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Types of dehiscence

By Seolncr Subscribe to RSS | May 8th 2012 | Views:
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In Botany , the floral diagram is a graphical representation of the arrangement of floral parts ( sepals , petals , anthers and carpels ) and the management of different whorls , in a cross section of the flower . Each whorl ( calyx , corolla , androecium and gynoecium ) is represented, by convention, with a concentric circle around the gynoecium, indicated by a cut to the height of the ovary . The sepals are drawn as white lunes, lunes petals as black or sometimes colored. The stamens are symbolized by cross sections of anthers, and gynoecium is represented in the center of the diagram by a cross section of ovary. Generally the pieces of a whorl alternating with pieces of previous whorl. The yarns may be opposed or alternate with respect to the petals. The welding between the parts of each whorl or opposite whorls, is indicated by dotted lines. Using these diagrams is well expressed the floral structure, it follows from its symmetry, the number of members in each whorl, and in the case of the sepals and petals, the pre-flowering, its welded or independence of the androecium the relative position of the stamens with respect to the perianth, the concrescence or separating them, their union or autonomy from the corolla and introrsa or extrorsa position of the anthers. The gynoecium, you can see the number of carpels and cavities in the ovary and placentation of the ovules. 1 2 The following is the floral diagram and description of it for some families of flowering plants.

The flowers are hermaphrodite , actinomorphic . The perianths consists of 6 tepals arranged in two whorls trimers, are separated and free of the other floral parts. The androecium has 6 stamens arranged in 2 whorls also trimers, the strands are separated and free of the other floral parts. The androecium is diplostémono (ie the outer whorl of stamens is opposite the outer tepals and the inner loop is opposite the inner tepals). The gynoecium is ovarian súpero and consists of 3 carpels connate, is trilocular. The eggs have axillary placentation .

For other uses of this term, see dehiscence (medicine) .

In botany , the term dehiscence means the spontaneous opening of a plant structure, once arrival maturity to release its contents.

Referred to many types of fruit , means the time at which they are opened to release the seeds and disperse , so we talk about loculicidal dehiscence when the fruit is opened by the midrib of the carpels .

Referring to anthers , is when they are opened, releasing the pollen .

In the lower floors, is also called the opening dehiscence of sporangia , releasing sexual or asexual spores.

Dehiscence is the last function of the anther , which causes the release of the grains of pollen . This process is exactly coordinadao with pollen differentiation, floral development and openness.

The wall of the anther splits longitudinally, producing as an indentation between the locules of each theca .

The stomium is the region where the anther dehiscence occurs. Necróptica degeneration of cells of the stomium and the septum is part of the programmed cycle of development and cell death. The expansion of the layers of endoteciales and lignification of cell walls are essential to endoteciales dehiscence.

Depending on the shape of opening of the anther can be classified as:

Longitudinal dehiscence: When the anther opens lengthwise, ie from top to bottom or vice versa.

Dehiscence transverse: When the anther is opened transversely.

Dehiscence apical: one in which it opens a pore apical leaves through which pollen.

According to the direction in which the filaments make the process of dehiscence, can be:

Dehiscence introsa: That which occurs towards the center of the flower , this facilitates self-pollination .

Dehiscence extrorsa: one that occurs out of the flower, which requires a great deal to the pollination cross.

If fruits are classified by the type of development of the pericarp, can esxistir two classes: the dry and fleshy.

The dehisencia occurs only in nuts, and the type of placentation and fertilization that took the fruit, different types of dehiscence:

Sutural dehiscence twofold: the carpel opening by the dorsal nerve and between nerves in placental and vegetables .

Sutural dehiscence simple: the carpel opens placental nerves only.

Example: follicles and Polifoliculos .

Placentigrafa Dehiscence: opening of the carpel is made ??up of two lines parallel to the placenta.

Example: Siliqua and silicula .

Dehiscenia loculicidal.

Placentifraga dehiscence.

Septicidal dehiscence.

Septifraga dehiscence.

Dehisencia poricida.

Valvular dehiscence.

A fruit that develops a gynoecium composed of carpels merged, that after fertilization grows becoming silique after maturation seminal dehiscence takes place, and the shells come off the septum freeing the seeds plant.

This process is similar to the anthers dehisced and the region is torn (dehiscence zone) runs entirely along the fruit between the valves and the replum (external septum).

At maturity, the dehiscence zone is effectively an unlignified layer between a region of lignified cells in the valve and the replum. Expulsion occurs due to the combination of loss of cell walls in the dehiscence zone and tension set by differential mechanical properties of the cells in the silique drying.

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