A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the large leaves of cycads, as well as palms (Arecaceae) and various other flowering plants, such as mimosa or sumac. "Frond" is commonly used to identify a large, compound leaf, but if the term is used botanically to refer to the leaves of ferns and algae it may be applied to smaller and undivided leaves.
Asplenium platyneuron, commonly known as ebony spleenwort or brownstem spleenwort, is a fern native to North America east of the Rocky Mountains. It takes its common name from its dark, reddish-brown, glossy stipe and rachis, which support a once-divided, pinnate leaf. The fertile fronds, which die off in the winter, are darker green and stand upright, while the sterile fronds are evergreen and lie flat on the ground. An auricle at the base of each pinna points towards the tip of the frond. The dimorphic fronds and alternate, rather than opposite, pinnae distinguish it from the similar black-stemmed spleenwort.
Water fern is a common name for several plants and may refer to:
Gymnosphaera atropurpurea, synonyms Alsophila atropurpurea and Cyathea atropurpurea, is a species of tree fern native to the islands of Luzon, Mindanao, Leyte and Mindanao in the Philippines, where it grows in forest at above 1000 m. The erect trunk is slender and may be up to 3 m tall. Fronds are bipinnate and 1–2 m long. Characteristically of this species, the final pair of pinnae are usually reduced and occur towards the base of the stipe. These, along with the stipe bases, are persistent and retained around the trunk long after withering. The stipe itself is dark and covered with scales, which are either small, dull and brown or large, dark and glossy. Sori occur near the midvein of fertile pinnules and lack indusia. Fertile pinnules are notably smaller than sterile ones.
Gymnosphaera commutata is a Malesian species of tree fern found in wet and swampy forests.
Polystichum acrostichoides, commonly denominated Christmas fern, is a perennial, evergreen fern native to eastern North America, from Nova Scotia west to Minnesota and south to Florida and eastern Texas. It is one of the most common ferns in eastern North America, being found in moist and shady habitats in woodlands, stream banks and rocky slopes. The common name derives from the evergreen fronds, which are often still green at Christmas.
Frond dimorphism refers to a difference in ferns between the fertile and sterile fronds. Since ferns, unlike flowering plants, bear spores on the leaf blade itself, this may affect the form of the frond itself. In some species of ferns, there is virtually no difference between the fertile and sterile fronds, such as in the genus Dryopteris, other than the mere presence of the sori, or fruit-dots, on the back of the fronds. Some other species, such as Polystichum acrostichoides, or some ferns of the genus Osmunda, feature dimorphism on a portion of the frond only. Others, such as some species of Blechnum and Woodwardia, have fertile fronds that are markedly taller than the sterile. Still others, such as Osmunda cinnamomea, or plants of the family Onocleaceae, have fertile fronds that are completely different from the sterile.
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.
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.
Cranfillia fluviatilis, synonym Blechnum fluviatile, is a fern known in the Māori language as kiwikiwi. A herbaceous plant, C. fluviatilis is a "hard fern" of the genus Cranfillia in the family Blechnaceae. It was identified by Patrick Brownsey in 1979. Other common names are star fern, creek fern, kawakawa and kiwakiwa.
Parablechnum cordatum, the Chilean hard fern or costilla de vaca, is a fern of the family Blechnaceae, native to Chile. It is also found in neighboring areas of Argentina and the Juan Fernández Islands.
Lomaria discolor, synonym Blechnum discolor, commonly called crown fern, is a species of fern in the family Blechnaceae. This species is endemic to New Zealand. As noted by C. Michael Hogan, this species is found in a number of forest communities in diverse locations within New Zealand, and is sometimes a dominant understory component.
Austroblechnum durum, synonym Blechnum durum, is a species of fern in the family Blechnaceae. The fern is endemic to New Zealand.
Austroblechnum lanceolatum, synonym Blechnum chambersii, is a species of fern within the family Blechnaceae, found in Australia, New Zealand, Samoa and Fiji.
Parablechnum wattsii, synonym Blechnum wattsii, is a common terrestrial fern growing in rainforest and open forest. It is often seen near creeks in much of south eastern Australia, including Victoria, Tasmania, South Australia, New South Wales and Queensland. The specific epithet wattsii honours William Walter Watts (1856-1920). Watts was considered an authority on mosses and ferns and has more than 30 species named for him. Common names by which the species may be called are hard water fern - from its stiff leathery fronds, leech fern - as forest workers often encounter leaches while working in clusters of these ferns, hard hill fern - from the fern's habit and habitat, and red cabbage fern - from the bronze-pink colour of the young fronds resembling cooked red cabbage.
Lomaria nuda, commonly known as the fishbone waterfern, is a fern that grows up to a metre tall, and is abundant in rainforest and eucalyptus forests in eastern Australia. The species is placed in the genus Lomaria in the Pteridophyte Phylogeny Group classification of 2016, but is often retained in genus Blechnum as Blechnum nudum.
Pellaea nana, known as dwarf sickle fern, is a fern species in the subfamily Cheilanthoideae of the family Pteridaceae. It grows in eastern Australia, in rainforest or moist eucalyptus forest, often on rocks, cliffs and large boulders. Also found growing on Lord Howe Island. The original specimen was collected by Allan Cunningham at the Brisbane River. In the state of Victoria, this plant is considered rare. The specific epithet nana is derived from the Latin word nanus meaning dwarf.
Austroblechnum patersonii, synonym Blechnum patersonii, is a fern in the family Blechnaceae. It is known as the strap water-fern.
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.
Icarus is a genus of ferns in the family Blechnaceae, subfamily Blechnoideae, with a single species Icarus filiformis, according to the Pteridophyte Phylogeny Group classification of 2016. The genus is accepted in a 2016 classification of the family Blechnaceae, but other sources sink it into a very broadly defined Blechnum, equivalent to the whole of the PPG I subfamily.
