Yorkshire Fog
Encyclopedia
Yorkshire Fog or Velvet Grass, Holcus lanatus, is a perennial grass in the Poaceae
Family. 'Lanatus' is latin
for 'wooly' which describes the plant's hairy texture.
In parts of northern Europe the grass is a common native grass species and a hardy pasture grass. Yorkshire Fog, Tufted Grass, or Meadow Soft Grass are the common names used. In North America, where it is an invasive species
, the names are Velvet Grass or Common Velvet Grass.
Yorkshire fog or Velvet Grass has velvety grey-green leaves. The shoots are round. The base of the shoots are white with pink stripes or veins - these are used in identification and are known by certain ecologists as 'stripey pyjamas'. The inflorescence
is robust and often tinged purple. It produces a large amount of seed and is a rapid coloniser of disturbed ground. It prefers wetter ground, often seen around drainage ditches. The ligule
is 1 to 4mm long, blunt and hairy.
Holcus lanatus can also be told apart from H. mollis by its beardless node
s on the culm
; the absence of rhizomes; the awn
of the upper lemma
becoming hooked when dry and not projecting beyond the tips of the glumes.
It spreads vegetatively by developing new shoots and roots at its nodes. Plants form a blanket of runners on the soil surface. Semi-prostrate rosettes of shoots called 'mops' may form at the end of the runners. These mops root readily in contact with moist soil.
A male sterile hybrid with Holcus mollis exists with 2n = 21 chromosomes. Hybrids tend to resemble H. lanatus in their morphology.
In a European survey of weed seed contamination in cereal seed in 1970, Yorkshire fog (Holcus lanatus) was found in 1% of samples. All of this was home saved seed. Yorkshire fog is an indicator of poor soil, too low stocking or poor drainage. It is tolerant of ranges of soil pH, but grows best between pH 5.0 and 7.5; exhibits climatic tolerance over a wide altitude range; severe frosts kill Yorkshire fog under certain conditions; and it does not survive trampling and puddling. It can be controlled in some European locations by increasing available potassium
and phosphorus
, increasing stocking rate and improved drainage. This is not effective in North America.
) and survives droughts and hot summers as seed. It is distasteful to stock unless young and not much else is available. The flowers are wind pollinated and out-crossing predominates. The seeds start to become viable 5 to 9 days after flowering and are completely viable after 20 days. Seeds are shed from June to early autumn. Seed numbers per panicle range from 100 to 380. The average seed number per plant ranges from 177,000 to 240,000 depending on time of emergence.
in native grasslands and disrupts other ecosystem also. In Yosemite National Park
it is one of nine priority noxious weeds
to control for habitat restoration and regenerating native plant balances. Holcus lanatus forms a dense stand that can exclude other plants and may reduce or eliminate native Poacea species and other Genrera diversity.
butterflies
. It is rarely utilized by the Essex Skipper
. In its native range it may occur in plant associations such as the Juncus subnodulosus-Cirsium palustre fen-meadow
habitat
.
Poaceae
The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...
Family. 'Lanatus' is latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for 'wooly' which describes the plant's hairy texture.
In parts of northern Europe the grass is a common native grass species and a hardy pasture grass. Yorkshire Fog, Tufted Grass, or Meadow Soft Grass are the common names used. In North America, where it is an invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
, the names are Velvet Grass or Common Velvet Grass.
Characteristics and hybrids
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
is robust and often tinged purple. It produces a large amount of seed and is a rapid coloniser of disturbed ground. It prefers wetter ground, often seen around drainage ditches. The ligule
Ligule
A ligule — is a thin outgrowth at the junction of leaf and leafstalk of many grasses and sedges or a strap-shaped corolla, such as that of a ray floret in plants in the daisy family....
is 1 to 4mm long, blunt and hairy.
Holcus lanatus can also be told apart from H. mollis by its beardless node
Node
In general, a node is a localised swelling or a point of intersection .Node may refer to:In mathematics:*Node , behaviour for an ordinary differential equation near a critical point...
s on the culm
Culm
Culm, in botanical context, originally referred to a stem of any type of plant. It is derived from the Latin word for 'stalk' and now specifically refers to the above-ground or aerial stems of grasses and sedges....
; the absence of rhizomes; the awn
Awn
In botany, an awn is either a hair- or bristle-like appendage on a larger structure, or in the case of the Asteraceae, a stiff needle-like element of the pappus....
of the upper lemma
Lemma (botany)
Lemma is a phytomorphological term used in botany referring to a part of the spikelet of grasses . It is the lowermost of two chaff-like bracts enclosing the grass floret. It often bears a long bristle called an awn, and may be similar in form to the glumes - chaffy bracts at the base of each...
becoming hooked when dry and not projecting beyond the tips of the glumes.
It spreads vegetatively by developing new shoots and roots at its nodes. Plants form a blanket of runners on the soil surface. Semi-prostrate rosettes of shoots called 'mops' may form at the end of the runners. These mops root readily in contact with moist soil.
A male sterile hybrid with Holcus mollis exists with 2n = 21 chromosomes. Hybrids tend to resemble H. lanatus in their morphology.
Invasive species and habitat preferences
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
and phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
, increasing stocking rate and improved drainage. This is not effective in North America.
Noxious weed
Yorkshire fog or Velvet Grass is a significant pest weed in Australia, as it is a winter growing grass (C3 carbon fixationC3 carbon fixation
carbon fixation is a metabolic pathway for carbon fixation in photosynthesis. This process converts carbon dioxide and ribulose bisphosphate into 3-phosphoglycerate through the following reaction:...
) and survives droughts and hot summers as seed. It is distasteful to stock unless young and not much else is available. The flowers are wind pollinated and out-crossing predominates. The seeds start to become viable 5 to 9 days after flowering and are completely viable after 20 days. Seeds are shed from June to early autumn. Seed numbers per panicle range from 100 to 380. The average seed number per plant ranges from 177,000 to 240,000 depending on time of emergence.
Invasive species
In North America Velvet Grass (Holcus lanatus) is an invasive speciesInvasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
in native grasslands and disrupts other ecosystem also. In Yosemite National Park
Yosemite National Park
Yosemite National Park is a United States National Park spanning eastern portions of Tuolumne, Mariposa and Madera counties in east central California, United States. The park covers an area of and reaches across the western slopes of the Sierra Nevada mountain chain...
it is one of nine priority noxious weeds
Noxious weeds
A noxious weed is an invasive species of a plant that has been designated by country, state or provincial, or national agricultural authorities as one that is injurious to agricultural and/or horticultural crops, natural habitats and/or ecosystems, and/or humans or livestock...
to control for habitat restoration and regenerating native plant balances. Holcus lanatus forms a dense stand that can exclude other plants and may reduce or eliminate native Poacea species and other Genrera diversity.
Insect foodplant status
Holcus lanatus in its natural habitat is a food source for the Speckled Wood, Wall and especially Small SkipperSmall Skipper
The Small Skipper Thymelicus sylvestris butterfly of the Hesperiidae family.-Appearance, behaviour and distribution:It has a rusty orange colour to the wings, upper body and the tips of the antennae. The body is silvery white below and it has a wingspan of 25–30 mm. This butterfly is very...
butterflies
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...
. It is rarely utilized by the Essex Skipper
Essex Skipper
The Essex Skipper is a butterfly of the Hesperiidae family. In North America, it is known as the European Skipper....
. In its native range it may occur in plant associations such as the Juncus subnodulosus-Cirsium palustre fen-meadow
Juncus subnodulosus-Cirsium palustre fen-meadow
The Juncus subnodulosus-Cirsium palustre fen-meadow is a plant association characteristically found on damp ground in portions of western Europe...
habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
.
See also
- Holcus mollis
- Invasive grasses of North AmericaInvasive grasses of North AmericaGrasses are one of the most abundant floras on all continents except Antarctica. Their divergence is estimated to have taken place 200 million years ago. Humans have intentionally and unintentionally introduced these species to North America through travel and trade. On the North American plains,...
- Invasive plant species
- Poaceae
- Native grasses of California