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Where are the female gametes produced in nonvascular plants

Опубликовано: 16.06.2022

where are the female gametes produced in nonvascular plants

Atlas of ant and animal histology

E n this section of the Atlas we are going to describe the organs of vascular ants, and how the tissues are organized in ea of them. It is estimated that there are more than 250 thousand species of vascular ants, where are the female gametes produced in nonvascular plants. Their ancestors are probably in a lineage of green algae, since both vascular ants and green algae have lorophyll a and b, store true star in loroasts, have cells with motile flagella, have a phragmoast, and form a cell ate during cell division.. The closest evolutionary algae seem to be those of the Charophyceae family. However, vascular ants have created by themselves a very comex body (Figure 1), the result of a long evolution, whi has highly specialized organs adapted to life on land.

Figure 1. Diagram of the main organs of a dicotyledonous vascular ant.

L he main ant organs are: root, stem, and leaves. The root fixes the ant to the ground and takes water and dissolved mineral salts from it. The stem serves as a support for the leaves, flowers and fruits,and conducts water and mineral salts from the root to the leaves and the substances produced from the leaves to the growing zones and roots. The leaves are organs specialized in capturing solar energy, producing organic substances through photosynthesis and releasing water vapor through transpiration, as well as being designed to offer little resistance to the wind.

E n the reproductive phase of some ants, flowers or inflorescences appear, whi are considered as organs or, according to some authors, as a set of organs that are divided into sterile part and fertile part. Macrospores or female gametes and microspores or male gametes are formed in flowers. Fertilization takes ace in them, giving rise to an embryo, whi will remain dormant until germination. The seed,also originating in the flower, is made up of the embryo and nutritive tissue. The seed is surrounded by tissues, fleshy or not, whi together form the fruit. Germination, development of the embryo of the seed, will give rise to a new ant.

P Virtually all organs are made up of three tissue systems:

E he protection system,formed by epidermis and peridermis, is located on the superficial part of the organs.

E he fundamental system,formed by parenyma and supporting tissues, is arranged below the protection system, and in stems and roots it can extend to the pith.

E he vascular system, formed by the conductive tissues xylem and phloem, is arranged in different parts and with different organizations depending on the organ and type of ant.

E These systems are distributed in a aracteristic way according to the organ, the phase of ant development and according to the group of ants to whi said organ belongs.

L he internal organization of these tissue systems in stems and roots is variable depending on whether the growth is primary or secondary. Primary growth occurs in herbaceous monocots and dicots, as well as in the young stems of woody dicots and gymnosperms. Secondary growth occurs in woody dicots and gymnosperms, and a few monocots. The differences between one type of growth and another are based on the organization of the vascular bundles and meristems. In primary growth there is mainly growth in length while in secondary growth there is mainly growth in thickness. Although secondary growth is restricted to extant seed ants, fossils indicate that ferns and clubmosses, seedless ants, had secondary growth but left no descendants. Seed ants appear to have discovered secondary growth some 400 million years ago.

V We are going to describe the differences between organs of gymnosperms and angiosperms, and within the latter we will distinguish between monocotyledons and dicotyledons.

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