A regular layout: a description and examples

Linespacing, or phyllotaxis - is a kind of scheme, along which the leaves are located on the stalk of the plant. Even at first glance, it can be determined that they never grow in a chaotic order, and there are important reasons for this.

Access of light

Why do not the leaves grow there, "where do you like"? The reason, of course, is in lighting. As a result of evolution, several types of leaf arrangement have formed, which provide each leaf with maximum light access. Thus, the leaves of the same plant do not compete with each other. As a rule, the regularity of the arrangement of leaves is associated with the apex of the shoot, reflecting its symmetry along the radius. When describing the leaf locations in morphology, they usually rely on the number of leaves that depart from one node.

Scheme

Leaves can be arranged according to three basic schemes, which are called so: the next, whorled and opposite. Remember simply: when the next - one sheet from one node, with opposite - two sheets, and with a whorled - three or more (for example, the Elodea has more than three leaves). The latter is one of the most common types of disposition typical of herbaceous plants. Leaves grow from one node, forming around the stem a so-called whorl-ring. This scheme is typical for herbaceous plants, for example, the northern bedrock, the clover of the lupine and the crow's eye of the four-leaved.

In a separate type of phyllotaxis, you can include an outlet that can not be confused with whorled. The rosette is formed by leaves with different leaf positions, in case the stem is shortened. This can be observed in plants such as agave, chlorophytum, saxifrage and others.

In a row

The leaf pattern next, or, as it is also called, spiral, suggests the growth of leaves one by one for each node. To understand and remember this species, it is enough just to look at the branch of oak or birch. The leaves are arranged on the stalk alternately, spirally.

As a rule, in the lower forms the arrangement of leaves is opposite, and in more highly developed plants - the next.

Heredity

In adult shoots the leaf arrangement, the next one or another type, is determined by the order of origin of leaf primordia. These are leaf rudiments of plants. It happens that any type of phyllotaxis is characteristic of all plants of the same family. However, the leaf arrangement can change during the growth of the shoot. Petioles can also be bent differently, so the 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.

Eventually, the distance between the large leaves is filled with smaller ones, not obscuring each other, forming a continuous sheet cover. The phenomenon was called "leaf mosaic." It allows the plant to make the most of all the sunlight that can reach the leaves. This feature is typical for all types of phyllotaxis, not an exception and the next leaf arrangement. Examples will be given later.

Examples and properties

The leaf pattern next on our planet has many plants. Almost all the deciduous tree species that grow in the middle part of Russia have the next phyllotaxis, and not only the leaves, but also the branches. These are oaks, birches, aspen, among the garden trees - plums, apple trees and cherries, and bushes - currants, gooseberries, chokeberry.

Interestingly, there are two exceptions to this list. The property of the ash-trees has a controversial location. The same phyllotaxis has a maple-leaf maple, popularly called Canadian, but the American maple (ash-tree) has another leaf.