Krytosemennými

Krytosemennými, also known as angiosperms, represent the largest and most diverse group within the plant kingdom. Their defining characteristic is the presence of flowers and fruits, which are adaptations for reproduction and seed dispersal. Flowers, with their often vibrant petals and intricate structures, serve to attract pollinators, such as insects, birds, and bats, facilitating the transfer of pollen. Following successful pollination and fertilization, the ovary of the flower develops into a fruit, which encloses and protects the seeds. This protective casing also aids in the dispersal of seeds, often by animals that consume the fruit.

The life cycle of krytosemennými involves alternation of generations, with a dominant sporophyte generation that is diploid. The male gametophyte produces pollen grains, while the female gametophyte, contained within the ovule, produces the egg cell. Double fertilization is a unique process found in angiosperms, where one sperm cell fuses with the egg to form the embryo, and another sperm cell fuses with the central cell to form the endosperm, a nutrient-rich tissue that nourishes the developing embryo.

Krytosemennými are further divided into two major classes: monocotyledons (monocots) and dicotyledons (dicots). Monocots are characterized by having a single cotyledon (seed leaf) in their embryo, parallel leaf venation, and flower parts typically in multiples of three. Examples include grasses, lilies, and orchids. Dicots, on the other hand, typically have two cotyledons, net-like leaf venation, and flower parts usually in multiples of four or five. This group encompasses a vast array of plants, including roses, oaks, and sunflowers. The evolutionary success of krytosemennými is attributed to their efficient reproductive strategies, diverse adaptations to various environments, and their crucial role in many ecosystems, providing food and habitat for numerous organisms.