Both lycophytes and horsetails are primitive plants lacking seeds. Both are characterized by two alternating generations (sporophyte and gametophyte) while sporophyte is the dominant generation. In contrast to mosses, lycophytes and horsetails have a vascular system.
Lycophytes inhabit various environments including deserts, wetlands, and rainforests. Some species are completely aquatic. Lycophytes have unique leaves (microphylls) that possess one vein. In some lycophytes, the stem is located below ground while leaves grow from the tip of the stem. Other species of lycophytes have adventitious roots that grow down towards the ground.
Horsetails usually inhabit marshes, unforested areas, wetlands. However, they can be found in different environments. The stem of the plant is characterized by the presence of joints or nodes. Needle-shaped leaves and branches come out as whorls from the joints. Photosynthesis mainly occurs in the green stem. Epidermal cells accumulate silica that provides the stiffness of horsetail plants. Horsetails lack roots and use underground stems (rhizomes) to anchor the plants to the ground. In contrast to lycophytes, some horsetails have dimorphic shoots - one of them is a green photosynthesizing stem while another produces has sporangia and produces spores.
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