Bromus interruptus

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Interrupted brome
Bromus interruptus and sainfoin.jpg
Bromus interruptus flowering spike with sainfoin flowering in the background
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Poales
Family: Poaceae
Subfamily: Pooideae
Genus: Bromus
Species:
B. interruptus
Binomial name
Bromus interruptus
Synonyms

Bromus mollis var. interruptusHack.

Bromus interruptus, commonly known as the interrupted brome, [2] is a flowering plant in the grass family. It is endemic to southern and central England, which became extinct in the wild in 1972. After several decades in cultivation, the interrupted brome was re-introduced to Aston Rowant National Nature Reserve 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.

Contents

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. [3]

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 nodes. 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 ligules measure 1 to 2 mm and are membranous and toothed. [4]

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. [4]

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. [4]

Bromus interruptus flowers, separated from a seed head or spikelet, each showing a ripe seed (caryopsis) and a deeply split palea Bromus interruptus flowers.jpg
Bromus interruptus flowers, separated from a seed head or spikelet, each showing a ripe seed (caryopsis) and a deeply split palea

The lemmas, 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 straight or bending. The paleas, 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. [4] The bifid paleas distinguish the interrupted brome from all other species in the genus. [5] 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. [4]

Distribution and habitat

The interrupted brome is endemic to south–central and south-eastern England and was formerly found from southern Lincolnshire 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. [3]

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.). [3] It was also found on the sides of roads and tracks. [4]

Re-introduction

Philip M. Smith (1941–2004), a botanist from the University of Edinburgh who specialised in brome grasses, 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. [6]

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 2003, seeds were sown in the wild on a farm in Whittlesford in Cambridgeshire under the protection of A. R. Arbon MBE. This was the first introduction into the wild under the supervision of Stewart Henchie the plants persisted until 2006 longer than the subsequent introduction at Aston Rowant. In the summer of 2004, more seeds were dispersed at English Nature's Aston Rowant National Nature Reserve 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. [6]

Related Research Articles

<i>Onobrychis</i> Genus of flowering plants in the bean family Fabaceae

Onobrychis, the sainfoins, are a genus of Eurasian perennial herbaceous plants of the legume family (Fabaceae). Including doubtfully distinct species and provisionally accepted taxa, about 150 species are presently known. The Flora Europaea lists 23 species of Onobrychis; the main centre of diversity extends from Central Asia to Iran, with 56 species – 27 of which are endemic – in the latter country alone. O. viciifolia is naturalized throughout many countries in Europe and North America grasslands on calcareous soils.

<i>Bromus arvensis</i> Species of grass

Bromus arvensis, the field brome, is a brome grass native to Europe and Asia. The specific epithet arvensis is Latin, meaning "of cultivated land".

<i>Bromus hordeaceus</i> Species of grass

Bromus hordeaceus, the soft brome, is an annual or biennial species of grass in the true grass family (Poaceae). It is also known in North America as bull grass, soft cheat, and soft chess.

<i>Bromus secalinus</i> Species of grass

Bromus secalinus is a species of bromegrass known as rye brome. The specific epithet secalinus is Latin, meaning "rye-like". The fruits are hard, rounded glumes that appear superficially similar to the rye grain, which gives the brome its common and scientific name. The grass has a diploid number of 28.

<i>Bromus madritensis</i> Species of grass

Bromus madritensis is a species of brome grass known by the common name compact brome. The specific epithet madritensis refers to Madrid, Spain. It has a diploid number of 28.

<i>Bromus briziformis</i> Species of grass

Bromus briziformis is a species of brome grass known by the common name rattlesnake brome. The specific epithet briziformis comes from the resemblance of the grass to grasses of the genus Briza, particularly Briza maxima. The common name is derived from the resemblance of the spikelets to the rattles of rattlesnakes. The grass has a diploid number of 14.

<i>Bromus catharticus</i> Species of grass

Bromus catharticus is a species of brome grass known by the common names rescuegrass, grazing brome, prairie grass, and Schrader's bromegrass. The specific epithet catharticus is Latin, meaning cathartic. The common name rescuegrass refers to the ability of the grass to provide forage after harsh droughts or severe winters. The grass has a diploid number of 42.

<i>Bromus ciliatus</i> Species of grass

Bromus ciliatus is a species of brome grass known by the common name fringed brome. It is native to most of North America, including most of Canada, most of the United States except for some portions of the South, and northern Mexico. It is a plant of many habitats, including temperate coniferous forest. The specific epithet ciliatus is Latin for "ciliate", referring to the delicate hairs of the leaf blades.

<i>Bromus kalmii</i> Species of grass

Bromus kalmii, the Arctic brome or prairie brome, is a species of brome grass. It is a native bunchgrass in the North-central and Northeastern United States, the Great Lakes region, and eastern Canada. The specific epithet kalmii refers to its discoverer Pehr Kalm.

<i>Melica ciliata</i> Species of plant

Melica ciliata, the hairy melic or silky spike melic, is a species of flowering plant in the grass family Poaceae, native to Europe, north Africa and temperate Asia. It has been introduced to South Australia.

<i>Bromus erectus</i> Species of grass

Bromus erectus, commonly known as erect brome, upright brome or meadow brome, is a dense, course, tufted perennial grass. It can grow to 120 centimetres (47 in). Like many brome grasses the plant is hairy. The specific epithet erectus is Latin, meaning "erect". The diploid number of the grass is 56.

<i>Bromus marginatus</i> Species of flowering plant

Bromus marginatus is a species of grass known by the common name mountain brome. It is native to western North America, and it is used widely for grazing animals and revegetating landscapes.

<i>Bromus latiglumis</i> Species of grass

Bromus latiglumis, the earlyleaf brome, is a grass native to North America. The specific epithet latiglumis is Latin for "broad-glumed", referring to the wide glumes.

<i>Bromus nottowayanus</i> Species of grass

Bromus nottowayanus, the Nottoway Valley brome or satin brome, is a brome grass native to North America. The specific epithet nottowayanus refers to the Nottoway Valley. The grass has a diploid number of 14.

<i>Bromus japonicus</i> Species of grass

Bromus japonicus, the Japanese brome, is an annual brome grass native to Eurasia. The grass has a diploid number of 14.

<i>Bromus squarrosus</i> Species of grass

Bromus squarrosus, the rough brome, is a brome grass native to Russia and Europe. The specific epithet squarrosus is Latin, meaning "with spreading tips". The grass has a diploid number of 14.

<i>Bromus rigidus</i> Species of grass

Bromus rigidus, the ripgut brome, is a grass native to Eurasia and naturalized in North America. The specific epithet rigidus means rigid or stiff.

Bromus pacificus, the Pacific brome, is a perennial grass native to the Pacific coast of North America. Bromus pacificus has a diploid number of 28.

<i>Bromus racemosus</i> Species of grass in the genus Bromus

Bromus racemosus, the smooth brome or bald brome, is a species of flowering plant in the family Poaceae. It is native to subarctic and temperate Eurasia, and widely introduced elsewhere, including North America, Iceland, the Southern Cone of South America, the Korean Peninsula, Australia, and New Zealand. It grows in alkaline meadows and in waste places.

<i>Bromus texensis</i> Species of grass

Bromus texensis, the Texas brome, is an annual grass native to Texas.

References

  1. ↑ "IUCN Red List of Threatened Species: Bromus interruptus". IUCN Red List of Threatened Species. 10 January 2011.
  2. ↑ BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
  3. 1 2 3 UK Biodiversity Group Tranche 2 Action Plans, vol. 1: Vertebrates and vascular plants, 1998, p. 133, archived from the original on 2008-03-07, retrieved 2008-03-18
  4. 1 2 3 4 5 6 Sell, Peter; Murrell, Gina (1996), Flora of Great Britain and Ireland, vol. 5, p. 205, ISBN   0-521-55339-3
  5. ↑ Hubbard, C. E. (1984), "Interrupted brome, Bromus interruptus (Hack.) Druce", Grasses: a Guide to their Structure, Identification, Uses and Distribution in the British Isles (3rd ed.), Penguin Books, pp. 80–81, ISBN   978-0-14-013227-4
  6. 1 2 Randall, David (24 July 2005), "Back from the dead: scientist revives lost plant of old England", The Independent on Sunday, archived from the original on 18 December 2013
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