Sugars, produced in photosynthesis, must be distributed to the body and roots of the plant that do not photosynthesize. Water and nutrients from the soil, taken up by the roots, must also make their way into the plant body and leaves. To perform these essential functions, plants contain a vascular tissue network, which consists small tubes running throughout the plant. Also characteristic of plants, as well as some algae, are gametangia that protect gametes. These are pockets of cells that protect the egg cell, and where the egg is fertilized.
Plants have a life cycle unlike that of any animal, fungus, or bacteria.
In the alternation of generations, the reproductive cells of the diploid plant, or sporophyte, will undergo meiosis, creating haploid spores. Each spore can undergo mitotic divisions that will eventually form a gametophyte, or a haploid plant. The gametophyte s reproductive cells divide mitotically to produce haploid gametes, which fuse to become a diploid zygote. The zygote grows into a sporophyte, and the process repeats. Typically, the two types of generations have different forms, and one is dominant over the other, which is smaller and grows on the dominant plant.