Bromus interruptus
Encyclopedia
Bromus interruptus, commonly known as the interrupted brome, is a plant
in the true grass family
.
It is endemic to southern and central England
, but is believed to have been extinct in the wild since 1972. After several decades in cultivation, the interrupted brome was re-introduced to a reserve in Aston Rowant
in 2004, marking the first known re-introduction of an extinct plant in Britain. The plant was a weed
of waste places and arable agriculture, particularly of sainfoin (Onobrychis viciifolia
) cultivation. It can be distinguished from all other Bromus species by its deeply split, or bifid, palea
.
The plant appeared to spread rapidly after its discovery in 1849, which is normally indicative of introduced species
. However, the species is thought to have arisen in the 19th century as a new species through a substantial and abrupt genetic change. It is thought to have gone into decline with the replacement of horses by motor vehicles from the late 19th century onwards, reducing the demand for sainfoin as fodder
, and additionally by improved seed cleaning methods.
. The green leaves measure 6 to 20 cm long by 2 to 6 mm wide and are long-linear in shape with a pointed apex. They are covered in a soft pubescence. The leaf sheaths are tubular with the lower portion having a soft pubescence replaced by shorter hairs in the upper portion. The ligule
s measure 1 to 2 mm and are membranous and toothed.
The inflorescence
is a dense, oblong panicle
that measures 2 to 9 cm in length and up to 20 mm thick. It is erect, greyish green in colour and, as the name suggests, usually interrupted, sometimes even reduced to a single spikelet. Its branches measure up to 15 mm in length. The sessile (i.e. without a stalk) or nearly sessile spikelets occur in dense clusters with each measuring 10 to 15 mm long by 5 to 8 mm broad. They are covered in soft pubescence and are plump with a broadly ovate (i.e. egg-shaped) to broadly oblong shape. Each contains 5 to 11 flowers and they slowly break up beneath each lemma
once mature.
The glumes, or sterile husks at the base of each spikelet, are unequal in morphology and persist after maturity. Both the upper and lower glumes may have apices ranging from blunt to abruptly pointed. The lower glume is 5 to 7 mm long with 3 to 7 veins and an oblong to elliptical outline. The upper one is slightly larger, measuring 6 to 9 mm long with 5 to 9 veins and an ovate to broadly elliptical shape.
The lemma
s, the outer of the two husks enclosing a flower, measure 7.5 to 9 mm long by 5 to 5.5 mm wide and have an obovate to obovate-elliptic outline. They have 7 to 9 prominent veins, 2 very small teeth, and membranous margins that are more flexible than the otherwise firm centre. Each lemma has a fine, rough awn that measures 4 to 8 mm and may be either be straight or bending. The palea
s, the upper of the two husks that enclose a flower, are narrowly elliptical in outline and are shorter than the lemmas. They are bifid (i.e. split in two) to the base with the split keel being somewhat pubescent. The bifid paleas distinguish the interrupted brome from all other species in the genus. Each spikelet contains 5 to 8 flowers. The anthers are 1 to 1.5 mm long. The caryopsis
is tightly enclosed and is narrowly ellipsoid in outline. The chromosome
number is 2n=28.
south to eastern Kent
and northern Somerset
. It was last seen in the wild in Cambridgeshire
in 1972 and is currently classified as extinct in the wild. Its demise is thought to have been due to improved seed cleaning methods, which effectively eradicated the species as a weed of crops. Since that time the plant has persisted in cultivation in the United Kingdom. It has also been introduced to the Netherlands, where it is now established.
The plant was found primarily in waste places and as a weed in arable crops, particularly sainfoin (Onobrychis viciifolia
), rye grass (Lolium perenne
) and clover (Trifolium sp.). It was also found on the sides of roads and tracks.
, collected seeds in the 1970s from the last population of the interrupted brome in Cambridge. He germinated the seeds and grew the plants in a pot on his window sill. In 1979 at a Botanical Society of the British Isles conference he presented seeds to several of his colleagues. Through him the plants began to be cultivated at the Royal Botanic Gardens at Kew and Edinburgh.
Stewart Henchie, a botanist from Kew Gardens, began a project to re-introduce the interrupted brome into the wild. Under his leadership, Kew Gardens and Paignton Zoo
grew large quantities of the plants to procure seeds for an eventual re-introduction. In the summer of 2004, these seeds were dispersed at English Nature
's reserve at Aston Rowant
in the Chilterns. The plants successfully germinated, fruited and persisted. This marked the first extinct plant to be re-introduced into the wild in British history.
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
in the true grass family
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...
.
It is endemic to southern and central England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, but is believed to have been extinct in the wild since 1972. After several decades in cultivation, the interrupted brome was re-introduced to a reserve in Aston Rowant
Aston Rowant
Aston Rowant is a village and civil parish about south of Thame in South Oxfordshire, England. The parish includes the villages of Aston Rowant and Kingston Blount, and adjoins Buckinghamshire to the southeast....
in 2004, marking the first known re-introduction of an extinct plant in Britain. The plant was a weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
of waste places and arable agriculture, particularly of sainfoin (Onobrychis viciifolia
Onobrychis viciifolia
Onobrychis viciifolia is a species of legume known by the common name sainfoin; other species in genus Onobrychis may be known by this name as well. Other common names for this species include esparcet and pipirigallo. This is a perennial herb which is native to Eurasia, but it is widely cultivated...
) cultivation. It can be distinguished from all other Bromus species by its deeply split, or bifid, palea
Palea (botany)
Palea, in botany, refers to one of the bract-like organs of the grass spikelet . It is the uppermost of the two chaff-like bracts that enclose the grass floret . It is often cleft at the tip, implying that it may be a double structure derived from the union of two separate organs...
.
The plant appeared to spread rapidly after its discovery in 1849, which is normally indicative of introduced species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
. However, the species is thought to have arisen in the 19th century as a new species through a substantial and abrupt genetic change. It is thought to have gone into decline with the replacement of horses by motor vehicles from the late 19th century onwards, reducing the demand for sainfoin as fodder
Fodder
Fodder or animal feed is any agricultural foodstuff used specifically to feed domesticated livestock such as cattle, goats, sheep, horses, chickens and pigs. Most animal feed is from plants but some is of animal origin...
, and additionally by improved seed cleaning methods.
Description
Bromus interruptus is an annual or biennial herb. Its slender to somewhat stout culms measure 20 to 100 cm and occur as either loosely tufted or solitary. They are erect, very lightly pubescent, unbranched and contain 2 to 4 nodesPlant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
. The green leaves measure 6 to 20 cm long by 2 to 6 mm wide and are long-linear in shape with a pointed apex. They are covered in a soft pubescence. The leaf sheaths are tubular with the lower portion having a soft pubescence replaced by shorter hairs in the upper portion. 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....
s measure 1 to 2 mm and are membranous and toothed.
The inflorescence
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 a dense, oblong panicle
Panicle
A panicle is a compound raceme, a loose, much-branched indeterminate inflorescence with pedicellate flowers attached along the secondary branches; in other words, a branched cluster of flowers in which the branches are racemes....
that measures 2 to 9 cm in length and up to 20 mm thick. It is erect, greyish green in colour and, as the name suggests, usually interrupted, sometimes even reduced to a single spikelet. Its branches measure up to 15 mm in length. The sessile (i.e. without a stalk) or nearly sessile spikelets occur in dense clusters with each measuring 10 to 15 mm long by 5 to 8 mm broad. They are covered in soft pubescence and are plump with a broadly ovate (i.e. egg-shaped) to broadly oblong shape. Each contains 5 to 11 flowers and they slowly break up beneath each 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...
once mature.
The glumes, or sterile husks at the base of each spikelet, are unequal in morphology and persist after maturity. Both the upper and lower glumes may have apices ranging from blunt to abruptly pointed. The lower glume is 5 to 7 mm long with 3 to 7 veins and an oblong to elliptical outline. The upper one is slightly larger, measuring 6 to 9 mm long with 5 to 9 veins and an ovate to broadly elliptical shape.
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...
s, the outer of the two husks enclosing a flower, measure 7.5 to 9 mm long by 5 to 5.5 mm wide and have an obovate to obovate-elliptic outline. They have 7 to 9 prominent veins, 2 very small teeth, and membranous margins that are more flexible than the otherwise firm centre. Each lemma has a fine, rough awn that measures 4 to 8 mm and may be either be straight or bending. The palea
Palea (botany)
Palea, in botany, refers to one of the bract-like organs of the grass spikelet . It is the uppermost of the two chaff-like bracts that enclose the grass floret . It is often cleft at the tip, implying that it may be a double structure derived from the union of two separate organs...
s, the upper of the two husks that enclose a flower, are narrowly elliptical in outline and are shorter than the lemmas. They are bifid (i.e. split in two) to the base with the split keel being somewhat pubescent. The bifid paleas distinguish the interrupted brome from all other species in the genus. Each spikelet contains 5 to 8 flowers. The anthers are 1 to 1.5 mm long. The caryopsis
Caryopsis
In botany, a caryopsis is a type of simple dry fruit — one that is monocarpelate and indehiscent and resembles an achene, except that in a caryopsis the pericarp is fused with the thin seed coat....
is tightly enclosed and is narrowly ellipsoid in outline. The chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
number is 2n=28.
Distribution and habitat
The interrupted brome is endemic to south-central and southeastern England and was formerly found from southern LincolnshireLincolnshire
Lincolnshire is a county in the east of England. It borders Norfolk to the south east, Cambridgeshire to the south, Rutland to the south west, Leicestershire and Nottinghamshire to the west, South Yorkshire to the north west, and the East Riding of Yorkshire to the north. It also borders...
south to eastern Kent
Kent
Kent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of...
and northern Somerset
Somerset
The ceremonial and non-metropolitan county of Somerset in South West England borders Bristol and Gloucestershire to the north, Wiltshire to the east, Dorset to the south-east, and Devon to the south-west. It is partly bounded to the north and west by the Bristol Channel and the estuary of the...
. It was last seen in the wild in Cambridgeshire
Cambridgeshire
Cambridgeshire is a county in England, bordering Lincolnshire to the north, Norfolk to the northeast, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the west...
in 1972 and is currently classified as extinct in the wild. Its demise is thought to have been due to improved seed cleaning methods, which effectively eradicated the species as a weed of crops. Since that time the plant has persisted in cultivation in the United Kingdom. It has also been introduced to the Netherlands, where it is now established.
The plant was found primarily in waste places and as a weed in arable crops, particularly sainfoin (Onobrychis viciifolia
Onobrychis viciifolia
Onobrychis viciifolia is a species of legume known by the common name sainfoin; other species in genus Onobrychis may be known by this name as well. Other common names for this species include esparcet and pipirigallo. This is a perennial herb which is native to Eurasia, but it is widely cultivated...
), rye grass (Lolium perenne
Lolium perenne
Lolium perenne, common name Perennial Ryegrass, is a grass from the family Poaceae. It is native to Europe, Asia and northern Africa, but is widely cultivated and naturalised around the world.-Description:...
) and clover (Trifolium sp.). It was also found on the sides of roads and tracks.
Re-introduction
The late Philip M. Smith (1941-2004), a botanist specialising in brome grasses from the University of EdinburghUniversity of Edinburgh
The University of Edinburgh, founded in 1583, is a public research university located in Edinburgh, the capital of Scotland, and a UNESCO World Heritage Site. The university is deeply embedded in the fabric of the city, with many of the buildings in the historic Old Town belonging to the university...
, collected seeds in the 1970s from the last population of the interrupted brome in Cambridge. He germinated the seeds and grew the plants in a pot on his window sill. In 1979 at a Botanical Society of the British Isles conference he presented seeds to several of his colleagues. Through him the plants began to be cultivated at the Royal Botanic Gardens at Kew and Edinburgh.
Stewart Henchie, a botanist from Kew Gardens, began a project to re-introduce the interrupted brome into the wild. Under his leadership, Kew Gardens and Paignton Zoo
Paignton Zoo
Paignton Zoo Environmental Park, is a zoo in Paignton, Devon, England. The zoo is part of South West Environmental Parks Ltd which is owned by the Whitley Wildlife Conservation Trust . It is a combined zoo and botanic garden that welcomes over half a million visitors a year. WWCT also runs Living...
grew large quantities of the plants to procure seeds for an eventual re-introduction. In the summer of 2004, these seeds were dispersed at English Nature
English Nature
English Nature was the United Kingdom government agency that promoted the conservation of wildlife, geology and wild places throughout England between 1990 and 2006...
's reserve at Aston Rowant
Aston Rowant
Aston Rowant is a village and civil parish about south of Thame in South Oxfordshire, England. The parish includes the villages of Aston Rowant and Kingston Blount, and adjoins Buckinghamshire to the southeast....
in the Chilterns. The plants successfully germinated, fruited and persisted. This marked the first extinct plant to be re-introduced into the wild in British history.