Adiantaceae
Encyclopedia
Adiantaceae is a family of fern
s in the order Pteridales
. This includes the family formerly known as the "Vittariaceae." Recent genetic analyses based on chloroplast
gene
s demonstrate that the vittarioid ferns cladistically nest within the genus Adiantum, making that genus paraphyletic.
The vittarioid ferns are primarily epiphytic
in tropical regions and all have simple leaves with sori
that follow the veins and lack true indusia; the sori are most often marginal with a false indusium formed from the reflexed leaf margin. The family also includes a species, Vittaria appalachiana, that is highly unusual in that the sporophyte
stage of the life cycle is absent. This species consists solely of photosynthetic
gametophyte
s that reproduce asexually.
The ferns historically considered as Adiantum include both petrophilic and terrestrial plants. Most of the species in this genus do compose a clade within the family, but apparently Adiantum raddianum and possibly some related species constitute a clade that is sister to the vittarioids combined with the rest of the genus Adiantum.
This family is most closely allied with the Pellaeaceae within the Pteridales
.
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
s in the order Pteridales
Pteridales
The Pteridales are ferns that have their sori in linear strips under the edge of the leaf tissue, usually with the edge of the lamina reflexed over.This order is considered a family under the Smith classification...
. This includes the family formerly known as the "Vittariaceae." Recent genetic analyses based on chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s demonstrate that the vittarioid ferns cladistically nest within the genus Adiantum, making that genus paraphyletic.
The vittarioid ferns are primarily epiphytic
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
in tropical regions and all have simple leaves with sori
Sorus
A sorus is a cluster of sporangia .In fungi and lichens, the sorus is surrounded by an external layer. In some red algae it may take the form of a depression into the thallus....
that follow the veins and lack true indusia; the sori are most often marginal with a false indusium formed from the reflexed leaf margin. The family also includes a species, Vittaria appalachiana, that is highly unusual in that the sporophyte
Sporophyte
All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or algae that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants...
stage of the life cycle is absent. This species consists solely of photosynthetic
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
gametophyte
Gametophyte
A gametophyte is the haploid, multicellular phase of plants and algae that undergo alternation of generations, with each of its cells containing only a single set of chromosomes....
s that reproduce asexually.
The ferns historically considered as Adiantum include both petrophilic and terrestrial plants. Most of the species in this genus do compose a clade within the family, but apparently Adiantum raddianum and possibly some related species constitute a clade that is sister to the vittarioids combined with the rest of the genus Adiantum.
This family is most closely allied with the Pellaeaceae within the Pteridales
Pteridales
The Pteridales are ferns that have their sori in linear strips under the edge of the leaf tissue, usually with the edge of the lamina reflexed over.This order is considered a family under the Smith classification...
.
Sources
- Schuettpelz, Eric, Harald Schneider, Layne Huiet, Michael D. Windham, Kathleen M. Pryer. "A molecular phylogeny of the fern family Pteridaceae: Assessing overall relationships and the affinities of previously unsampled genera." Molecular Phylogenetics and Evolution, 44: 1172–1185. 2007: http://www.pryerlab.net/publication/fichier1047.pdf
- Lindsay, Stuart (2003) Considerations for a revision of the fern family Vittariaceae for Flora Malesiana. Telopea 10(1) : 99-112.