- Related Topics:
- Pteridoid
- Cheilanthoid
- Ceratopteridoid
- Adiantoid
- Crytogrammoid
Pteridaceae
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What is the Pteridaceae plant family?
The Pteridaceae family, also known as maidenhair ferns, falls under the order Polypodiales and includes roughly 950 species across 50 genera. These ferns are found worldwide, particularly in tropical and warm-temperate climates, and display significant ecological diversity, from aquatic environments to arid, rocky habitats.
Pteridaceae is characterized by spore-producing structures (sporangia) along the veins or at vein tips. Key features include leptosporangiate sporangia arising from single cells, unprotected sporangia in grooves, or false indusia formed by rolled leaf margins. Their leaves are usually compound, growing from creeping or upright rhizomes.
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What types of plants belong to the Pteridaceae family?
The Pteridaceae, also known as the maidenhair fern family, contains roughly 50 genera and 950 species. They can be found worldwide, especially in tropical and warm-temperate climates. Pteridaceae are ecologically diverse, ranging from floating aquatic plants to rock ferns.
One of five clades within Pteridaceae is the Pteridoid clade. Pteris (brakes) is the largest genus in this group, with about 300 species found in tropical and warm temperate regions. Pityrogramma, or the gold- and silver-backed ferns, consists of about 16 tropical species. Other genera include Anopteris, Ochropteris, and Neurocallis, each having a single species with restricted distributions in the tropics, and Jamesonia (formerly Eriosorus) which occurs at high elevations.
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Where are Pteridaceae plants commonly found in nature?
Members of the Pteridaceae, or maidenhair fern, family can be found worldwide, especially in tropical and warm-temperate climates. This plant family is ecologically diverse, with species ranging from floating aquatic plants to rock ferns in deserts and seasonally dry areas.
The Pteridoid clade within Pteridaceae includes the genus Pteris (brakes), which has roughly 300 species found in tropical and warm temperate regions. Pityrogramma, or the gold- and silver-backed ferns, consists of about 16 tropical species.
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What are some physical features that help identify Pteridaceae plants?
The Pteridaceae, or maidenhair fern family, has around 50 genera and 950 species that are found worldwide, especially in tropical and warm-temperate regions.
Key physical features of Pteridaceae plants:
- Sporangia These spore-producing structures are located in lines along the veins or at the vein tips.
- Leptosporangiate ferns Their sporangia characteristically arise from a single cell.
- False indusium The spore structures may be unprotected in grooves or covered by the rolled leaf margin. True indusia are seldom produced.
- Spores Commonly globose (tetrahedral).
- Leaves Usually compound.
- Rhizomes Creeping or upright.
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How do Pteridaceae ferns reproduce?
Ferns in the family Pteridaceae reproduce through a process called alternation of generations, between gametophytes and sporophytes. The typical fern, or sporophyte, has stems, leaves, and roots, and its cells have two sets of chromosomes. Most ferns are perennial, living for several years, and reproduce vegetatively through branching rhizomes, which can form large, genetically uniform colonies or clones. Some ferns also propagate through root or leaf proliferations.
Spores, which have only one set of chromosomes, are produced in sporangia on the leaves. Carried by wind, a small percentage of spores land in suitable spots and form gametophytes, also known as prothallia. Prothallia are small, typically less than 8 mm long, and kidney-shaped. Sperm and eggs produced on the gametophytes facilitate fertilization. The resulting embryo is held within the prothallium until it grows into an independent plant.
Many ferns in the Pteridaceae family have developed a modified life cycle called apogamy, in which fertilization is bypassed.
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Why are Pteridaceae plants important in ecosystems or to humans?
Members of the Pteridaceae family have both ecological and economic importance. Ecologically, they can be found in diverse environments, from aquatic habitats to deserts. The mosquito fern (Azolla) houses blue-green algae that convert nitrogen to usable forms, increasing the productivity of rice paddies. Economically, many species are used in horticulture for decoration, while some have served as minor food sources and medicine. However, Pteridium aquilinum is a noxious weed in many countries because it is poisonous and reduces the grazing value of land. Also, certain ferns like Osmunda and Pteridium, which are commonly consumed in East Asia, have been shown to be strongly carcinogenic.
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Pteridaceae, the maidenhair fern family (order Polypodiales), containing about 50 genera and approximately 950 species. Members of Pteridaceae are distributed throughout the world, especially in tropical and warm-temperate regions. The plants are extremely diverse ecologically, ranging from floating aquatic plants to rock ferns in deserts and seasonally arid places. Some species are cultivated as ornamentals.
The family is characterized by spore-producing structures (sporangia) located in lines along the veins or at the vein tips. As leptosporangiate ferns, members of Pteridaceae have sporangia that characteristically arise from a single cell. These structures may be unprotected (lacking indusium) in grooves or covered by the rolled leaf margin (false indusium). True indusia are seldom produced. The spores are commonly globose (tetrahedral). The leaves (fronds) are usually compound, and the plants bear creeping or upright rhizomes.
The members of Pteridaceae have been variously subdivided by botanists and include five (or more) relatively well-marked groups (clades) of genera whose classification remains controversial. The five clades given here have been treated as one or more separate subfamilies by some pteridologists (botanists who study ferns).
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Adiantoid clade
The Adiantoid clade contains 6β12 genera and some 300 species. Members of Adiantum (about 250 species), often called maidenhair ferns, are characterized by sporangia positioned on the underside of small flaps of tissue along the leaflet margins. Northern maidenhair (A. pedatum) is found in the woods of eastern North America, with close relatives in western North America and East Asia.
Most botanists consider the former family Vittariaceae to be closely related to the maidenhair ferns and have reassigned it to the Adiantoid clade of Pteridaceae, though the plants are somewhat dissimilar in appearance from members of Adiantum. This group contains some 140 species classified into 5β11 genera, the largest being Vittaria (shoestring ferns) and Antrophyum, both found throughout the tropics. Most of these species have undivided strap-shaped leaves, with the sporangia either in long lines along the veins or more commonly in elongate grooves.
Pteridoid clade
The Pteridoid clade contains 14β17 genera and about 400 species. The largest genus, Pteris (brakes), consists of about 300 species distributed throughout tropical and warm temperate parts of the world and is known for the large number of hybrids between various species. Pityrogramma, or the gold- and silver-backed ferns, consists of about 16 tropical species, which are occasionally cultivated in greenhouses for the colourful yellow or white farina found on the lower leaf surfaces of most species. The species of the former genus Eriosorus are now placed in Jamesonia. They occur at high elevations, such as the Andean paramos, and some of the species have leaves that drape over other vegetation and continue to uncurl from an indeterminate apex. Anopteris, Ochropteris, and Neurocallis each have a single species and highly restricted distributions in the tropics; their taxonomy is contentious.
Cheilanthoid clade
The Cheilanthoid clade includes 20 genera and about 400 species. The major genera include Pellaea (cliff brakes) and Cheilanthes (lip ferns), both of which tend to grow on rock cliffs or ledges. Many of the species in this clade occur in arid or seasonally dry environments and exhibit a great variety of morphological adaptations to drought stress, including leaves with thick waxy outer layers, dense hairs or scales, powdery covering of farina, and the ability to curl up their leaves during drought, uncurling them later when rain returns.
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Crytogrammoid clade
The Crytogrammoid clade contains three genera and about 23 species. The three small genera, Cryptogramma (parsley ferns), Coniogramme, and Llavea, are unusual morphologically, and their position relative to the closely related Pteridoid clade requires further study.
Ceratopteridoid clade
The Ceratopteridoid clade contains two genera and six species. Acrostichum consists of three species of large leathery-leaved ferns adapted to brackish and saline swamps in tropical coastal areas worldwide. Ceratopteris also contains three species, which occur in tropical and warm temperate regions and are floating aquatics. They have been used as aquarium and pond plants and are popular teaching tools in genetics.