Higher plants are those types of plants that have come to land and adapted to their new habitat. There are more than 300 thousand species. Higher plants are distinguished by the presence of vegetative organs, such as root and shoot, and have the same photosynthetic pigments: chlorophyll and carotenoids.
Higher plants, for the most part, have a complex transport system of substances that can regulate the evaporation of water through leaves. Cells of higher plants form tissues. Sporophyte prevails in the life cycle (except bryophytes).
Gametophyte is gradually reduced to several cells. The organs of sexual and asexual reproduction are multicellular. Fertilization with the complication of species is no longer dependent on water. The zygote gives rise to a multicellular embryo.
Higher land plants make up the bulk of the Earth’s biomass - about 90%.
Systematics of higher plants
Higher plants include higher spore and higher seed plants.
Higher spores : rhinoiformes (exclusively fossils), psilotiformes (about 20 species have survived), bryophytes (23-27 thousand species), plauiform (about 1300 species), pine-like (about 30 species), fern-shaped (about 12,000 species).
Higher plants that reproduce by spores, botanists share a common name - higher spore. These include both existing and extinct species. The body of the higher spore is divided into aboveground and underground parts, vegetative organs are developed. The life cycle consists of alternating generations: sporophyte and gametophyte. Sporophyte is well developed, lives for a long time (bryophytes are the exception). It develops multicellular sporangia, from which immobile haploid spores form after meiosis. They are unicellular, small in size, distributed mainly by the wind and germinate in the gametophyte.
Fertilization of higher spores occurs only in the presence of water. By the location of the reproductive organs , bisexual plants (which have male and female cells) and same-sex plants (there are either male or female cells) are distinguished.
Disputes may be different and the same in size. Higher spore plants that have the same spores are called equal spores, and those with different spores are called sporeless. Depending on the size, microspores (small in size) and megaspores (large) are distinguished.
It is believed that seed plants originated directly from spore plants, in particular from ferns.
Higher seed plants: pinophytes (gymnosperms) - about 800 species, magnoliophytes (angiosperms) - 300 thousand species.
Higher seed plants reached their heyday in the Mesozoic era, when the climate became more arid and colder, a change of seasons appeared. Currently, angiosperms are the most common.
Seed plants have several advantages over higher spore ones. They consist of the same organs: root, shoot, seed. The trunk is much stronger than that of the spore, as wood cells grow on it. In this case, the bulk of the wood cells is dead.
Seed plants are extremely heterogeneous. Gametophyte develops on sporophyte and feeds on it.
Propagation occurs through seeds, which are multicellular formed embryos that include a supply of nutrients. Fertilization of the highest seeds is preceded by pollination - the transfer of pollen grains to the seed buds with an egg. Pollination is carried out using wind, water, animals, insects. Fertilization ceases to depend only on water, as in higher spores. It occurs due to a vegetative pollen cell that grows into a pollen tube.