Gymnocarpium robertianum
Encyclopedia
Gymnocarpium robertianum (limestone oak fern or scented oak fern) is a fern of the family Woodsiaceae
.
, two to three pinnate
fronds. Fronds arise from creeping rhizomes and have long, delicate rachis
. The sori are borne in round clumps on the underside of the blade and lack an indusium. This species differs from the closely related G. dryopteris in having a densely glandular rachis
as well as a more sparsely glandular underside to the blade.
G . robertianum is thought to hybridise with G . appalachianum giving rise to Gymnocarpium × heterosporum W. H. Wagner. This hybrid was only known from Pennsylvania where it has now been eradicated. The hybrid between G. robertianum and G. dryopteris is Gymnocarpium × achriosporum Sarvela this taxon is known from Sweden and Quebec.
.
This species is protected in Illinois and Michigan and is protected under the Flora Protection Order in Ireland.
This species is a calcicole
and as such is restricted to alkaline rich areas. In the British Isles and Ireland its preferential habitat is grykes in limestone pavement
. In Michigan the species is most frequent in Thuja occidentalis
swamps.
Woodsiaceae
Woodsiaceae or Cliff Fern is a family of fern within the Aspleniales order....
.
Description
Gymnocarpium robertianum has small (10-50cm), deltateLeaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
, two to three pinnate
Pinnate
Pinnate is a term used to describe feather-like or multi-divided features arising from both sides of a common axis in plant or animal structures, and comes from the Latin word pinna meaning "feather", "wing", or "fin". A similar term is pectinate, which refers to a comb-like arrangement of parts...
fronds. Fronds arise from creeping rhizomes and have long, delicate rachis
Rachis
Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...
. The sori are borne in round clumps on the underside of the blade and lack an indusium. This species differs from the closely related G. dryopteris in having a densely glandular rachis
Rachis
Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...
as well as a more sparsely glandular underside to the blade.
G . robertianum is thought to hybridise with G . appalachianum giving rise to Gymnocarpium × heterosporum W. H. Wagner. This hybrid was only known from Pennsylvania where it has now been eradicated. The hybrid between G. robertianum and G. dryopteris is Gymnocarpium × achriosporum Sarvela this taxon is known from Sweden and Quebec.
Distribution
G. robertianum is a circumboreal species with populations in Europe, North America and the Caucasus MountainsCaucasus Mountains
The Caucasus Mountains is a mountain system in Eurasia between the Black Sea and the Caspian Sea in the Caucasus region .The Caucasus Mountains includes:* the Greater Caucasus Mountain Range and* the Lesser Caucasus Mountains....
.
This species is protected in Illinois and Michigan and is protected under the Flora Protection Order in Ireland.
This species is a calcicole
Calcicole
A calcicole or calciphyte is a plant that does not tolerate acidic soil. The word is derived from the Latin 'to dwell on chalk'. Under acidic conditions, aluminium becomes more soluble and phosphate-less. As a consequence, calcicoles grown on acidic soils often develop the symptoms of aluminium...
and as such is restricted to alkaline rich areas. In the British Isles and Ireland its preferential habitat is grykes in limestone pavement
Limestone pavement
A limestone pavement is a natural karst landform consisting of a flat, incised surface of exposed limestone that resembles an artificial pavement. The term is mainly used in the UK where many of these landforms have developed distinctive surface patterning resembling block of paving...
. In Michigan the species is most frequent in Thuja occidentalis
Thuja occidentalis
Thuja occidentalis is an evergreen coniferous tree, in the cypress family Cupressaceae, which is widely cultivated for use as an ornamental plant known as American Arbor Vitae. The endemic occurrence of this species is a northeastern distribution in North America...
swamps.
External links
- Gymnocarpium robertianum at Flora of North America http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200003907
- Gymnocarpium robertianum at PLANTS Profile http://plants.usda.gov/java/profile?symbol=GYRO
- Distribution of Gymnocarpium robertianum in the British Isles at BSBI maps http://www.bsbimaps.org.uk/atlas/map_page.php?spid=2054.0&sppname=Gymnocarpium%20robertianum&commname=Limestone%20Fern
- Gymnocarpium robertianum at Hardy Fern Library http://hardyfernlibrary.com/ferns/listspecies.cfm?auto=72