Maidenhair Ferns of the genus Adiantum are global in distribution,
though most species are restricted to the tropics and subtropics.About 225
species (roughly 10% of the total number of described species in the genus) are
found in temperate regions, though most of these are found only in Asia. Nine
species of Adiantum are currently
recognised from Canada and the United States, though four of these are
essentially tropical species with the northernmost limit of their range in the
southern US, one species is global in distribution and found on all continents
except Antarctica, one is found in Asia as well as North America and one is
thought to be introduced. However recent genetic studies of Maidenhair Fern populations
suggest that many of these ‘species’ may in fact be clusters of cryptic
morphospecies (plants which appear identical but which are genetically isolated
from one-another), suggesting that the group may be larger and more complex
than is currently understood.
In a paper published in the
journal PhytoKeys on 21 July 2015, Layne Huiet of the Department of Biology at
Duke University, Martin Lenz and Julie Nelson of the USDA Forest Service at
Shasta-Trinity National Forest, Kathleen Pryer, also of the Department of
Biology at Duke University and Alan Smith of the University Herbarium at the
University of California, Berkeley, describe a new species of Maidenhair Fern
from Shasta County in California.
The new species is named Adiantum shastense, where ‘shastense’ means ‘from Shasta’, the
species having only been found to date around Lake Shasta in Shasta County,
California, an area with a high number on endemic species (species not found
elsewhere). It is essentially similar to Adiantum
jordanii, a species wide-ranging in North America, being a rhizomatous Fern
(Fern which can regrow each year from a creeping underground root) producing up
to 10 fronds 30-60 cm in length. However it has a longer growing season than Adiantum jordanii, persisting later in
the summer.
Fronds of Adiantum shastense growing
in the wild. Huiet et al. (2015).
Adiantum shastense was first identified from herbarium specimens,
some of which were collected over a hundred years ago, during a study into the
globally distributed Adiantum
capillus-veneris, in California; Adiantum
shastense grows alongside Adiantum
capillus-veneris in places, whereas Adiantum
jordanii is generally intolerant of other Maidenhair species. DNA
sequencing analysis of these herbarium specimens revealed that they were
neither Adiantum capillus-veneris nor
Adiantum jordanii, but a new and
previously undescribed species apparently endemic to Shasta County. Subsequent
investigations found it to be widespread within this area, growing on a variety
of substrates, and in places forming the dominant understory plant. Since the
species is currently known only from a limited area, Huiet et al. recommend that it be treated as having a California Rare Plant Rank of 4.3, though they note that unlike other endemic plants of the
Shasta Lake area (but like other Maidenhair Ferns) Adiantum shastense is distributed via wind-blown spores, making it
highly possible that it is also found at (as yet undiscovered) locations
outside of this area.
See also…
Governor Laffan's Fern declared Extinct in the Wild.The International Union for the Conservation of Nature published its annual update of its Red List of Threatened Species on Thursday 12 June 2014, marking the 50th year of the list's existence...
Three new species of Fern from the Middle Triassic of northern Italy.Middle Triassic plant fossils have been collected from the Dolomites for at least a century and a half. These Triassic floras were dominated by Conifers, and were long thought to have lived in an arid...
Follow Sciency Thoughts on
Facebook.
