However, even Tree Ferns are relatively small plants compared to woody Angiosperms and Gymnosperms. We will concentrate on the Filicales which contains most extant species. They are most abundant in the tropics but some species can be found in the arctic alpine zone. Ferns typically have subterranean stems called Rhizomes . Some species have Stolons.
Most species are terrestrial but some are epiphytic and a few are aquatic.
Some species produce significant aerial stems and resemble small trees. Roots are adventitous and arise from the stem . The stems of tree ferns have a thick coat formed by adventitous roots which are initiated near the apex of the stem and grow down the outside of the stem . This has some obvious disadvantages . The roots must travel a long distance through the atmosphere before reaching the soil.