Orobanche minor
Encyclopedia
Orobanche minor, or Common Broomrape, is a holoparasitic angiosperm
belonging to the genus Orobanche
; a genus of about 150 non-photosynthetic
plants that parasitize
other autotrophic
plants.
.
Common Broomrape grows in a wide variety of soils, namely moist, light (sandy), medium (loamy) and heavy (clay) soils that are acid, neutral or basic. It can grow in semi-shade or in full sunlight.
The species appears in a wide range of colours from red-brown, yellow-brown to purple. Yellow specimens are also not uncommon and its this extreme variability that makes identification on the basis of size or colour uncertain.
Common Broomrape is parasitic on various members of the Pea (Fabaceae) and Daisy (Asteraceae) families. Although widespread, its appearance is sporadic; despite this it can occur in vast colonies from time to time. The main flowering season is from May until the end of August. The species has efficient seed dispersal and is largely inbreeding so that populations preferentially parasitizing a particular species which has its own clear ecological preferences and may become effectively isolated and eventually may produce distinct taxa.
The plants are attached to their host by means of haustoria, which transfer nutrients from the host to the parasite. Only the hemiparasitic species possess an additional extensive root system. The root system is reduced as its function is mainly anchorage of the plant.
, but has been widely introduced elsewhere, for example in the United States
. In the United Kingdom it is widely recorded in southern England, less common in Wales, rarely recorded in lowland Scotland and absent from the Highlands and outer islands.
: O. minor var. minor, O. minor var. flava, O. minor var. compositarum and O. minor subsp. maritima. Chromosome No.: 2n = 38. The genetic structure of populations of O. minor are under investigation using molecular markers and DNA sequencing to help resolve the taxonomic and nomenclatural problems that have historically been linked with this species.
to the Poaceae
(=Gramineae) but with a clear preference for the Fabaceae
(=Leguminosae) and Asteraceae
(=Compositae). However races occurring on different species of host are genetically divergent and physiologically adapted to their local hosts, and may therefore be in a state of incipient speciation
. Urgent conservation efforts are required as the survival of some intraspecific taxa is very uncertain.
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
belonging to the genus Orobanche
Broomrape
Broomrape or Broom-rape is a genus of over 200 species of parasitic herbaceous plants in the family Orobanchaceae, mostly native to the temperate Northern Hemisphere. Some species formerly included in this genus are now referred to the genus Conopholis.The broomrape plant is small, from...
; a genus of about 150 non-photosynthetic
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
plants that parasitize
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
other autotrophic
Autotroph
An autotroph, or producer, is an organism that produces complex organic compounds from simple inorganic molecules using energy from light or inorganic chemical reactions . They are the producers in a food chain, such as plants on land or algae in water...
plants.
Characteristics and growth requirements
O. minor grows to 0.5 m (1ft 8in) and is a perrenial. The flowers are hermaphroditeHermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
.
Common Broomrape grows in a wide variety of soils, namely moist, light (sandy), medium (loamy) and heavy (clay) soils that are acid, neutral or basic. It can grow in semi-shade or in full sunlight.
The species appears in a wide range of colours from red-brown, yellow-brown to purple. Yellow specimens are also not uncommon and its this extreme variability that makes identification on the basis of size or colour uncertain.
Common Broomrape is parasitic on various members of the Pea (Fabaceae) and Daisy (Asteraceae) families. Although widespread, its appearance is sporadic; despite this it can occur in vast colonies from time to time. The main flowering season is from May until the end of August. The species has efficient seed dispersal and is largely inbreeding so that populations preferentially parasitizing a particular species which has its own clear ecological preferences and may become effectively isolated and eventually may produce distinct taxa.
The plants are attached to their host by means of haustoria, which transfer nutrients from the host to the parasite. Only the hemiparasitic species possess an additional extensive root system. The root system is reduced as its function is mainly anchorage of the plant.
Distribution
Common broomrape is one of the most widespread species, and is native to Southern EuropeSouthern Europe
The term Southern Europe, at its most general definition, is used to mean "all countries in the south of Europe". However, the concept, at different times, has had different meanings, providing additional political, linguistic and cultural context to the definition in addition to the typical...
, but has been widely introduced elsewhere, for example in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. In the United Kingdom it is widely recorded in southern England, less common in Wales, rarely recorded in lowland Scotland and absent from the Highlands and outer islands.
Taxonomy
Phylogenetic analyses have placed this species in the taxonomically difficult Minores species complex. Four infraspecific taxa of Common broomrape are currently recognised in the United KingdomUnited Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
: O. minor var. minor, O. minor var. flava, O. minor var. compositarum and O. minor subsp. maritima. Chromosome No.: 2n = 38. The genetic structure of populations of O. minor are under investigation using molecular markers and DNA sequencing to help resolve the taxonomic and nomenclatural problems that have historically been linked with this species.
Hosts and speciation
The Common Broomrape is highly generalist in its host range, and can infect hundreds of species in families from the RanunculaceaeRanunculaceae
Ranunculaceae are a family of about 1700 species of flowering plants in about 60 genera, distributed worldwide....
to the Poaceae
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...
(=Gramineae) but with a clear preference for the Fabaceae
Fabaceae
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...
(=Leguminosae) and Asteraceae
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
(=Compositae). However races occurring on different species of host are genetically divergent and physiologically adapted to their local hosts, and may therefore be in a state of incipient speciation
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...
. Urgent conservation efforts are required as the survival of some intraspecific taxa is very uncertain.