Bryophyta

Short after the emerged lands were conquered, plants were classed into: bryophyta, that include hepatics, anthocerote and mosses and vascular plants, i.e. all higher plants.
The structure of bryophyta is very simple and it is made up of individuals that are generally shorter than 20 cm. Bryophyta do not have roots, but they have rhizoids, i.e. long cells or cell filaments, that stick to the substrate. Many bryophyta have a leaf-like structure, made up of few cell layers through which they carry out the photosynthesis. As they have no roots to absorbe the water, they have to take the water from aerial structures, therefore they grow maily in wet and dark areas, or in marshes.
The vascular tissue of bryophytes is not divided into xylem and phloem, therefore liquids flow through central elongated cells . Bryophytes consist of haploid gametophytes, which are the dominant generation. On the top part of some of the leaflets, the antheridia  which produce male germinal cells, and the archegonia which produce egg cells, form. The male gamete swims in the droplets of water, pushed by two flagella. The sporophyte grows on the gametophyte, and in the capsule of a mature sporophyte meiosis takes place. When the capsule opens, around its opening  is a ring of teeth. The teeth remain bent towards the spores that have just formed when the atmosphere is dry. When, instead, there is humidity, the teeth straighten out due to hygroscopy, helping the dispersion of the spores in the air, which find optimum conditions for germination.

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