Bryophytes vs Pterophytes
The first organisms colonized the land 420 million years ago. These were the earliest plants. Plants are eukaryotes and autotrophs. They are well adapted to terrestrial mode of life. Method of nutrition of plants is photosynthesis. Plants are gradually improving adaptations to terrestrial life along with evolution. Classification of plants is related to the adaptations they show to the terrestrial mode of life. According to the modern classifications, kingdom plantae includes five phyla in which the most primitive two phyla are the phylum bryophyta and phylum pterophyta.
Bryophytes
Bryophytes include liverworts and mosses. Bryophytes are the first group of plants that colonized the land. They are not fully adapted to terrestrial life, because their dominant plant is the gametophyte, plant body is not differentiated into roots, true stems or leaves, rhizoids are the main anchorage organs, vascular and mechanical tissues are absent, external water is necessary for fertilization, sporophyte depends totally or partially on the gametophyte etc. But they showed some adaptations for terrestrial life. Reproductive organs are multicellular organs with sterile jackets. Spores are disposed by wind. Bryophytes show heteromorphic alternation of generation in the life cycle as all other plants. Alternation of generation is the alternation of a haploid gametophyte with a diploid sporophyte in the life cycle.
Pterophytes
Pterophytes include ferns. The dominant phase is the sporophytic phase. The sporophyte is independent, diploid and differentiated into roots, stems and leaves. The stem is an underground rhizome, which can tide over unfavorable conditions. Leaves are large and compound. Young leaves show circinate vernation. Vascular tissues and mechanical tissues are present. A cuticle is present covering the areal parts of the pterophytes. On the under surfaces of mature leaflets, near the margin, groups of sporangia or sori are produced. They are covered with a kidney shaped inducium. Sporangia are attached to the placenta or the receptor by long stalks. Sporangia of different stages of development can be seen in a single sorus. Inducium is attached to the apex of the placenta covering all sporangia. In Nephrolepis, there is only one type of spores formed as in Poganatum. Therefore, it is said to be homosporous. Pterophytes are better adapted for terrestrial mode of life when compared to bryophytes.
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What is the difference between Bryophytes and Pterophytes? • In ptrophytes, the dominant phase is the sporophytic generation whereas, in bryophytes, the dominant phase is the gametophytic generation. • In bryophytes, the plant body is not differentiated into roots, true stems or leaves but, in pterophytes, the sporophyte is differentiated into leaves, roots, and stem (rhizome). • In pterophytes, a well-developed root system is present for absorption and anchorage whereas a well developed root system is not present in bryophytes. • In pterophytes, vascular system present with xylem and phloem but, in bryophytes, there is no vascular system. • Areal parts of the pterophyte sporophyte are covered with cuticle for checking transpiration, but there is no cuticle like that in bryophytes. • Stomata are present in pterophytes but absent in bryophytes. • An underground rhizome is present in pterophytes to withstand unfavorable conditions. There is no such structure in bryophytes. • Ramenta and circinate vernation are present in pterophytes and absent, in bryophytes.
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