Foliar layout, or phyllotaxis, is a kindscheme on which the leaves are located on the stem of the plant. Even at first glance it can be determined that they never grow in a chaotic manner, and there are important reasons for this.
Light access
Why leaves do not grow there, "wherever they like"?The reason, of course, is in the lighting. As a result of evolution, several types of leaf arrangement have been formed, which provide each sheet with the maximum access of light. So, the leaves of the same plant do not compete with each other. As a rule, the pattern of leaves is associated with the apex of the shoot, reflecting its symmetry along the radius. In describing leaf location in morphology, it is usually based on the number of leaves that depart from a single node.
Scheme
The leaves can be located in three mainto schemes which are called so: next, whorled and opposite. It is simple to remember: at the next - one sheet from one node, at the opposite - two leaves, and at whorled - three or more (for example, elodea has more than three leaves). The latter is one of the most uncommon types of arrangement characteristic of herbaceous plants. The leaves grow from a single node, forming a so-called verticil - a ring around the stem. This pattern is typical of herbaceous plants, for example, northern northern bedcloth, lupine clover and raven four-leaf eye.
In a separate type of phyllotaxis can be includedsocket, which should not be confused with whorled. The rosette is formed by leaves with a different leaf location, in case the stem is shortened. This can be observed in plants such as agave, chlorophytum, saberjack and others.
In a row
Листорасположение очередное, или, как его еще Called, spiral, involves the growth of leaves, one for each node. To understand and remember this species, simply look at the branch of an oak or birch. The leaves are arranged on the stem alternately, in a spiral.
As a rule, in the lower forms the arrangement of leaves is opposite, and in the more highly developed plants - the next.
Heredity
In adult shoots leaf location, the nextit or another type is determined by the order of origin of leaf primordium. These are leafy plant beginnings. It happens that any type of phyllotaxis is characteristic of all plants of one family. However, leaf location may change as the shoot grows. Petioles, moreover, can be bent in various ways, therefore leaf plates can also change their position. This is due to the fact that the leaves are constantly in search of the best position where they will receive the maximum amount of light.
Ultimately, the distance between largeleaves are filled with smaller ones, without shading each other, forming a solid leaf cover. The phenomenon has received the name "sheet mosaic". It allows the plant to make the most of all the sunlight that can get on the leaves. This feature is characteristic of all types of phyllotaxis, and this is not an exception, another leaf arrangement. Examples will be given below.
Examples and properties
Layout is the next on our planethas a lot of plants. Almost all deciduous tree species growing in Central Russia have another phyllotaxis, and not only the leaves, but also the branches. These are oaks, birches, aspens, among garden trees - plums, apples and cherries, and bushes - currants, gooseberries, black chokeberry.
Interestingly, there are two exceptions to this.list. The ash-tree property has the opposite arrangement. The same phyllotaxis has Norway maple, popularly called Canadian, while the American maple (ash) has another leaf arrangement.
