Obstacles Overcome by Land Plants
The four major groups of plants are bryophytes, pteridophytes, gymnosperms, and angiosperms. These four were said to have evolved from the aquatic plant, charophycean algae. Therefore, terrestrial plants have adapted some characteristics in order to survive on land: body support, transport of materials, and fertilization.
The bryophytes, which are known to be the first to evolve from the charophycean, lack the structural support such as the rigid cell walls. That is why they are short and are slightly bent instead of tall and rigid. However, they were still able to survive even without rigidity. Pteridophytes, gymnosperms, and angiosperms, on the other hand, do have the structural support. Few pteridophytes grow more than a meter tall; however, gymnosperms and angiosperms are the most well developed adaptations for structural support.
The transport of materials such as minerals and water to each plant cell is another obstacle. The charophycean can transport directly from their environment because they are in an aquatic environment. Therefore, these aquatic plants do not need roots, structural support, and vascular tissues to take in these minerals and water. Land plants, however, are not surrounded by water. That is why this is another obstacle they have to face. Terrestrial plants must get these materials from the soil. Bryophytes have rhizoids that do not help absorb water and mineral absorption. Bryophytes use diffusion to obtain water and minerals. Pteridophytes, gymnosperms, and angiosperms, on the other hand, have vascular tissues to conduct water and minerals from the soil. Plant structures differentiated also resulted from this: leaf cells that make food, stem and branch cells for support, and root cells to transport nutrients and water from the soil. All these helped to support plants to survive on land.
... Plant cells have a cell wall, where animal cells do not. The cell wall is not living. It has semi-permeable cell membranes, which allows water ... to enter or leave, by osmosis. When plant cells are put into distilled water they ... will swell up, but they do not burst. Plant cells also have ...
Another challenge is gamete fusion, fertilization. In an aquatic environment, flagellated sperm are dispersed in the water and they swim to the eggs. This can only happen in land if some plants live in moist environment. This exactly happens to bryophytes and pteridophytes. However, gymnosperms and angiosperms do not have flagellated sperm. This means they do not live in moist environment. Therefore, the answer is alternation of generations: a sporophyte generation that produces spores and gametophyte generation that produces gametes. For gymnosperms and angiosperms flagellated sperm evolved into pollen grains, eggs are now on scales (gymnosperms) or within the ovaries (angiosperms).
Moreover, instead of water, wind and animals helped their disposals and fertilization.