spreading cornflower, dwarf asteriscus).
Traditionally, the entire Aster family is divided into two subfamilies: tubular and reed.
Subfamily Asteraceae (Tubular)
The overwhelming majority of colors are tubular. This group of plants has more than a thousand genera and more than twenty tribes (taxonomic rank in botany, which is lower in value than a family, but higher than a genus). For example, the most famous are aster, calendula, sunflower, navel, marigold and others.
Subfamily chicory (or lettuce)
Their second name is reed, unlike the previous family, they contain only seven tribes, and the number of genera is about two hundred - this is a small part of the total number of plants included in the Asteraceae family. Representatives of chicory grow on almost all continents, in our country the most famous species is chicorycommon, notable for bright blue flowers and common as a weed. But nevertheless, the plant is a good honey plant, and in cooking the root is used to make coffee.
Aster family: nutritional value
The use of plants of this family in cooking has been popular for a long time, the most famous example is oilseed sunflower. His homeland is North America. It has successfully acclimatized in our area, now sunflower is grown on an industrial scale. The main product of it is, of course, sunflower oil. But in addition, they receive seeds, lard (a solid fat used to make margarine and soap), and waste products are used as animal feed.
Another bright and edible, but, unfortunately, we do not have a growing representative of the family - the artichoke (pictured). Traditionally, it is considered a vegetable, but in fact it is an unopened bud. As an independent dish or side dish, it is widely distributed in the Mediterranean countries and in America.
The Jerusalem artichoke is famous for its taste, cultivated not only as food, but also as a technical and fodder plant.
Decorative and medicinal value
The aster family (photo) has long been famous for its decorative and flowering species.
Breeders have bred an incalculable number of varieties of garden flowers. Everyone is familiar with chrysanthemums and gerberas popular in flower shops. At least once everyone who hasthere are flower beds, grown asters or daisies, zinnias and marigolds, dahlias and ageratums.
Of the medicinal plants, the most popular and useful are: chamomile, arnica yarrow, succession, milk thistle, wormwood, tansy, calendula and many others. Their healing effect on the body has been tested and proven, decoctions or infusions of these herbs are the most valuable homeopathic remedies.
The aster family, whose representatives are known, perhaps, to everyone, gave the world an incredible amount of valuable economic, ornamental, medicinal plants.
