Keyword: Flower bud
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The flower bud of cultivated grapevine is a so-called flower hermaphrodite , meaning it contains the male and female sexual organs in a single Bloom combined. The male sexual organs are the pollen-producing stamens or stamens (stamens, stamens Mz), which consist of the rod-shaped filaments (filament) and seated at the head of yellow anthers (anthers). The totality of all stamens of a flower are the androecium. An anther contains four pollen sacs in which pollen grains are formed with the haploid (n = 19) male gametes (fertilization) hormones. In the flowering vines surrounded five of these free-standing circle of stamens, the female sexual organ, the ovary (ovary). This consists of two fused carpels (carpels), which contain two compartments inside with ovules. Therefore, the vine is one of the angiosperms, or flowering plants (see also under Vines classification ).
The ovary is at its peak in the style of which terminates in the stigma (stigma). The disk-shaped scar is a spongy tissue that separates sticky secretions. At the base of the stamens and the ovary, there are five nectaries (nectar glands) that are fused into a ring (disk or cup). Five poorly developed sepals (sepals) and five to a cap-knit green petals (petals) cover in the form of an inverted calyx, the stamens and the ovary. These yellow-green perianth (cap, small cap, Perianthium) at the start of the bloom dropped, then can be done pollination.
If the fertilized by pollen of the same vine (for example Veltliner pollen on stigma Veltliner), one speaks of a Selfing , which means self-fertilization. Are pollen grains of different varieties of vines, and also, that different genotypes involved (for example Silvanerpollen scar on Riesling) is referred to as cross-pollination. For the fruit set and berry development, it is largely irrelevant whether the seed was self-or cross-pollinated. So even if pollinated, for example, a Riesling from a scar Silvanersamen, developed a Riesling grape. The pollination was carried in this case natural hybrid of the two grape varieties is so only potentially present in the embryo of the grape seeds and sowing and germination was only at the core of this to take effect. Elapse between pollination and fertilization of the egg cells of the scar two to three days depending on the ambient temperature. The pollen begin to germinate on the stigma, a pollen tube grows through the style and penetrates to the maternal ovules in the ovary.
There, the haploid nucleus (haploid = simple set of chromosomes, n = 19) of the male gametes released into the egg cells of there with the haploid maternal set of chromosomes of the DNA double (n = 19) for re diploid nucleus (diploid = set of chromosomes: 2n = 38) of the now sexually fertilized ovum fuses. This is the actual fertilization process. Subsequently, a formation of tissue (placenta) from the ovules (ovaries) the seeds (berry seeds) with the embryo therein. The seed development stimulates hormones on the development of the berry tissue and thus the set fruit . The sequence is formed by the carpels of the ovary a wine-berry, which can include fertilization with complete up to four cores. The woody stem of the flower bud is the pedicels and bearing the single berry. See also Bloom , Molecular genetics , Vine and Breeding .