Onoclea sensibilis | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Division: | Polypodiophyta |
Class: | Polypodiopsida |
Order: | Polypodiales |
Suborder: | Aspleniineae |
Family: | Onocleaceae |
Genus: | Onoclea |
Species: | O. sensibilis |
Binomial name | |
Onoclea sensibilis | |
Onoclea sensibilis, the sensitive fern, also known as the bead fern, is a coarse-textured, medium to large-sized deciduous perennial fern. The name comes from its sensitivity to frost, the fronds dying quickly when first touched by it. It is sometimes treated as the only species in Onoclea, [2] but some authors do not consider the genus monotypic. [3]
The sterile and fertile fronds of Onoclea sensibilis have independent stalks originating from the same rhizome, quite different from other ferns. [4] The bright, yellow-green trophophylls (sterile fronds) are deeply pinnatifid and are typically borne at intervals along the creeping rhizome. The sterile fronds are deciduous with trophopods, swollen bases, that serve as over winter storage organs. [5] [6] The sterile fronds of O. var. sensibilis have a length of 1–1.3 m (3–4 ft) with 5–11 pinnae, leaf pairs, evenly spaced along the stipe. [7] O. var. interrupta Maxim. fronds are shorter, 20–50 cm (8–20 in) long, with fewer pinnae, only 5–8 pairs. [8]
The sporophylls (fertile fronds) are smaller, 20–45 cm (8–18 in) in length, [8] non-green at maturity and have very narrow pinnae. They are persistent, standing 2–3 years. The sori comprise clusters of sporangia (spore cases) 2–4 mm (1/10–1/6 in) in diameter, [7] like beads, on upright fertile fronds, hence the common name Bead fern.
Sori are typically bilaterally symmetrical, though leaf forms have been observed with pinnae fertile only on a single side of the rachis. This form, named O. sensibilis L. F. hemiphyllodes (Kiss & Kümmerle, 1926) [9] and a second, O. sensibilis L. F. obtusilobata having flat pinnules (not curled or bead shaped), [9] were deemed to be variations not meriting taxonomic recognition (J. M. Beitel et al. 1981). [10]
The fiddleheads have a pale reddish color.
The spermatogenesis process spans formation of spermatogenous cells to the release of spore. In homosporous ferns, like O. sensibilis L., developing spermatids are surrounded by two different walls at specific development stages, as opposed to a single wall reported in other species. Other differences include a delayed formation of the osmiophilic crest and during sperm release the cap cell removes intact, as opposed to forming a pore or collapsing altogether. [11] Spores are monolete with the antheridium, or sporangium, containing either 32 or 64 sperm spores, [11] usually being 64. [5] Regardless of the number, the capsule's volume remains nearly the same. [11]
The mechanics of spore release and its timing are controlled by springtime humidity. [12] The small fertile margins, that in live-form held spore in tightly rolled structures, maintain their dry, leathery shape over winter. These pinnules respond to spring's higher humidity by opening, releasing their spore into the air. Subsequent gametophytes are unisexual in early development, favoring cross-fertilization, later becoming bisexual to ensure species survival. [13]
The genus Onoclea was cast by Carl Linnaeus in 1751, separating from the fern's prior association with the Angiopteris genus. [14] The binominal name, Onoclea sensibilis, was published in his 1753 Species Plantarum . [15]
Onoclea sensibilis has two geographically disjunctive varieties. Onoclea sensibilis var. sensibilis is native to North America; Canada's central and eastern regions and the United States' north, central and eastern regions. [6] Onoclea sensibilis var. interrupta Maximowicz (aka Maxim.) is native to Southeast Siberia, Japan and China. [8] The varietal difference is their ultimate height, O. var. interrupta Maxim. only reaching half the height of its sister.
Regional colloquial names for Onoclea sensibilis, the sensitive fern, focus on its characteristics.
Onoclea sensibilis' name was descriptive. Onoclea comes from the Greek onos, meaning a vessel, and kleio, meaning to close, describing the closely rolled sori on its fertile fronds. Its species, from the Late Latin sensibilis, means sensitive, describing its high sensitivity to autumn's first frost and to drought. [23] [17]
Onoclea sensibilis is native to Northern Hemisphere temperate regions; the Russian Far East, China and Eastern Asia, and a wide native distribution in Northern America. [22] It ranges from Newfoundland south to Florida and west to Texas, the Rocky Mountains, North and South Dakota, Quebec, and Manitoba. [24] [25] [26]
It has become naturalized in western Europe [27] and New Zealand. [5]
Onoclea sensibilis can be found at elevations from sea level up to 1,500 metres (4,900 ft) [7] in fresh water habitats, [10] not brackish, as its spore germination ceases at salt (NaCl) levels ≥ 0.6%, [28] moderately saline water and higher.
Onoclea sensibilis grows best in moist shaded or partially shaded areas, dwelling in a variety of swamp and wood habitats: wet meadows, thickets and bogs, as well as stream and riverbanks and roadside ditches. It tolerates extremely wet soils, appearing in soggy ground or at the very edge of water in shade or sun. [16] The plant can tolerate dryer conditions in shade.
It prefers acidic (pH <6.8), loose, sandy to loam, limestone-based soils.
The Onoclea sensibilis plant has remained essentially unchanged over millions of years. A fifty-seven million year old fossil of Paleocene epoch flora shows specimens virtually identical to modern samples. [6] It has a life cycle featuring alternation of generations, sexual and asexual reproduction; its sporophyte generation matures in autumn, casts its spores in the spring [7] and the gametophyte generation follows. Sporophytes require 5–10 years of growth before reaching their mature fern height. [29]
Sensitive ferns propagate by both spore dispersion and rhizome growth. Its growth clusters attract local fauna where small wildlife find habitat, [17] deer bed upon its dense mat [19] and in winter wild turkeys use the fertile spore stalks as a secondary food source. [17] They can become aggressive [23] and a nuisance if established near preferable vegetation. The University of Maine's Cooperative Extension: Maine Wild Blueberries classifies the sensitive fern as a herbaceous broadleaf weed. [30]
Its deciduous fronds do not tolerate freezing temperatures, however, the plant survives USDA hardiness zones 4–8, [31] or minimum temperatures of −20 °C to −15 °C (−4 °F to 5 °F) having the Royal Horticultural Society's H6 rating. [32] Winter survival is enhanced if the dried frond petiole bases are left intact. [5] [2]
Nutrient beneficial ectotrophic mycorrhizal associations may occur in Onoclea sensibilis, Pteridium aquilinum and Adiantum pedatum located in oak and hickory forests. [33]
Onoclea sensibilis is a wetland indicator, listed as a Facultative Wetland Hydrophyte in the 2013 (US) National Wetland Plant List due to its observed affinity for wetter soils. [34]
Opinion is mixed regarding the species' tolerance to disturbance of its growing environment. In one forest setting, a decade long decline was noticed following even single-cut tree felling operations. [17] In other settings sensitive ferns appear opportunistic, disturbance not being a problem. [26] They spread to form colonies, often the first species to inhabit disturbed areas.
Onoclea sensibilis hosts insects, fungi, bacteria and even a parasitic vine, Cuscuta gronovii (scaldweed), that can overgrow and constrict it. [35]
Insects feeding upon the Onoclea sensibilis target both its leaves and rhizome roots. Amphorophora ampullata fern aphids, [4] Chirosia gleniensis fern miners [36] and the larvae of sawflies Hemitaxonus dubitatus [4] and Stromboceros delicatulus [37] feed on its leaves. Larvae of moth species Phlogophora iris (olive angle shades, pictured), [10] Callopistria cordata (silver-spotted fern moth) [10] and Papaipema inquaesita (Sensitive Fern Borer) [36] [10] are known to feed on both stems and rhizomes. [4]
Parasitic fungi include Ceratobasidium anceps , causing frond and stem necrosis; Ceratobasidium cornigerum , covering stems with saprophyte growths; [35] and Uredinopsis mirabilis, [35] a distinct rust species unique to the Sensitive Fern. [38] Invasive fungi like Taphrina filicina , [35] Taphrina hiratsukae [39] and Phyllactinia corylea , synonym Phyllactinia guttata [39] can infect leaves, causing blisters or white powdery mildew.
Fungi can develop beneath beech trees, where aphid honeydew secretions accumulate; [40] [41] these strictly epiphyllous honeydew fungi, Sclerotiomyces colchicus [42] and Scorias spongiosa (Schwein.) Fr., [43] have been recorded on Onoclea sensibilis, where their sooty mold buildup impairs leaf function.
Onoclea sensibilis can host Burkholderia plantarii [22] which causes stem lesions. B. plantarii is a pathogen of bacterial seedling blight in rice. In a multi-year study the weedy presence of O. sensibilis at rice paddy fields and a means to convey the bacterium (rainfall runoff) implicated it as the source of bacterial blight outbreaks when paired with enabling environmental conditions. [44]
Onoclea sensibilis has two internally-synthesized chemical defenses against insects. Ingesting any part of the plant introduces thiaminase enzymes and phytoecdysteroid hormones which can disrupt an insect's molting cycle, preventing its full development. [6]
Onoclea sensibilis has been implicated in equine poisoning and death, [45] especially if eaten in quantity. [4] The exact cause is unproven, but thiaminase poisoning, causing an extreme Vitamin B1 deficiency is suspected. [6]
Its human toxicity is not well defined; no specific warnings for Onoclea sensibilis have been found. [31] Its summaries, however, frequently include precautionary statements that ferns, in general, may contain natural carcinogens and/or the enzyme thiaminase, the latter being dangerous in high concentration. [31] [17] Historically, some Native American peoples have consumed Onoclea sensibilis without apparent distress; see Food uses in this article.
Onoclea sensibilis has limited value for food use, [17] considered a famine food by some and reserved for times of scarcity. Cooking heat eliminates its thiaminase content. [31] The Iroquois treated Onoclea sensibilis as an early springtime vegetable, prepared like spinach, the fiddleheads cooked and "seasoned with salt, pepper or butter" (Waugh, 1916). [19] After removing the "brown scales" (sori), leaves were processed likewise. [31] Its young shoots have been sold as delicacies in Asian markets. [31]
It is cultivated as an ornamental plant in traditional and native plant gardens, and in natural landscaping and habitat restoration projects. [23] [29] It has gained the Royal Horticultural Society's Award of Garden Merit. [32] Gardeners employ rhizome division [31] and are aided by spore harvesting guides. [46] Its decomposing fronds make an effective mulch, suppressing undergrowth. [31] Plantings can become aggressive, [29] weedy if not sited properly.
Its cut fronds are used in dried flower arrangements. [16] [31]
Historically, Native American peoples used Onoclea sensibilis for oral and topical indigenous treatments. [47]
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.
Platycerium is a genus of about 18 fern species in the polypod family, Polypodiaceae. Ferns in this genus are widely known as staghorn or elkhorn ferns due to their uniquely shaped fronds. This genus is epiphytic and is native to tropical and temperate areas of South America, Africa, Southeast Asia, Australia, and New Guinea.
Pleopeltis polypodioides, also known as the resurrection fern, is a species of creeping, coarse-textured fern native to the Americas and Africa.
Polystichum munitum, the western swordfern, is an evergreen perennial fern native to western North America, where it is one of the most abundant ferns in forested areas. It occurs along the Pacific coast from southeastern Alaska to southern California, and also inland east to southeastern British Columbia, northern Idaho and western Montana, with disjunctive populations in northern British Columbia, Canada; the Black Hills in South Dakota, United States; and Guadalupe Island off of Baja California, Mexico. Western swordfern is known to have locally naturalized in parts of Great Britain and Ireland.
Onoclea is a genus of plants in the family Onocleaceae, native to moist habitats in eastern Asia and eastern North America. They are deciduous ferns with sterile fronds arising from creeping rhizomes in spring, dying down at first frost. Fertile fronds appear in late summer. Depending on the authority, the genus contains one to five species.
Osmunda regalis, or royal fern, is a species of deciduous fern, native to Europe, Africa and Asia, growing in woodland bogs and on the banks of streams. The species is sometimes known as flowering fern due to the appearance of its fertile fronds.
Athyrium niponicum, the Japanese painted fern, is a species of fern native to eastern Asia.
Onocleaceae is a small family of terrestrial ferns in the order Polypodiales. It is placed in the suborder Aspleniineae in the Pteridophyte Phylogeny Group classification of 2016. Alternatively, the family, along with Blechnaceae, may be placed in a very broadly defined family Aspleniaceae as the subfamily Blechnoideae. The family may contain from one to four genera, consisting of five species largely in north temperate climes. The four genera, Matteuccia, Onoclea, Onocleopsis and Pentarhizidium, may be included under the single genus Onoclea.
Myriopteris clevelandii, formerly known as Cheilanthes clevelandii, is a species of lip fern known by the common name Cleveland's lip fern. It is native to southern California and Baja California in Mexico. The leaf is divided into small, bead-like segments densely covered with scales beneath. In M. clevelandii, some of these scales are reduced to hairlike structures, which help distinguish it from the closely related M. covillei. It is usually found growing on exposed rock, particularly igneous rock.
Polypodium glycyrrhiza, commonly known as licorice fern, many-footed fern, and sweet root, is a summer deciduous fern native to western North America, where it is found in shaded, damp locations.
Amauropelta noveboracensis, the New York fern, is a perennial species of fern found throughout the eastern United States and Canada, from Louisiana to Newfoundland, but most concentrated within Appalachia and the Atlantic Northeast. New York ferns often forms spreading colonies within the forests they inhabit.
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.
Adiantum viridimontanum, commonly known as Green Mountain maidenhair fern, is a fern found only in outcrops of serpentine rock in New England and Eastern Canada. The leaf blade is cut into finger-like segments, themselves once-divided, which are borne on the outer side of a curved, dark, glossy rachis. These finger-like segments are not individual leaves, but parts of a single compound leaf. The "fingers" may be drooping or erect, depending on whether the individual fern grows in shade or sunlight. Spores are borne under false indusia at the edge of the subdivisions of the leaf, a characteristic unique to the genus Adiantum.
Dryopteris macropholis is a species of fern. It is distributed on the Marquesas Islands.
Asplenium tutwilerae is a rare epipetric fern found only in Hale County, Alabama, United States. A. tutwilerae is a fertile allotetraploid, formed by the chromosomal doubling of a specimen of the sterile diploid A. × ebenoides, a hybrid of A. platyneuron and A. rhizophyllum. Except for its spores, which are fertile rather than malformed, A. tutwilerae is essentially identical to A. × ebenoides and was described as part of that species until 2007. It is named in honor of Julia Tutwiler, who discovered the only known wild population at Havana Glen in 1873.
Myriopteris tomentosa, formerly known as Cheilanthes tomentosa, is a perennial fern known as woolly lipfern. Woolly lipfern is native to the southern United States, from Virginia to Arizona and Georgia, and Mexico.
Lygodium articulatum, commonly referred to as mangemange or Bushman's mattress, is a fern endemic to the North Island forests of New Zealand. Mangemange is an endemic species and is unique compared to other ferns in the area due to the vine–like curtain it creates in the canopy. Although the majority of the plant is found in the canopy of the surrounding forest, the roots and stem of mangemange form on the ground, meaning it cannot be classified as an epiphyte.
Myriopteris yatskievychiana is a small fern native to Mexico, a member of the family Pteridaceae. It is known only from a single collection in the Mexican state of Sonora. While superficially similar to golden lip fern, a widespread species in Mexico, differences in its coating of hairs and its small size make it distinctive. One of the cheilanthoid ferns, it was usually classified in the genus Cheilanthes until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes.
Hymenophyllum rarum, the narrow filmy-fern, is a species of fern from the family Hymenophyllaceae. This thin-leaved fern is commonly found in New Zealand and Tasmania, growing in patches on rocks and is epiphytic on trees and tree ferns, growing in moist gullies or rainforests. A rather drought tolerant species often found at exposed sites ranging from coastal to montane areas. Forming extensive, interwoven and creeping patches with its thin long (creeping) rhizomes sparsely covered in red-brown hairs, easily recognised by its membranous grey-green fronds, the smooth margins of the pinnae, ultimate segments and indusia; and by the sunken sori in the uppermost segments of the uppermost pinnae. The species can be found throughout Tasmanian rainforests as well as occurring in New South Wales, Victoria and New Zealand on the North and South Islands as well as, Stewart, Chatham and Auckland Islands.