''Adiantum alarconianum'' is a South American maidenhair fern. First scientifically collected in the early 1800s in

Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...

, it is found in neighboring parts of

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

as well. Its iridescent 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 pinnules in the specimens wider at the base. The stalk of the leaf, below the blade (the stipe) may have a few short soft hairs and/or scales on the upper side, or be completely hairless. The stem passing through the leaf blade (the rachis) 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 in 1825. However, the name ''A. incisum'' had already been used in 1775 to describe a fern collected by Peter Forsskål. Presl's ferns were later held to be synonymous with ''A. alarconianum'', the type specimen 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, near Guayaquil, and in

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

, 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 () are an archipelago of volcanic islands in the Eastern Pacific, located around the equator, west of the mainland of South America. They form the Galápagos Province of the Republic of Ecuador, with a population of sli ...

, and in the nearby Tumbes Province 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