''Adiantum alarconianum'' is a South American

maidenhair fern ''Adiantum'' (), the maidenhair fern, is a genus of about 250 species of ferns in the subfamily Vittarioideae of the family Pteridaceae, though some researchers place it in its own family, Adiantaceae. The genus name comes from Greek, meaning "un ...

. First scientifically collected in the early 1800s in

Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...

, it is found in neighboring parts of

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

as well. Its

iridescent Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfl ...

stem scales help to differentiate it from other related ferns.

Description

The leaves range from 30 to 50 cm in length, and vary from generally linear to egg-shaped, coming to a point at the tip. The leaf blade is cut into pinnae; the lower and basal pinnae are sometimes cut again into

pinnule A leaflet (occasionally called foliole) in botany is a leaf-like part of a compound leaf. Though it resembles an entire leaf, a leaflet is not borne on a main plant stem or branch, as a leaf is, but rather on a petiole or a branch of the leaf. Co ...

s in the specimens wider at the base. The stalk of the leaf, below the blade (the stipe) may have a few short soft

hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and f ...

s and/or scales on the upper side, or be completely hairless. The stem passing through the leaf blade (the

rachis In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...

) always has such hairs and/or scales on the upper side, but these do not usually extend to the rest of the rachis. When they occur, the hairs often branch into a star-like shape. The stem scales are iridescent, a distinctive feature of the species. The pinnae, which are alternate on the rachis, range in shape from oblong-falcate (somewhat sickle-shaped) to long-triangular. They are asymmetrical at the base, being attached directly (without petioles) to the rachis near one corner of the pinna. The upper surfaces of the pinnae are hairless; the false indusia occur along one edge. They are folded over the upper side of the leaf and are not divided.

Taxonomy

''Adiantum alarconianum'' was originally described as ''A. incisum'' by Carl Presl in publishing the collection of

Thaddäus Haenke Thaddeus Xaverius Peregrinus Haenke (5 October 1761 – 4 November 1816) ( cs, Tadeáš Haenke; es, Tadeo Haenke) was a botanist who participated in the Malaspina Expedition, exploring a significant portion of the Pacific basin including the c ...

in 1825. However, the name ''A. incisum'' had already been used in 1775 to describe a fern collected by

Peter Forsskål Peter Forsskål, sometimes spelled Pehr Forsskål, Peter Forskaol, Petrus Forskål or Pehr Forsskåhl (11 January 1732 – 11 July 1763) was a Swedish-speaking Finnish explorer, orientalist, naturalist, and an apostle of Carl Linnaeus. Earl ...

. Presl's ferns were later held to be synonymous with ''A. alarconianum'', the

type specimen In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...

for which was collected in 1836 and published in 1846 by Charles Gaudichaud.

Distribution and habitat

''Adiantum incisum'' Presl was described as occurring in

Guayas Province Guayas () is a coastal Provinces of Ecuador, province in Ecuador. It is bordered to the west by Manabí Province, Manabí, Santa Elena Province, Ecuador, Santa Elena, and the Pacific Ocean (as the Gulf of Guayaquil); to the east by Los Ríos Pr ...

, near

Guayaquil , motto = Por Guayaquil Independiente en, For Independent Guayaquil , image_map = , map_caption = , pushpin_map = Ecuador#South America , pushpin_re ...

, and in

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, but the latter reference is now held to be an error. The type specimen of ''A. alarconianum'' was also collected near Guayaquil. It has been collected in a number of locations in western

and in the

Galápagos Islands The Galápagos Islands (Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuador ...

, and in the nearby

Tumbes Province Tumbes is a province in Peru, located in the region of the same name. It borders the Pacific Ocean on the north, the Zarumilla Province on the east, the Piura Region and Ecuador on the south and the Contralmirante Villar Province on the west. It ...

of Peru. Peruvian specimens were collected in woods.

References

Bibliography

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External links

Type specimen
of ''A. alarconianum''. {{Taxonbar, from=Q4682646 alarconianum Ferns of Ecuador Flora of Peru Ferns of the Americas Plants described in 1846 Taxa named by Carl Borivoj Presl