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Adiantum trapeziforme
L.
Diamond Maidenhair Fern
Pteridaceae
Adiantum trapeziforme is a species of fern in the family Pteridaceae. It is native to Mexico, Central America, and the Caribbean, and is commonly cultivated and naturalized elsewhere. It should not be confused with the species Adiantum cunninghamii, which has an illegitimate synonym, Adiantum trapeziforme described by Georg Forster (Brownsey and Perrie 2020).
Description
Adiantum trapeziforme is a medium to large fern with thick rhizomes 8 to 15 mm in diameter; rhizomes are covered in lanceolate, brown, entire scales that are about 7 mm long. Leaves are glabrous, relatively large, 40 to 100 cm long, with a stipe that makes up at least half the length of the leaf. The stipe is round in cross section but grooved below, black or dark purple, and shiny. The leaf blade itself is 30 to 40 cm long and wide, roughly triangular to pentagonal in outline, 2-3- or even 4-pinnate. There are 2 to 5 pairs of pinnae that are 10 to 18 cm long, linear in outline, and these are itself divided into pinnules that are 2 to 5 cm long and 1.5 and 2 cm wide, asymmetrically rhomboid to ovate, with a squarish base and margins that are often toothed or irregularly incised. Pinnules are attached via a petiolule 2 to 9 mm long, with the petiole color stopping abruptly at the base of the leaf segment and not “bleeding” into the blade. Fertile segments differ from sterile segments in that part of the apical leaf surface is folded under, forming a false indusium, carrying the sori. Fertile segments typically have 12 to 20 false indusia, which are round and with entire margins (Davidse et al. 1995).
A similar species, called Adiantum pentadactylon, is sometimes considered part of this species. While this species has pinnately compound leaves, articulate (jointed) pinnae that are not glaucous below, and the petiole color not bleeding into the leaf segment, A. pentadactylon has pedately compound leaves, non-articulate pinnae that are glaucous below, and the petiole color bleeding into the base of the leaf segment (Prado and Palacios-Rios 1998).
A similar species, called Adiantum pentadactylon, is sometimes considered part of this species. While this species has pinnately compound leaves, articulate (jointed) pinnae that are not glaucous below, and the petiole color not bleeding into the leaf segment, A. pentadactylon has pedately compound leaves, non-articulate pinnae that are glaucous below, and the petiole color bleeding into the base of the leaf segment (Prado and Palacios-Rios 1998).
Uses
Note: Please see the disclaimer regarding any information about medical or edible uses.
Adiantum trapeziforme is commonly cultivated (McCarthy 2012). It is reported to have antibacterial properties (Quattrocchi 2012).
Distribution
Adiantum trapeziforme prefers wooded slopes and ravines, growing among secondary vegetation or disturbed forests, mainly in non-calcareous soils, at altitudes of up to 1000, occasionally 1100 m. It is a Neotropical species, distributed from Mexico and Central America to Cuba, Jamaica, and the Lesser Antilles (Davidse et al. 1995). Reports of this species in southeastern Brazil refer to the similar species Adiantum pentadactylon (Prado and Palacios-Rios 1998). It has escaped cultivation and is naturalized elsewhere, such as southern Florida and Sri Lanka (McCarthy 2012).
Status
References
Brownsey, P. J., and Perrie, L. R. 2020. Taxonomic notes on the New Zealand flora: lectotypes in Pteridaceae. New Zealand Journal of Botany, 58: 245–254.
Davidse, G., Sousa Sánchez, M., and Knapp, S. 1995. Flora Mesoamericana. Vol. 1 (Psilotaceae a Salviniaceae). México: Universidad Nacional Autónoma de México.
McCarthy, M. R. 2012. Molecular Systematics and Morphology of the Adiantum peruvianum Group (Pteridaceae) [dissertation]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1350236402.
Prado, J., and Palacios-Rios, M. 1998. Taxonomy and distribution of Adiantum trapeziforme and A. pentadactylon. American Fern Journal, 88: 145.
Quattrocchi, U. 2012. CRC World Dictionary of Medicinal and Poisonous Plants Common Names, Scientific Names, Eponyms, Synonyms, and Etymology. Boca Raton, FL: CRC Press.
Davidse, G., Sousa Sánchez, M., and Knapp, S. 1995. Flora Mesoamericana. Vol. 1 (Psilotaceae a Salviniaceae). México: Universidad Nacional Autónoma de México.
McCarthy, M. R. 2012. Molecular Systematics and Morphology of the Adiantum peruvianum Group (Pteridaceae) [dissertation]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1350236402.
Prado, J., and Palacios-Rios, M. 1998. Taxonomy and distribution of Adiantum trapeziforme and A. pentadactylon. American Fern Journal, 88: 145.
Quattrocchi, U. 2012. CRC World Dictionary of Medicinal and Poisonous Plants Common Names, Scientific Names, Eponyms, Synonyms, and Etymology. Boca Raton, FL: CRC Press.
Description
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