Non-vascular plants are generally those plants without roots. These include mosses and certain kinds of algae. They grow in water and warm, moist places.
The true non-vascular plants are the algae (notably those with photosynthetic pigments: the green, red and brown and single-cell algae) and bryophytes (mosses, liverworts and hornworts). To this group is often added the fungi, lichens and cyanobacteria, although strictly these are not plants.