What are the three groups of plants that lack specialized conducting tissues and true roots, stems, and leaves?

Bryophytes - the Bryophyta (mosses), the Marchantiophyta (liverworts), and the Anthocerotophyta (hornworts). In these groups, the primary plants are the haploid gametophytes, with the only diploid portion being the attached sporophyte, consisting of a stalk and sporangium. Because these plants lack the water-conducting tissues, they fail to achieve the structural complexity and size of most vascular plants.





Algae - especially the green algae. Recent studies have demonstrated that the algae actually consist of several unrelated groups. It turns out that common features of living in water and photosynthesis were misleading as indicators of close relationship. Only the green algae are still considered relatives of the plants.