Christella dentata (soft fern)

Pictures

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Picture

Title

Caption

Copyright

Habit and habitat

Christella dentata (soft fern, downy wood fern); habit and habitat. Honokowai Ditch Trail, Maui. June 21, 2010.

©Forest & Kim Starr Images-2010. CC-BY-3.0

Habit on bridge

Christella dentata (soft fern, downy wood fern); habit on bridge - many plants growing, in a line, below bridge parapet. Puaa Kaa Park, Hana Hwy, Maui. July 02, 2009

©Forest & Kim Starr Images-2009. CC-BY-3.0

Habit

Christella dentata (soft fern, downy wood fern); habit. Waihee Ridge Trail, Maui. September 25, 2002

©Forest & Kim Starr Images-2002. CC-BY-3.0

Fronds and habit

Christella dentata (dsoft fern, owny wood fern); fronds and habit. Garden of Eden Keanae, Maui. March 30, 2011

©Forest & Kim Starr Images-2011. CC-BY-3.0

Sori

Christella dentata (soft fern, downy wood fern); sori. Sacred Garden of Maliko, Maui. January 24, 2011

©Forest & Kim Starr Images-2011. CC-BY-3.0

Close-up of sori

Christella dentata (soft fern, downy wood fern); sori. Sacred Garden of Maliko, Maui. January 24, 2011

©Forest & Kim Starr Images-2011. CC-BY-3.0

Hybrid habit

Cyclosorus x intermedia (hybrid christella); habit. Makawao Forest Reserve, Maui. April 05, 2003

©Forest & Kim Starr Images-2003. CC-BY-3.0

Pinnules and sori

Cyclosorus x intermedia (hybrid christella); pinnules and sori. Makawao Forest Reserve, Maui. April 05, 2003

©Forest & Kim Starr Images-2003. CC-BY-3.0

Identity

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Preferred Scientific Name

Christella dentata (Forssk.) Holttum

Preferred Common Name

soft fern

Other Scientific Names

Aspidium molle Sw., J. Bot. (Schrader) 1800: 34 (1801)
Aspidium nymphale (G. Forst) Schkuhr (1804)
Christella dentata var. caespitosa Holttum (1986)
Cyclosorus dentatus (Forssk.) Ching
Cyclosorus nymphale (G. Forst) Ching (1941)
Cyclosourus nymphalis (G.Forst.) Ching
Dryopteris dentata (Forssk.) C. Chr. (1920)
Dryopteris molle (Sw.) Hieron (1907)
Dryopteris nymphalis (G. Forst.) Copel., 59:46 (1929 [1929])
Nephrodium dentatum (Forssk.) Kümmerle
Nephrodium molle (Sw.) R.Br. (1810)
Nephrodium nymphale (G. Forst) Desv. (1827)
Nephrodium remotum Heward (1842)
Polypodium dentatum Forssk (1775)
Polypodium molle Jacq. (1791)
Polypodium nymphale G. Forst. (1786)
Thelypteris dentata (Forssk.) E.P. St. John
Thylepteris nymphalis (G. Forst) C. F. Reed (1968)

International Common Names

English: downy maiden fern; downy shield fern; downy wood fern; tapering tri-vein fern
Spanish: helecha

Local Common Names

Cuba: helecho

Summary of Invasiveness

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C. dentata is a small fern widespread throughout the tropics and appears to be introduced in Hawaii and the Americas, where it was collected for the first time only relatively recently, having probably established prior to 1900 (Strother and Smith, 1970; Wagner, 1972). Elsewhere in the Pacific it is well established but its status as an introduced species is debated. With long distance dispersal (100s of kilometers) being possible via dispersal of its spores, it is believed to have arrived in New Zealand under its own volition.

Throughout its range it has a tendency to hybridize with other congeners, including other weeds like C. parasitica (=Cyclosorus parasiticus) in Guam, Hawaii and Taiwan, and the endemic C. cyatheoides in Hawaii, and even species from other genera such as Pneumatopteris afra (Fosberg and Sachet 1981; Quansah and Edwards 1986; Palmer 2003). In addition it can be difficult to tell C. dentata apart from some other congeners (Wagner 1950; Brownlie 1959; Lange et al. 1999).

In Hawaii it can form dense stands in disturbed sites, where it can outcompete some native species (J Beachy, US Fish and Wildlife Service, personal communication, 2010a, 2010b, 2010c). It can be an early colonizer after invasive pigs disturb a site (C Buddenhagen, Florida State University, personal observation).

C. dentata is not invasive in New Zealand. Of the two forms present (see Biology and Ecology), the 'true' form occurs only in a few very restricted places in northern New Zealand and is very rare. The thermal form, although more abundant, shows no sign of spreading out from its specialized habitat to other parts of the country. In New Zealand the 'true' C. dentata is regarded as 'Nationally Critical', whilst the other form is deemed 'At Risk'.

Taxonomic Tree

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Domain: Eukaryota
Kingdom: Plantae
Phylum: Pteridophyta
Class: Filicopsida
Family: Thelypteridaceae
Genus: Christella
Species: Christella dentata

Notes on Taxonomy and Nomenclature

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Christella dentata (Forssk.) Brownsey & Jermy has been in use for this species since 1973, and much of the existing literature refers to this name (Brownsey and Jermy, 1973). However, in North America and elsewhere Thelypteris dentata (Forssk.) E.P. St. John is still applied to this taxon (USDA, 2012).

It appears though that the genus Christella Léveillé is not monophyletic, and is best subsumed within Cyclosorus, making Cyclosorus dentatus (Forssk.) Ching the preferred name under modern systematic standards (Smith et al., 2006; Evenhuis and Eldredge, 2011; He and Zhang, 2012). All these names are derived from the basionym: Polypodium dentatum Forsskål 1775.

Several common characters exhibit continuous variation across generic boundaries in the clade containing Christella, and some taxa currently within Christella are polyphyletic (He and Zhang, 2012). Christella could be made monophyletic if the few taxa that are polyphyletic were dropped and placed elsewhere; such a decision may be justifiable on the basis of morphological and or molecular (DNA) differences (He and Zhang, 2012). It is worth noting that the type specimen (from Yemen) is unhelpful because it consists of a single portion of the middle of a frond, and so does not show the critical features people traditionally use to define the species (P de Lange, personal communication). Unless this is resolved, understanding when a Christella specimen is naturalized or indigenous anywhere in the Pacific or New World where that name is used is likely to be difficult (Brownlie, 1959).

Given the possibility of Christella becoming monophyletic again, and in view of the fact that The Plant List (2013) lists Christella dentata as a preferred name and Cyclosorus dentatus as a synonym, this datasheet uses the name Christella dentata as the preferred scientific name.

Description

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Stems short-creeping, 4-6 mm in diameter. Leaves often somewhat dimorphic, evergreen, often closely placed, 50-150 cm, fertile, with longer petioles and more contracted pinnae. Petiole often purplish brown, 15-50 cm by 3-6 mm at the base with brown, linear-lanceolate, hairy scales. Blade (25-) 40-100 cm, 1-4(-6) proximal pairs of pinnae reduced, blade gradually tapered to pinnatifid apex. Pinnae 7-17 by 1-3 cm, incised 1/2-3/4 of width; segments rounded at apex, basal acroscopic segment of proximal pinnae often auriculate; proximal pair of veins from adjacent segments united at obtuse angle below sinus with excurrent vein 2-4 mm. Indument abaxially of uniformly short hairs 0.1-0.2 mm on costae, veins, and blade tissue; veins adaxially with stouter hairs, also with hairs 0.1-0.2 mm on blade tissue. Sori round, medial to supramedial; indusia tan, pubescent, hairs 0.1-0.3 mm; sporangial stalks with orangish, stalked glands (Flora of North America, 1993).

Plant Type

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Herbaceous
Perennial

Distribution

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C. dentata is native to the Old World tropics (widespread in Asia and Africa) and temperate parts of Australia and New Zealand (McCarthy, 1998), but is adventive in North and Central America. It has been described as having a tropical cosmopolitan distribution (Iwatsuki, 1963), but it also occurs in subtropical sites that are frost-free or nearly so, perhaps surviving a few frosts a year in northern Florida (GBIF, 2012).

C. dentata was first recorded in Japan in the 1950s and has since spread northward (possibly as a greenhouse contaminant) at a rate of 3 km per year, persisting through the winters probably as a result of urban heat islands (Murakami et al., 2007). In Hawaii the species was collected much earlier and was probably introduced in and established by the late 1800s (MacCaughey, 1918; Wagner, 1950).

It is not clear whether the two forms of C. dentata present in New Zealand (see Biology and Ecology) arrived within historic time or whether they have been established there rather longer, although the species was recorded early in the country's history, so it seems unlikely to have been introduced (P Brownsey, Museum of New Zealand, personal communication). There is similar uncertainty over C. dentata in Fiji.

C. dentata is regarded as native in Lord Howe Island, Norfolk Island, Tonga and Tahiti, although one publication suggests it is introduced in Tahiti (Iwatsuki 1963; Rodd and Pickard 1983; Murdock and Smith 2003; Orchard, 1994; Meyer et al., 2009). It has also been recorded from New Caledonia, Vanuatu, Samoa and the Cook Islands.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Last updated: 17 Dec 2021

Continent/Country/Region	Distribution	Origin	First Reported	Invasive	Reference	Notes
Africa
Angola	Present	Native			GBIF (2012)
Benin	Present	Native			GBIF (2012)	Atacora
Burkina Faso	Present	Native			GBIF (2012)
Burundi	Present, Widespread	Native			GBIF (2012)	Bubanza Bururi
Cabo Verde	Present	Native			Porter (1987)
Cameroon	Present	Native			GBIF (2012)
Central African Republic	Present	Native			GBIF (2012)
Comoros	Present	Native			GBIF (2012)
Congo, Democratic Republic of the	Present	Native			Léonard (1994) GBIF (2012)
Congo, Republic of the	Present	Native			Joncheere (1960) GBIF (2012)
Côte d'Ivoire	Present, Widespread	Native			GBIF (2012) Tuo et al. (2013)
Equatorial Guinea	Present	Native			GBIF (2012)
Eswatini	Present, Localized	Native			GBIF (2012)
Ethiopia	Present	Native			GBIF (2012)
Gabon	Present, Widespread	Native			GBIF (2012)
Ghana	Present, Widespread	Native			GBIF (2012)
Kenya	Present, Widespread	Native			GBIF (2012)
Liberia	Present	Native			GBIF (2012)
Madagascar	Present, Widespread	Native			GBIF (2012)
Mayotte	Present	Native			GBIF (2012)
Morocco	Present	Native			GBIF (2012)
Mozambique	Present	Native			Silva et al. (2004)
Rwanda	Present	Native			GBIF (2012)
Senegal	Present	Native			GBIF (2012)
Sierra Leone	Present	Native			GBIF (2012)
South Africa	Present, Widespread	Native			GBIF (2012)	Eastern Cape
Tanzania	Present, Widespread	Native			GBIF (2012)
Togo	Present, Localized	Native			GBIF (2012)
Uganda	Present, Widespread	Native			GBIF (2012)
Zambia	Present	Native			GBIF (2012)
Zimbabwe	Present	Native			GBIF (2012)
Asia
China	Present				CABI (Undated a)	Present based on regional distribution.
-Yunnan	Present	Native			GBIF (2012)
India	Present				CABI (Undated a) Haldar and Ray (2011)	Present based on regional distribution.
-Himachal Pradesh	Present, Few occurrences	Native			Schelpe (1954)	Growing in ditches in towns and farmland, Beas River.
-Uttarakhand	Present	Native			GBIF (2012)
-West Bengal	Present				Haldar and Ray (2011)
Indonesia	Present, Widespread	Native			GBIF (2012)
Japan	Present, Localized	Introduced		Invasive	Murakami et al. (2007) GBIF (2012) Seebens et al. (2017)	Nara, Kochi, Wakayama, Kinki; First reported: 1950s
Malaysia	Present	Native			GBIF (2012)
Philippines	Present, Widespread	Native			GBIF (2012)
Singapore	Present	Native			GBIF (2012)
Thailand	Present	Native			Tagawa and Iwatsuki (1965) GBIF (2012)
Yemen	Present	Native			GBIF (2012)	Also the type specimen for the species is from here.
Europe
Greece	Present				CABI (Undated a)	Present based on regional distribution.
-Crete	Present				Brownsey and Jermy (1973)
Italy	Present	Introduced	2017		Seebens et al. (2017)
Portugal	Present	Native			GBIF (2012)
-Azores	Present	Introduced	1844		Seebens et al. (2017)
Spain	Present	Native			GBIF (2012)
-Canary Islands	Present, Widespread	Native			Velazquez (2005) GBIF (2012)
North America
Antigua and Barbuda	Present	Introduced			GBIF (2012)
Belize	Present, Widespread	Introduced			GBIF (2012)
Costa Rica	Present, Widespread	Introduced			GBIF (2012)
Cuba	Present	Introduced		Invasive	Oviedo Prieto et al. (2012) GBIF (2012) Seebens et al. (2017)
Dominica	Present, Widespread	Introduced			GBIF (2012)
Dominican Republic	Present, Widespread	Introduced			GBIF (2012)
El Salvador	Present, Widespread	Introduced			GBIF (2012)
Guatemala	Present, Widespread	Introduced			GBIF (2012)
Honduras	Present, Widespread	Introduced			GBIF (2012)
Mexico	Present, Localized	Introduced			GBIF (2012)
Nicaragua	Present, Widespread	Introduced			GBIF (2012)
Panama	Present, Widespread	Introduced			GBIF (2012)
Trinidad and Tobago	Present	Introduced	1897		Seebens et al. (2017)
United States	Present				CABI (Undated a) Seebens et al. (2017)	Present based on regional distribution.
-Alabama	Present, Localized	Introduced			GBIF (2012)
-Arkansas	Present, Localized	Introduced			GBIF (2012)
-Florida	Present, Widespread	Introduced			St John (1936) Bartsch and Lawrence (1997) GBIF (2012)
-Georgia	Present, Localized	Introduced			Norsworthy (1966) Faircloth (1975) GBIF (2012)
-Hawaii	Present	Introduced	1887		Seebens et al. (2017)
-Kentucky	Present	Introduced			GBIF (2012)
-Louisiana	Present, Localized	Introduced			GBIF (2012)
-Mississippi	Present, Localized	Introduced			GBIF (2012)
-South Carolina	Absent, Formerly present				Hill (1992)	Reported as a native species
-Texas	Present, Localized	Introduced			GBIF (2012)
Oceania
American Samoa	Present	Native			Whistler (1998)
Australia	Present, Widespread	Native			Rodd and Pickard (1983) CABI (Undated)	Including Lord Howe Island
-New South Wales	Present, Widespread	Native			GBIF (2012)
-Northern Territory	Present, Localized	Native			GBIF (2012)
-Queensland	Present, Widespread	Native			GBIF (2012)
-South Australia	Present, Few occurrences	Native			GBIF (2012)
-Victoria	Present, Few occurrences	Native			GBIF (2012)
-Western Australia	Present, Few occurrences	Native			GBIF (2012)
Fiji	Present	Native			Brownsey and Perrie (2011)
French Polynesia	Present	Native			Murdock and Smith (2003)	Recent studies say it is native
Guam	Present	Native			Stone (1971) Fosberg and Sachet (1981)
New Zealand	Present, Few occurrences	Native			Brownsey and Smith-Dodsworth (1989) Lange et al. (1999) GBIF (2012) CABI (Undated)	Raoul Islands, Northern North Island, Geothermal sites in the Waikato
Norfolk Island	Present	Native			GBIF (2012)
Papua New Guinea	Present	Native			GBIF (2012)
Tonga	Present	Native			Iwatsuki (1963)
South America
Argentina	Present	Introduced			GBIF (2012)
Bolivia	Present	Introduced			GBIF (2012)	Chuquisaca, Cochabamba, La Paz, Santa Cruz
Brazil	Present				CABI (Undated a) Mesquita et al. (2013)	Present based on regional distribution.
-Goias	Present	Introduced			GBIF (2012)
-Maranhao	Present				Mesquita et al. (2013)
-Mato Grosso do Sul	Present	Introduced			GBIF (2012)
-Minas Gerais	Present	Introduced			GBIF (2012)
-Parana	Present	Introduced			GBIF (2012)
-Sao Paulo	Present	Introduced			GBIF (2012)
Chile	Present	Native			GBIF (2012)
Colombia	Present, Widespread	Native			GBIF (2012)
Ecuador	Present, Widespread	Native			GBIF (2012)
Paraguay	Present, Widespread	Native			GBIF (2012)
Peru	Present, Localized	Native			GBIF (2012)
Venezuela	Present, Widespread	Introduced			GBIF (2012)

History of Introduction and Spread

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C. dentata is native to the Old World tropics (widespread in Asia and Africa) and temperate parts of Australia and New Zealand (McCarthy, 1998), but is adventive in the Americas, where it was most likely introduced around 1900 as a greenhouse contaminant (Strother and Smith, 1970; Holttum, 1976; Smith, 1993). It has been described as having a tropical cosmopolitan distribution (Iwatsuki, 1963), but it also occurs in subtropical sites that are frost-free or nearly so, perhaps surviving a few frosts a year in northern Florida (GBIF, 2012). Specimens of this plant were not collected in the New World (e.g. Brazil, Florida) prior to the 1930s, and in some cases only after the 1940-1950s (e.g. Costa Rica and Hispaniola) (Strother and Smith, 1970).

C. dentata was first recorded in Japan in the 1950s and has since spread northward (possibly as a greenhouse contaminant) at a rate of 3 km per year, persisting through the winters probably as a result of urban heat islands (Murakami et al., 2007). In Hawaii the species was collected much earlier and was probably introduced in and established by the late 1800s (MacCaughey, 1918; Wagner, 1950).

It is not clear whether the two forms of C. dentata present in New Zealand (see Biology and Ecology) arrived within historic time or whether they have been established there rather longer, although the species was recorded early in the country's history, so it seems unlikely to have been introduced (P Brownsey, Museum of New Zealand, personal communication). There is similar uncertainty over C. dentata in Fiji.

C. dentata is regarded as native in Lord Howe Island, Norfolk Island, Tonga and Tahiti, although one publication suggests it is introduced in Tahiti (Iwatsuki 1963; Rodd and Pickard 1983; Murdock and Smith 2003; Orchard, 1994; Meyer et al., 2009).

Risk of Introduction

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C. dentata is an effective disperser that has reached some Pacific islands (e.g. New Zealand, Fiji, Raoul and Norfolk Islands) probably via natural means (Brownsey and Smith-Dodsworth, 1989; Wolf et al., 2001).

Its presence in Hawaii and the Americas is likely to be the result of accidental introduction (Strother and Smith 1970). The most probable human-mediated pathway for this plant’s introduction is accidentally via the horticultural trade. However, C. dentata is rarely traded as an ornamental plant now (Ko et al., 1997).

Habitat

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C. dentata is regarded as a facultative wetland plant. Both in its native and introduced ranges forested wetlands, damp woods and disturbed or open wet areas are typical habitats (Viane 1985; Flora of North America Editorial Committee 1993; USDA 2012). In Hawaiian forests it has colonized trails and road sides, weedy gulches and areas disturbed by pigs (C Buddenhagen, Florida State University, personal communication). In general it grows well in disturbed, wet sites. It often co-occurs with another widespread adventive fern, C. parasitica (=Cyclosorus parasiticus).

It is tolerant of a range of soil conditions, although it has been suggested as an indicator of calcareous conditions in South Carolina (Hill 1992) and has been found on limestone substrates in the Bahamas (Correll 1976). C. dentata can tolerate some shade.

Fronds of C. dentata are killed by exposure to -3 degrees Celsius for 2 hours or more (Given 1980). Frosts seem to limit the range of this species, although occasional frosts may be tolerated considering that it has been found growing in Kyoto (Japan) and South Carolina and Georgia (USA) (Norsworthy, 1966; Faircloth, 1975; Hill, 1992; Murakami et al., 2007; GBIF, 2012; USDA, 2012). In New Zealand C. dentata occurs in geothermal sites (Lange et al. 1999).

Habitat List

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Category	Sub-Category	Habitat	Presence	Status
Terrestrial	Managed	Cultivated / agricultural land	Present, no further details
Terrestrial	Managed	Protected agriculture (e.g. glasshouse production)	Present, no further details	Harmful (pest or invasive)
Terrestrial	Managed	Managed forests, plantations and orchards	Present, no further details	Natural
Terrestrial	Managed	Disturbed areas	Principal habitat
Terrestrial	Managed	Urban / peri-urban areas	Principal habitat	Harmful (pest or invasive)
Terrestrial	Natural / Semi-natural	Natural forests	Principal habitat	Harmful (pest or invasive)
Terrestrial	Natural / Semi-natural	Wetlands	Principal habitat	Harmful (pest or invasive)

Host Plants and Other Plants Affected

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Plant name	Family	Context	References
Ananas comosus (pineapple)	Bromeliaceae	Main
Hevea brasiliensis (rubber)	Euphorbiaceae	Unknown	Tuo et al. (2013)
Oryza sativa (rice)	Poaceae	Unknown	Mesquita et al. (2013)

Biology and Ecology

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Genetics

2 n = 144 (Flora of North America, 1993).

For other chromosome counts see Löve et al. (1977). There is also evidence of polyploidy in C. dentata.

Diversity

There are believed to be two forms in New Zealand: one is the true C. dentata, with a long-creeping rhizome and which occurs only in a couple of places in the northern North Island (and is also reasonably common on Raoul Island and Norfolk islands) (P Brownsey, Museum of New Zealand, personal communication). The other has an erect or short-creeping rhizome and occurs around thermal areas and also on Raoul Island (although occurs less commonly there than true C. dentata) (Brownsey and Smith-Dodsworth, 1989). The relationship between these two forms and whether they are both attributable to C. dentata remains to be determined.

Climate

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Climate	Status	Description
A - Tropical/Megathermal climate	Preferred	Average temp. of coolest month > 18°C, > 1500mm precipitation annually
Af - Tropical rainforest climate	Preferred	> 60mm precipitation per month
Am - Tropical monsoon climate	Preferred	Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
C - Temperate/Mesothermal climate	Tolerated	Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C
Cf - Warm temperate climate, wet all year	Tolerated	Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cw - Warm temperate climate with dry winter	Tolerated	Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)

Latitude/Altitude Ranges

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Latitude North (°N)	Latitude South (°S)	Altitude Lower (m)	Altitude Upper (m)
35	38

Air Temperature

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Parameter	Lower limit	Upper limit
Mean annual temperature (ºC)	0

Soil Tolerances

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Soil drainage

free
impeded
seasonally waterlogged

Soil reaction

alkaline
neutral

Soil texture

light
medium

Means of Movement and Dispersal

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Occasional long-distance dispersal (100s of kilometers) from Australia or elsewhere has been suggested as an explanation for C. dentata occurrences in New Zealand and South Pacific islands (Given, 1980; McGlone et al., 2001).

Its presence in Hawaii and the Americas is probably the result of accidental introduction (Strother and Smith, 1970). The most likely human-mediated pathway for this plant’s introduction is accidentally via the horticultural trade.

Spores and gametophytes could easily be transported and are likely contaminants of nurseries, greenhouses, house plants and the potted plant trade, provided the climate is suitable.

Pathway Causes

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Cause	Notes	Long Distance	References
Disturbance	Colonizes disturbed gullies, trailsides and areas frequented by pigs. For references, please see te	Yes
Escape from confinement or garden escape	This is not an example of an escape but the planting of it as an ornamental	Yes	Drummond (1959)
Flooding and other natural disasters	As a facultative wetland plant one could imagine its spread by this means.	Yes	USDA-NRCS (2012)
Garden waste disposal	Weed of urban areas	Yes	CSIRO (1998); Randall (2002); Randall (2009)
Hitchhiker	Spores and gametophytes could be easily transported	Yes
Horticulture	Associated with greenhouse cultivation	Yes	Drummond (1959); Murakami et al. (2007); Strother and Smith (1970); Wagner (1950)
Ornamental purposes	Attractive ferns such as this could be spread intentionally in some cases.	Yes	Drummond (1959)

Pathway Vectors

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Vector	Notes	Long Distance	Local	References
Plants or parts of plants	Unknown speculated about in the literature.	Yes	Yes	Murakami et al. (2007); Strother and Smith (1970); Wagner (1950); Wagner (1972)

Impact Summary

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Category	Impact
Environment (generally)	Negative

Threatened Species

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Threatened Species	Conservation Status	Where Threatened	Mechanism	References
Poa mannii (Mann's bluegrass)	CR (IUCN red list: Critically endangered); USA ESA listing as endangered species	Hawaii	Competition	US Fish and Wildlife Service (2010b)
Pritchardia napaliensis	CR (IUCN red list: Critically endangered); USA ESA listing as endangered species	Hawaii	Competition	US Fish and Wildlife Service (2010a)
Remya montgomeryi (Kalalau Valley remya)	CR (IUCN red list: Critically endangered); USA ESA listing as endangered species	Hawaii	Competition	US Fish and Wildlife Service (2010d)
Schiedea apokremnos (Kauai schiedea)	CR (IUCN red list: Critically endangered); USA ESA listing as endangered species	Hawaii	Competition	US Fish and Wildlife Service (2010c)

Risk and Impact Factors

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Invasiveness

Invasive in its native range
Proved invasive outside its native range
Has a broad native range
Abundant in its native range
Highly adaptable to different environments
Is a habitat generalist
Pioneering in disturbed areas
Tolerant of shade
Highly mobile locally
Long lived
Has high reproductive potential
Reproduces asexually

Impact outcomes

Damaged ecosystem services
Ecosystem change/ habitat alteration
Modification of successional patterns
Monoculture formation
Reduced native biodiversity
Threat to/ loss of endangered species
Threat to/ loss of native species

Impact mechanisms

Competition - monopolizing resources
Competition - shading
Competition - smothering
Hybridization
Interaction with other invasive species

Likelihood of entry/control

Highly likely to be transported internationally accidentally
Difficult to identify/detect as a commodity contaminant
Difficult to identify/detect in the field

Uses List

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General

Botanical garden/zoo

Detection and Inspection

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This species is easily confused with C. parasitica (=Cyclosorus parasiticus)(Wagner 1950). Living plants of C. parasitica are paler, with a duller green, and its proximal pinnae are narrower. Most importantly, its fronds are not dimorphic and they do not have the sharp break between sterile and fertile fronds that C. dentata has. C. dentata’s sterile fronds are broader, shorter, more spreading than the others and generally entirely without sori.

Similarities to Other Species/Conditions

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This species is easily confused with C. parasitica (=Cyclosorus parasiticus) (Wagner, 1950). Living plants of C. parasitica are paler and a duller green, and have narrower proximal pinnae. Most importantly, its fronds are not dimorphic and do not have the sharp break between sterile and fertile fronds that C. dentata has. C. dentata’s sterile fronds are broader, shorter, and more spreading than the others, and generally entirely without sori.

A key to Chinese species of the subgenus Cyclosoriopsis (including both Cyclosorus parasiticus and Christella dentata) is provided by Li et al. (2013).

Prevention and Control

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Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

With long-distance dispersal (100s of kilometers) being possible via the dispersal of spores, as evidenced from its likely unassisted arrival to New Zealand and other South Pacific Islands, this is a species that may be difficult or impossible to contain once established in a region.

Hand weeding or treatment with herbicide have been used to control C. dentata. The application of triclopyr at standard foliar rates or at high concentrations with biodiesel to the rhizome has been shown to work (J Beachy, US Fish and Wildlife Service, personal communication).

Gaps in Knowledge/Research Needs

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More could be done to understand the history of the spread of this species around the world, in both its introduced and its native range. The genetic connectivity between populations could tell us more about this species’ spread in short- and long-term evolutionary timeframes.

References

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Bartsch I; Lawrence J, 1997. Leaf Size and Biomass Allocation in Thelypteris Dentata, Woodwardia Virginica and Osmunda Regalis in Central Florida. Leaf Size and Biomass Allocation in Thelypteris Dentata, Woodwardia Virginica and Osmunda Regalis. American Fern Journal:71-76.

Brownlie G, 1959. Some Problems in New Zealand Fern Nomenclature. Transactions of the Royal Society in New Zealand, 87:195-198.

Brownsey PJ; Jermy AC, 1973. A Fern Collection Expedition to Crete. The British Fern Gazette, 10(6):331-348.

Brownsey PJ; Perrie LR, 2011. A revised Checklist of Fijian ferns and lycophytes. Telopea, 13:513-562.

Brownsey PJ; Smith-Dodsworth JC, 1989. New Zealand ferns and allied plants. Auckland, New Zealand: David Bateman Ltd., viii + 168 pp.

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Drummond WC, 1959. The Fern Dell, Los Angeles. American Fern Journal:2-9.

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Evenhuis NL; Eldredge LG, 2011. Taxonomic Changes in Hawaiian Ferns and Lycophytes. Bishop Museum Occasional Papers, 110:11-16.

Faircloth WR, 1975. Ferns and Other Primitive Vascular Plants of Central South Georgia. Castanea 40(3):217-228.

Fish and Wildlife Service US, 2010. Lo`ulu (Pritchardia napaliensis) 5-Year Review. A Status Review to Determine If They Are Appropriately Listed Under the U. Endangered Species Act. Lo`ulu (Pritchardia napaliensis) 5-Year Review. Honolulu, Hawaii, USA: Department of Interior, Fish and Wildlife Service. http://ecos.fws.gov/docs/five_year_review/doc3317.pdf

Fish and Wildlife Service US, 2010. Schiedea apokremnos (maolioli) 5-Year Review. A Status Review to Determine If They Are Appropriately Listed Under the U. Endangered Species Act. Schiedea apokremnos (maolioli) 5-Year Review. Honolulu, Hawaii, USA: US Fish and Wildlife Service. http://ecos.fws.gov/docs/five_year_review/doc3319.pdf

Fish and Wildlife Service US2, 2010. Remya montgomeryi (5-Year Review). A Status Review to Determine if They Are Appropriately Listed Under the U. Endangered Species Act. Remya montgomeryi (5-Year Review). Honolulu, Hawaii, USA: US Fish and Wildlife Service. http://ecos.fws.gov/docs/five_year_review/doc3343.pdf

Fosberg FR; Sachet MH, 1981. Nomenclatural Notes on Micronesian Ferns. American Fern Journal 71(3):82-84.

GBIF, 2012. Global Biodiversity Information Facility. Global Biodiversity Information Facility (GBIF). http://data.gbif.org

Given D, 1980. Vegetation on Heated Soils at Karapiti, Central North Island, New Zealand, and Its Relation to Ground. Vegetation on Heated Soils at Karapiti, Central North Island, New Zealand. Nwe Zealand Journal of Botany 18(1):1-13.

Grayum MH; Churchill HW, 1987. An Introduction to the Pteridophyte Flora of Finca La Selva, Costa Rica. American Fern Journal 77(3):73-89.

He LJ; Zhang XC, 2012. Exploring Generic Delimitation Within the Fern Family Thelypteridaceae. Molecular Phylogenetics and Evolution 65(2):757-764.

Hill SR, 1992. Calciphiles and Calcareous Habitats of South Carolina. Castanea 57(1):25-33.

Holttum RE, 1976. The Genus Christella Leveille, Sect. The Genus Christella Leveille. Kew Bulletin 31(2), Sect:293-339. [Christella Studies in the Family Thelypteridaceae, XI.]

Iwatsuki K, 1963. New or Noteworthy Ferns from the Tonga Islands. American Fern Journal 53(4):133-138.

Joncheere GJ de, 1960. Ferns in Oubangi, Congo. American Fern Journal 50(3):228-231.

Ko MP; Schmitt DP; Saxby M, 1997. Effects of container bases on the spread of Meloidogyne incognita in a Hawaiian ornamental nursery. Plant Disease, 81(6):607-613.

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Lange PJ de; Heenan PB; Given DR; Norton DA; Ogle CC; Johnson PN; Cameron EK, 1999. Threatened and uncommon plants of New Zealand. New Zealand Journal of Botany, 37(4):603-628.

Leonard J, 1994. Periodically flooded vegetation of the sandstone cliffs of the Yanonge (Yangambi-Kisangani, Zaire) (La vegetation periodiquement inondee des falaises greseuses de Yanonge (Yangambi-Kisangani, Zaire)). Bulletin of the National Botanical Garden of Belgium 63(1):101-123.

Li ZY; He ZR; Zhang XC, 2013. A taxonomic revision of Cyclosorus subgenus Cyclosoriopsis (Thelypteridaceae) from China. Journal of Systematics and Evolution, 51(5):609-638. http://dx.doi.org/10.1111/jse.12013

Love A; Love D; Pichi Sermolli REG, 1977. Cytotaxonomical atlas of the Pteridophyta. J Cramer Publishing, 398 pp.

MacCaughey V, 1918. An Ecological Survey of the Hawaiian Pteridophytes. Journal of Ecology 6(3):199-219.

Mascaro J; Becklund KK; Hughes RF; Schnitzer SA, 2008. Limited native plant regeneration in novel, exotic-dominated forests on Hawai'i. Forest Ecology and Management, 256(4):593-606. http://www.sciencedirect.com/science/journal/03781127

McCarthy PM, 1998. Flora of Australia. Volume 48: Ferns, gymnosperms and allied groups. Flora of Australia. Volume 48: Ferns, gymnosperms and allied groups. Melbourne, Australia: ABRS/CSIRO Australia, xxi + 766 pp.

McGlone MS; Duncan RP; Heenan PB, 2001. Endemism, species selection and the origin and distribution of the vascular plant flora of New Zealand. Journal of Biogeography [Historical biogeography and patterns of diversity. XVI International Botanical Congress, St Louis, USA, August 1999.], 28(2):199-216.

Mesquita, M. L. R., Andrade, L. A. de, Pereira, W. E., 2013. Floristic diversity of the soil weed seed bank in a rice-growing area of Brazil: in situ and ex situ evaluation. Acta Botanica Brasilica, 27(3), 465-471. doi: 10.1590/S0102-33062013000300001

Meyer JY; Fourdrigniez M; Taputuarai R, 2009. Evaluation of terrestrial biodiversity of the island of Me'eti'a (Society archipelago) (Evaluation de la biodiversite terrestre de l'ile de Me'eti'a (archipel de la Societe). Contribution a la Biodiversite de Polynesie francaise N18. Sites Naturels d'Interet Ecologique et Patrimonial VII). Paris, France: Ministry of Education, Higher Education, Research and Culture.

Murakami K; Matsui R; Morimoto Y, 2007. Northward invasion and range expansion of the invasive fern Thelypteris dentata (Forssk.) St. John into the urban matrix of three prefectures in Kinki District, Japan. American Fern Journal, 97(4):186-198. http://www.bioone.org/bioone/?request=get-archive&issn=0002-8444

Murdock AG; Smith AR, 2003. Pteridophytes of Moorea, French Polynesia, with a new species, Tmesipteris gracilis (Psilotaceae). Pacific Science, 57(3):253-265.

Nair VD; Bissett NJ; Portier KM; Graetz DA; Segal DS; Garren RA, 2000. Soil conditions and plant establishment on reclaimed phosphate-mined uplands. Proceedings of the Seventeenth Annual Meeting of the American Society for Surface Mining and Reclamation: A New Era of Land Reclamation, 2000.

Norsworthy J, 1966. Fern Records for Echols County and the State of Georgia. American Fern Journal 56(2):55-57.

North America Flora of North America Editorial Committee, 1993. Flora of North America north of Mexico. Volume 2: Pteridophytes and Gymnosperms. New York, USA: Oxford University Press, xvi + 475 pp.

Orchard AE, 1994. Flora of Australia. Vol. 49, Oceanic islands 1. Canberra, Australia: Australian Government Publishing Service.

Oviedo Prieto R; Herrera Oliver P; Caluff MG, et al. , 2012. National list of invasive and potentially invasive plants in the Republic of Cuba - 2011. (Lista nacional de especies de plantas invasoras y potencialmente invasoras en la República de Cuba - 2011). Bissea: Boletín sobre Conservación de Plantas del Jardín Botánico Nacional de Cuba, 6(Special Issue 1):22-96.

Palmer DD, 2002. Taxonomic Notes on Hawaiian Pteridophytes. American Fern Journal 92(2):97-104.

Palmer DD, 2003. Hawaii's Ferns and Fern Allies. Honolulu, Hawaii, USA: University of Hawai'i Press.

Porter DM, 1987. Darwin notes on Beagle plants. Bulletin of the British Museum (Natural History):145-233.

Quansah N; Edwards DS, 1986. A Natural Bi-generic Fern Hybrid in Thelypteridaceae from Ghana. Kew Bulletin 41(4):805-809.

Randall RP, 2002. A Global Compendium of Weeds. Melbourne, Australia: RG & FJ Richardson.

Randall RP, 2009. The introduced flora of Australia and its weed status. CRC for Australian Weed Management. Glen Osmond, Australia: University of Adelaide. http://www.weedscrc.org.au/documents/intro_flora_australia.pdf

Rhymer JM; Simberloff D, 1996. Extinction by Hybridization and Introgression. Annual Review of Ecology and Systematics: 83-109.

Robinson RC, 2009. Invasive and Problem Ferns: a European Perspective. International Urban Ecology Review:83.

Rodd AN; Pickard J, 1983. Census of Vascular Flora of Lord Howe Island. Cunninghamia 1(2):267-280.

Schelpe E, 1954. Ecological Observations on Pteridophyta in the Kangra Himalaya. American Fern Journal:49-65.

Silva MC da; Izidine S; Amude AB, 2004. A preliminary checklist of the vascular plants of Mozambique. Pretoria, South Africa: South African Botanical Diversity Network.

Smith AR, 1993. Phytogeographic Principles and Their Use in Understanding Fern Relationships. Journal of Biogeography:255-264.

Smith AR; Pryer KM; Schuettpelz E; Korall P; Schneider H; Wolf PG, 2006. A Classification for Extant Ferns. Taxon 55(3):705-731.

Smith CW, 1985. Impact of alien plants on Hawaii's native biota. In: Hawaii's terrestrial ecosystems: preservation and management. Proceedings of a symposium held June 5-6, 1984, at Hawaii Volcanoes National Park. [ed. by Stone CP, Scott JM] Honolulu, HI, USA: University of Hawaii Press, 180-250.

St John EP, 1936. Rare ferns of central Florida. American Fern Journal 26(2):41-50.

Stone BC, 1971. The flora of Guam: A manual for the identification of the vascular plants of the island, 6. University of Guam, Guam: Micronesica, 659p.

Strother JL; Smith AR, 1970. Chorology, Collection Dates, and Taxonomic Responsibility. Taxon 19(6):871-874.

Tagawa M; Iwatsuki K, 1965. On a Small Collection of Thailand Ferns. Southeast Asian Studies 3:70-89.

The Plant List, 2013. The Plant List: a working list of all plant species. Version 1.1. London, UK: Royal Botanic Gardens, Kew. http://www.theplantlist.org

Tuo, K. F. A., Orega, Y. B., Kouame, K. B. J., Abo, K., Agneroh, T. A., 2013. Characterization of weed flora in rubber trees plantations of bongo (Côte d'ivoire). Journal of Applied Biosciences, 70, 5544-5554. http://m.elewa.org/JABS/2013/70/3.pdf

US Fish and Wildlife Service, 2010. 5-Year review. Short Form Summary Species Reviewed: Poa mannii (Mann's bluegrass). 5-Year review. Short Form Summary Species Reviewed: Poa mannii (Mann's bluegrass). 10 pp. http://ecos.fws.gov/docs/five_year_review/doc3296.pdf

USDA-NRCS, 2012. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/

Velazquez TS, 2005. Taxonomic key of the Pterifoflora of the Canary Islands (Clave taxonomica de la pteridoflora de las Islas Canarias). Botanica Complutensis, 28:39-50.

Viane RLL, 1985. A New Species and a New Hybrid of Thelypteris (Pteridophyta) from the Ivory Coast. Bulletin of the Royal Botanical Garden of Belgium:41-56.

Wagner WH, 1950. Ferns Naturalized in Hawaii. Occasional Papers of the Bishop Museum 20(8):95-120.

Wagner WH, 1972. Disjunctions in Homosporous Vascular Plants. Annals of the Missouri Botanical Garden 59(2):203-217.

Whistler WA, 1998. A study of the rare plants of American Samoa. Report prepared for the US Fish and Wildlife Service. A study of the rare plants of American Samoa, 1. Honolulu, USA: US Fish and Wildlife Service, 18.

Wolf PG; Schneider H; Ranker TA, 2001. Geographic Distributions of Homosporous Ferns: Does Dispersal Obscure Evidence of Vicariance? Geographic Distributions of Homosporous Ferns. Journal of Biogeography, 28(2):263-270.

Distribution References

Bartsch I, Lawrence J, 1997. Leaf Size and Biomass Allocation in Thelypteris Dentata, Woodwardia Virginica and Osmunda Regalis in Central Florida. In: American Fern Journal, 71-76.

Brownsey P J, Smith-Dodsworth J C, 1989. New Zealand ferns and allied plants. Auckland, New Zealand: David Bateman Ltd. viii + 168 pp.

Brownsey PJ, Jermy AC, 1973. A Fern Collection Expedition to Crete. In: The British Fern Gazette, 10 (6) 331-348.

Brownsey PJ, Perrie LR, 2011. A revised Checklist of Fijian ferns and lycophytes. In: Telopea, 13 513-562.

CABI, Undated. Compendium record. Wallingford, UK: CABI

CABI, Undated a. CABI Compendium: Status inferred from regional distribution. Wallingford, UK: CABI

CABI, Undated b. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI

Faircloth WR, 1975. Ferns and Other Primitive Vascular Plants of Central South Georgia. In: Castanea, 40 (3) 217-228.

Fosberg FR, Sachet MH, 1981. Nomenclatural Notes on Micronesian Ferns. In: American Fern Journal, 71 (3) 82-84.

GBIF, 2012. Global Biodiversity Information Facility. http://www.gbif.org/species

Haldar D, Ray J B, 2011. Studies on Cercospora like fungi of West Bengal-II. Journal of Mycopathological Research. 49 (1), 151-153. http://www.imskolkata.org/

Hill SR, 1992. Calciphiles and Calcareous Habitats of South Carolina. In: Castanea, 57 (1) 25-33.

Iwatsuki K, 1963. New or Noteworthy Ferns from the Tonga Islands. In: American Fern Journal, 53 (4) 133-138.

Joncheere GJ de, 1960. Ferns in Oubangi, Congo. In: American Fern Journal, 50 (3) 228-231.

Lange P J de, Heenan P B, Given D R, Norton D A, Ogle C C, Johnson P N, Cameron E K, 1999. Threatened and uncommon plants of New Zealand. New Zealand Journal of Botany. 37 (4), 603-628.

Léonard J, 1994. A revision of the genus Maesobotrya (Euphorbiaceae) in Zaire. (Révision des espèces zairoises du genre Maesobotrya Benth. (Euphorbiaceae).). Bulletin du Jardin Botanique National de Belgique. 63 (1/2), 3-67. DOI:10.2307/3668468

Mesquita M L R, Andrade L A de, Pereira W E, 2013. Floristic diversity of the soil weed seed bank in a rice-growing area of Brazil: in situ and ex situ evaluation. Acta Botanica Brasilica. 27 (3), 465-471. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062013000300001&lng=en&nrm=iso&tlng=en DOI:10.1590/S0102-33062013000300001

Murakami K, Matsui R, Morimoto Y, 2007. Northward invasion and range expansion of the invasive fern Thelypteris dentata (Forssk.) St. John into the urban matrix of three prefectures in Kinki District, Japan. American Fern Journal. 97 (4), 186-198. http://www.bioone.org/bioone/?request=get-archive&issn=0002-8444 DOI:10.1640/0002-8444(2007)97[186:NIAREO]2.0.CO;2

Murdock A G, Smith A R, 2003. Pteridophytes of Moorea, French Polynesia, with a new species, Tmesipteris gracilis (Psilotaceae). Pacific Science. 57 (3), 253-265. DOI:10.1353/psc.2003.0024

Norsworthy J, 1966. Fern Records for Echols County and the State of Georgia. In: American Fern Journal, 56 (2) 55-57.

Oviedo Prieto R, Herrera Oliver P, Caluff M G, et al, 2012. National list of invasive and potentially invasive plants in the Republic of Cuba - 2011. (Lista nacional de especies de plantas invasoras y potencialmente invasoras en la República de Cuba - 2011). Bissea: Boletín sobre Conservación de Plantas del Jardín Botánico Nacional de Cuba. 6 (Special Issue No. 1), 22-96.

Porter DM, 1987. Darwin notes on Beagle plants. In: Bulletin of the British Museum (Natural History), 145-233.

Rodd AN, Pickard J, 1983. Census of Vascular Flora of Lord Howe Island. In: Cunninghamia, 1 (2) 267-280.

Schelpe E, 1954. Ecological Observations on Pteridophyta in the Kangra Himalaya. In: American Fern Journal, 49-65.

Seebens H, Blackburn T M, Dyer E E, Genovesi P, Hulme P E, Jeschke J M, Pagad S, Pyšek P, Winter M, Arianoutsou M, Bacher S, Blasius B, Brundu G, Capinha C, Celesti-Grapow L, Dawson W, Dullinger S, Fuentes N, Jäger H, Kartesz J, Kenis M, Kreft H, Kühn I, Lenzner B, Liebhold A, Mosena A (et al), 2017. No saturation in the accumulation of alien species worldwide. Nature Communications. 8 (2), 14435. http://www.nature.com/articles/ncomms14435

Silva MC da, Izidine S, Amude AB, 2004. A preliminary checklist of the vascular plants of Mozambique., Pretoria, South Africa: South African Botanical Diversity Network.

St John EP, 1936. Rare ferns of central Florida. In: American Fern Journal, 26 (2) 41-50.

Stone BC, 1971. The flora of Guam: A manual for the identification of the vascular plants of the island., 6 Guam: University of Guam, Micronesica. 659.

Tagawa M, Iwatsuki K, 1965. On a Small Collection of Thailand Ferns. In: Southeast Asian Studies, 3 70-89.

Tuo K F A, Orega Y B, Kouame K B J, Abo K, Agneroh T A, 2013. Characterization of weed flora in rubber trees plantations of bongo (Côte d'ivoire). Journal of Applied Biosciences. 5544-5554. http://m.elewa.org/JABS/2013/70/3.pdf

Velazquez TS, 2005. Taxonomic key of the Pterifoflora of the Canary Islands. (Clave taxonomica de la pteridoflora de las Islas Canarias). In: Botanica Complutensis, 28 39-50.

Whistler WA, 1998. A study of the rare plants of American Samoa. In: Report prepared for the US Fish and Wildlife Service. A study of the rare plants of American Samoa, 1 Honolulu, USA: US Fish and Wildlife Service. 18.

Organizations

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USA: University of Hawaii UH, Manoa, Honolulu, http://www.hawaii.edu

USA: US Fish and Wildlife Service, http://www.fws.gov/

Contributors

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14/11/12 Original text by:

Buddenhagen CE, Florida State University, USA

Distribution Maps

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Datasheet

Christella dentata (soft fern)

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