They have a multicellular diploid embryo stage that remains developmentally and nutritionally dependent on the parental gametophyte for a significant period (and hence the name embryophyte is given to plants) and tissue -generating parenchymatous meristems at the shoot and root apices, producing tissues that differentiate in wide variety of shapes. dMoreover, all plants have a digenetic life cycle with an alternation between a haploid gametophyte and a diploid sporophyte. Algae do not have any of these features; they do not have roots, stems, leaves, nor well-defined vascular tissues.