The ferns are a group of vascular plants that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissues that conduct water and nutrients and in having life cycles in which the branched sporophyte is the dominant phase.
Ophioglossum, the adder's-tongue ferns, is a genus of about 50 species of ferns in the family Ophioglossaceae. The name Ophioglossum comes from the Greek meaning "snake-tongue". Their cosmopolitan distribution is mainly in tropical and subtropical habitats.
The Lycopodiaceae are an old family of vascular plants, including all of the core clubmosses and firmosses, comprising 16 accepted genera and about 400 known species. This family originated about 380 million years ago in the early Devonian, though the diversity within the family has been much more recent. "Wolf foot" is another common name for this family due to the resemblance of either the roots or branch tips to a wolf's paw.
Ophioglossaceae, the adder's-tongue family, is a small family of ferns. In the Pteridophyte Phylogeny Group classification of 2016, it is the only family in the order Ophioglossales, which together with the Psilotales is placed in the subclass Ophioglossidae. The Ophioglossidae are one of the groups traditionally known as eusporangiate ferns. Members of the family differ from other ferns in a number of ways. Many have only a single fleshy leaf at a time. Their gametophytes are subterranean and rely on fungi for energy.
The Aspleniaceae (spleenworts) are a family of ferns, included in the order Polypodiales. The composition and classification of the family have been subject to considerable changes. In particular, there is a narrow circumscription, Aspleniaceae s.s., in which the family contains only two genera, and a very broad one, Aspleniaceae s.l., in which the family includes 10 other families kept separate in the narrow circumscription, with the Aspleniaceae s.s. being reduced to the subfamily Asplenioideae. The family has a worldwide distribution, with many species in both temperate and tropical areas. Elongated unpaired sori are an important characteristic of most members of the family.
Lygodium is a genus of about 40 species of ferns, native to tropical regions across the world, with a few temperate species in eastern Asia and eastern North America. It is the sole genus in the family Lygodiaceae in the Pteridophyte Phylogeny Group classification of 2016. Alternatively, the genus may be placed as the only genus in the subfamily Lygodioideae of a more broadly defined family Schizaeaceae, the family placement used in Plants of the World Online as of November 2019. Per recent molecular evidence, Lygodiaceae is thought to have diverged relatively early from the other members of the Schizaeales due to the relatively high level of synonymous sequence divergence between the families within the Schizaeales.
Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016, Marattiales is the only order in the subclass Marattiidae. The family has six genera and about 110 species. Many are different in appearance from other ferns, having large fronds and fleshy rootstocks.
Lycopodium is a genus of clubmosses, also known as ground pines or creeping cedars, in the family Lycopodiaceae. Two very different circumscriptions of the genus are in use. In the Pteridophyte Phylogeny Group classification of 2016, Lycopodium is one of nine genera in the subfamily Lycopodioideae, and has from nine to 15 species. In other classifications, the genus is equivalent to the whole of the subfamily, since it includes all of the other genera. More than 40 species are accepted.
The Athyriaceae are a family of terrestrial ferns in the order Polypodiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed in the suborder Aspleniineae, and includes two genera. Alternatively, it may be treated as the subfamily Athyrioideae of a very broadly defined family Aspleniaceae. The family has with a cosmopolitan distribution.
Woodwardia is a genus of ferns in the family Blechnaceae, in the suborder Aspleniineae of the order Polypodiales. Species are known as netted-chain ferns. The genus is native to warm temperate and subtropical regions of the Northern Hemisphere. They are large ferns, with fronds growing to 50–300 cm long depending on the species. The fossil record of the genus extends to the Paleocene.
Blechnum, known as hard fern, is a genus of ferns in the family Blechnaceae, subfamily Blechnoideae, according to the Pteridophyte Phylogeny Group classification of 2016. Two very different circumscriptions of the genus are used by different authors. In the PPG I system, based on Gasper et al. (2016), Blechnum is one of 18 genera in the subfamily Blechnoideae, and has about 30 species. Other sources use a very broadly defined Blechnum s.l., including accepting only two other genera in the subfamily. The genus then has about 250 species. In the PPG I circumscription, the genus is mostly neotropical, with a few southern African species.
Trichomanes is a genus of ferns in the family Hymenophyllaceae, termed bristle ferns. The circumscription of the genus is disputed. All ferns in the genus are filmy ferns, with leaf tissue typically 2 cells thick. This thinness generally necessitates a permanently humid habitat, and makes the fronds somewhat translucent. Because of this membrane-like frond tissue, the plant is prone to drying out. “Filmy ferns” in the taxa Hymenophyllaceae grow in constantly wet environments. Many are found in cloud forests such as “Choco” in Colombia. There are also members of the taxa that can grow submersed in water.
Struthiopteris spicant, syn. Blechnum spicant, is a species of fern in the family Blechnaceae, known by the common names hard-fern or deer fern. It is native to Europe, western Asia, northern Africa, and western North America. Like some other species in the family Blechnaceae, it has two types of leaves. The sterile leaves have flat, wavy-margined leaflets 5 to 8 millimeters wide, while the fertile leaves have much narrower leaflets, each with two thick rows of sori on the underside.
Cheiroglossa is a genus of fern in the family Ophioglossaceae, subfamily Ophioglossoideae, with two species. Although recognized as a separate genus in the Pteridophyte Phylogeny Group classification of 2016, other sources regard it as a synonym of the genus Ophioglossum.
The genus Dendrolycopodium is a clubmoss genus in the family Lycopodiaceae. In the Pteridophyte Phylogeny Group classification of 2016, it is placed in the subfamily Lycopodioideae. Some sources do not recognize the genus, sinking it into Lycopodium. It is treated as section Obscura when retained within Lycopodium. The genus includes a discrete group of plants with similar morphologies. All have erect to semi-erect, branched stems.
Anchistea is a genus of leptosporangiate ferns in the family Blechnaceae. It has only one species, Anchistea virginica the Virginia chain fern, which has long creeping, scaly, underground stems or rhizomes giving rise to tall widely separated, deciduous, single leaves. In contrast, the leaves of Osmundastrum cinnamomeum, which can be mistaken for A. virginica, grow in a group from a crown. Also in contrast to O. cinnamomeum the leaves are monomorphic without distinct fertile fronds. The lower petiole or stipe is dark purple to black, shiny and swollen, the upper rachis is dull green. The leaf blade is green and lanceolate, composed of 12 to 23 paired, alternate pinnatifid pinnae. The pinnae are subdivided into 15 to 20 paired segments that are ovate to oblong. The lower rachis is naked for about half its length. The sori or spore-producing bodies are found on the underside of the pinnae and are long and form a double row which outlines the major veins of the pinnae. In common with all ferns, A. virginica exhibits a gametophyte stage in its life cycle and develops a haploid reproductive prothallus as an independent plant. The spores are produced in red-brown sori which line the spaces (areolae) between the costa and costules. Further photographs can be found at the Connecticut Botanical Society and Ontario Ferns websites.
Ctenopterella is a genus of ferns in the family Polypodiaceae, subfamily Grammitidoideae, according to the Pteridophyte Phylogeny Group classification of 2016 (PPG I). It is known from Africa through southeast Asia and Oceania to Polynesia.
Pseudolycopodium is a genus of lycophyte in the family Lycopodiaceae with only one species, Pseudolycopodium densum, known as the bushy clubmoss. In the Pteridophyte Phylogeny Group classification of 2016, the genus is placed in the subfamily Lycopodioideae. Some sources do not recognize the genus, sinking it into Lycopodium. Pseudolycopodium densum is native to Australia, the North Island of New Zealand and New Caledonia. It is a spore-bearing vascular plant and grows up to a metre high. It is found in a wide variety of situations, often in high rainfall areas on sandy soils.
Hemionitis is a genus of ferns in the subfamily Cheilanthoideae of the family Pteridaceae. Its circumscription varies greatly in different systems of fern classification. In the Pteridophyte Phylogeny Group classification of 2016, it was one of more than 20 genera in the subfamily Cheilanthoideae, and was said to have five species. Other sources treat it as the only genus in the subfamily, and so accept about 450 species. With the restricted circumscription, species are native to tropical America.
Elaphoglossum is a genus of ferns in the family Dryopteridaceae, subfamily Elaphoglossoideae, in the Pteridophyte Phylogeny Group classification of 2016.
