Ceratopteris

Ceratopteris
	Ceratopteris cornuta in aquarium
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Division:	Polypodiophyta
Class:	Polypodiopsida
Order:	Polypodiales
Family:	Pteridaceae
Subfamily:	Parkerioideae
Genus:	Ceratopteris; Brongn.
Type species
	Ceratopteris thalictroides; (L.) Brongn.
Species
	See text
Synonyms
	Cryptogenis Richard 1823 ex Brongniart 1823; Ellebocarpus Kaulfuss 1824; Furcaria Desvaux 1827; Parkeria Hooker 1825; Teleozoma Brown 1823;

Ceratopteris is the only genus among homosporous ferns that is exclusively aquatic. It is pan-tropical and classified in the Parkerioideae subfamily of the family Pteridaceae.^[1]

Description

Erect aquatic or subaquatic ferns of moderate size. Rhizome short, fleshy, horizontal and ascending to erect, loosely rooted in the mud or +/- floating, radial, dictyostelic with numerous meristeles and medullary strands, young parts bearing thin, ovate, +/- cordate, clathrate scales. Fronds stipitate, the stipes fleshy, with numerous longitudinal air canals, abaxially rounded and ribbed, adaxially flattened, vascular bundles in a peripheral ring, one with each rib and several to the adaxial side, and several smaller medullary strands; lamina dimorphic, sterile fronds +/- spreading, 2–3-pinnatifid with broad membranous lobes, venation reticulate without included free veinlets, often with proliferous buds in the axils; fertile fronds erect, longer, narrower and more divided than the sterile, the lobes strongly recurved to completely cover the adiaxial surface, venation longitudinal, branching at the bases of the lobes. Sporangia solititary, scattered along the veins, exindusiate but protected by the continuous reflexed margin of the lamina, large, short-stalked, annulus broad, irregular, of 30–70 thickened cells, or lacking, containing 16 to 32 spores. Spores large, trilete, ribbed with irregular long meshes.^[2]

Taxonomy

Ceratopteris was long placed in the monogeneric family Parkeriaceae, thought to be unique because of its aquatic adaptations. However, recent genetic analysis has shown it to be clearly allied with Acrostichum in the subfamily Parkerioideae, within the family Pteridaceae.

At one time, some authorities recognized only one species; now some authorities recognize only four species. However, recent work by Masuyama and Watano has suggested that C. thalictroides actually consists of four cryptic species (thalictroides, froesii, gaudichaudii, oblongibloba).^[3]

Phylogeny

Nitta et al. 2022^[4] and Fern Tree of life^[5]

Ceratopteris

C. richardii Brongn. 1823 ("C-fern"; Triangle waterfern)

C. cornuta (P. Beauv.) Le Prieur 1830

C. chingii Yang & Yu 2022

C. chunii Yang 2022

C. shingii Yan & Zhang 2020

	C. pteridoides (Hook.) Hieron. 1905 (Floating antlerfern)

	C. thalictroides (L.) Brongn. 1821 (Water Sprite, Oriental water fern)

Other species:

Ceratopteris froesii Brade 1964
Ceratopteris gaudichaudii Brongn. 1821
Ceratopteris oblongiloba Masuyama & Watano 2010

Distribution and habitat

This widespread genus of four to six species inhabits the humid tropics.

Ceratopteris is also important in the study of pteridophytes and is a commonly used model organism for use in genomic studies, due to the ease and rapidity with which it can be grown in laboratories, as well as having well-characterized phenotypes. Patented strains of this plant have been developed.

Outcrossing and self-fertilization

A gametophyte is one of the two alternating multicellular phases of the fern life cycle. The gametophyte is haploid. The other stage is the diploid sporophyte. A gametophyte is a multicellular organism that develops from a haploid spore (that has one set of chromosomes). Ceratopteris thalictroides has two types of gametophytes with different sexual expression: these types are hermaphrodite and male.^[6] Hermaphroditic gametophytes have one or several archegonia and a few antheridia. Archegonia are multicellular structures of the gametophyte that produce and contain the ovum or female gamete. The corresponding male organ is the antheridium, a haploid organ producing and containing sperm. The second of the two types of gametophyte are male that produce only antheridia.

When Ceratopteris richardii ferns are grown alone they develop into hermaphrodites (with mainly female archegonia). However, plants that grow near established genetically identical individuals develop into males. The hermaphrodite secretes a pheromone (antheridiogen) that tells others nearby to be male.^[7] Thus when plants are near each other outcrossing is promoted. Self-fertilization predominates when there is no nearby partner.

Toxicity

The plants may have carcinogenic properties.^[8]

Uses

Ceratopteris is a fairly popular aquarium plant, often sold under the name "water sprite." It may be grown as an emersed but natant (floating) plant, or as an immersed plant rooted in the substrate. Under the right conditions the plants will grow fully emerse erect leaves. Under a bright light the plants can grow fast, and be used to help cycle an aquarium.^[9]

This plant is often used as a vegetable, particularly in Asia.^[10]

References

^ PPG I (2016), "A community-derived classification for extant lycophytes and ferns", Journal of Systematics and Evolution, 54 (6): 563–603, doi:10.1111/jse.12229, S2CID 39980610
^ http://www.anbg.gov.au/fern/aquatic/parkeriaceae.html Archived 2007-11-05 at the Wayback Machine Ceratopteris in Australian National Herbarium
^ Masuyama, Shigeo; Yasuyuki Watano (2010). "Cryptic Species in the Fern Ceratopteris thalictroides (L.) Brongn. (Parkeriaceae). IV. Taxonomic Revision". Acta Phytotax. Geobot. 61 (2): 75–86.
^ Nitta, Joel H.; Schuettpelz, Eric; Ramírez-Barahona, Santiago; Iwasaki, Wataru; et al. (2022). "An Open and Continuously Updated Fern Tree of Life". Frontiers in Plant Science. 13: 909768. doi:10.3389/fpls.2022.909768. PMC 9449725. PMID 36092417.
^ "Tree viewer: interactive visualization of FTOL". FTOL v1.5.0 [GenBank release 256]. 2023. Retrieved 17 August 2023.
^ Chen, X.; Chen, Z.; Huang, W.; Fu, H.; Wang, Q.; Wang, Y.; Cao, J. (2019). "Proteomic analysis of gametophytic sex expression in the fern Ceratopteris thalictroides". PLOS ONE. 14 (8): e0221470. Bibcode:2019PLoSO..1421470C. doi:10.1371/journal.pone.0221470. PMC 6699692. PMID 31425560.
^ Banks, J. A. (1994). "Sex-determining genes in the homosporous fern Ceratopteris". Development. 120 (7): 1949–1958. doi:10.1242/dev.120.7.1949. PMID 7925000.
^ The Complete Guide to Edible Wild Plants. United States Department of the Army. New York: Skyhorse Publishing. 2009. p. 109. ISBN 978-1-60239-692-0. OCLC 277203364.{{cite book}}: CS1 maint: others (link)
^ "How to Plant & Grow Water Sprite (Ceratopteris thalictroides)". May 2021.
^ "Ceratopteris thalictroides - Useful Tropical Plants".