Evolution of Plants in brief

Plants are the multicellular living organisms and they carry out the process of photosynthesis. Plants are observed to have evolved from the group of algae called, "green algae". The photosynthetic pigments that are present in the plant groups are chlorophyll a, chlorophyll b and beta carotene. The plants store the food materials in the form of amylose. Plants are unique in having cellulose as one of the structural components of their cells. The haploid gametophyte generation of the plant alternates with diploid sporophyte generation. The life-cycle of plants includes diploid and multicellular spore forming plant called sporophyte, which gives rise to the haploid spores through a type of cell division called as meiosis. These haploid spores’ undergo mitosis and give rise to a haploid and multicellular plant called as gametophyte. The gametophyte produces again gametes that are used up to the formation of sporophyte. In the adult plants, the diploid multicellular embryo gets nourished inside the haploid multicellular tissue. This type of embryo varies from the algal embryo, which remains separate from the haploid gametophyte tissue.

Plants are classified majorly depending on the presence of vascular system and on its absence. The vascular system is used for the water and mineral transportation from the soil to the plant parts. The plants which do not have vascular system are termed as bryophytes. They include mosses and liverworts. They can live most of the time in the damp locations. The plants having vascular system are termed as tracheophytes. In the tracheophytes, seed forming and seed less plants exist. Seedless plants that have vascular system include ferns, club mosses and horsetails. Among these, ferns occupy large percentage. The seed bearing plants are called as gymnosperms and angiosperms. They have certain features in common like extensive root system, reproductive organs that consist of gametophyte seeds protected inside the sporophyte and vascular system that consists of xylem and phloem.

Gymnosperms are the seed bearing plants. Some of them have their seeds exposed and in some, the seeds are naked. Coniferous plants are grouped under this category. Angiosperms are flowering plants and they are classified further into monocotyledons and dicotyledons. The monocots have only one cotyledon while the dicots have two. The major distinction that can be observed when one looks at the monocots and dicots is that monocots have parallel venation on the leaves while dicots have reticulate. The parts of the flower having multiples of three in monocots and multiples of four in dicots is another feature of distinction between them.

The land plants slowly started to adapt to the habitat where they are living. Based on that, they are known as mesophytes, xerophytes, lithophytes, hydrophytes and so on. So, depending on the habitat and environment, the plants are adapted and evolved accordingly.