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|A thallose liverwort, Lunularia cruciata|
Non-vascular plants is a general term for those plants without a vascular system (xylem and phloem). Although non-vascular plants do not have these tissues, some of them have other tissues for internal transport of water.
The term "non-vascular plant" is no longer used in biological classification. Non-vascular plants include two quite different groups:
- The Bryophyta (mosses), the Marchantiophyta (liverworts), and the Anthocerotophyta (hornworts). Because these plants have no water-conducting tissues, they do not have 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.
In the past, the term non-vascular plant included all the algae, but also the fungi as well. Today, it is recognized that these groups are not closely related to plants, and have a very different biology.