Chrysanthemoides monilifera
Encyclopedia
Chrysanthemoides monilifera (also known as Boneseed or Bitou Bush in Australasia, or Bietou, Tick Berry, Bosluisbessie, or Weskusbietou in South Africa)
is an evergreen flowering shrub
with glossy round leaves in the Asteraceae
(daisy) family. It is native to South Africa
, such as the Cape Flats Dune Strandveld
habitat
.
The plant has become a major environmental weed and invasive species
in Australia and New Zealand.
, the other is Chrysanthemoides incana.
C. monilifera has six recognized subspecies:
In Australia
, C. m. ssp. monilifera is known by the common name 'Boneseed', while C. m. ssp. rotundata is known by the common name 'Bitou Bush'. In New Zealand
subspecies are not distinguished and C. monilifera is simply known as 'Boneseed'.
C. monilifera was first described by Carolus Linnaeus
in 1754 under the name Osteospermum monilifera, however it was given its current binomial name in 1943 by T. Norlindh.
The species name monilifera comes from the Latin
, monile, meaning necklace or collar, referring to the shiny fruit arranged around the flowers like a necklace.
s in swirls of 5-8 'petals' (ray florets) up to 30 mm (1.4 in) in diameter. Fruit are berry-like, spherical at around 8 mm in diameter, and turn dark-brown to black with a bone-coloured seed inside of 6–7 mm diameter. Leaves are 2–6 cm (0.8-2.4 in) long by 1.5–5 cm (0.6–2 in) wide, oval tapering to the base with irregularly toothed margins.
Bitou Bush can be distinguished from Boneseed in part due to its more rounded sprawling habit to 1.5–2 m (4.5–7 ft), less noticeably toothy leaf margins and seeds that are egg-like rather than spherical.
Both Boneseed and Bitou Bush hybridise readily, however, so examples of plants demonstrating a fusion of traits is possible.
, reaching into southern Namibia
and Mozambique
. The most widespread subspecies in South Africa is pisifera. Subspecies rotundata is concentrated along the eastern coast of South Africa from its southern tip through to the Mozambique border. Subspecies monilifera is concentrated around Cape Town
and the Cape Peninsula
on South Africa's south western coast.
and New South Wales
, while subspecies monilifera (Boneseed) has naturalised along and near the coast in parts of Victoria
and South Australia
.
, is common in coastal locations throughout the North Island
, and can also be found in the South Island
in Nelson City, Port Hills
(Christchurch
) and the Otago Peninsula
.
for 10 years or more, and this reserve in turn enables the species to quickly recolonize a burnt area.
An individual plant can produce 50,000 seeds a year, about 60% of which are viable. Once germinated, seedlings grow vigorously with dense, bushy growth. This lush growth shades out and displaces slower growing native species that might otherwise occupy the same ecological niche. Rapid, vigorous growth also means that C. monilifera is capable of flowering and setting seed within 12–18 months, making it extremely persistent even in situations where disturbance or regular management activity is common.
Once established, the plant's shallow root system enables it to absorb moisture after light rain before the moisture reaches the roots of more deeply rooted species further limiting opportunities for slower growing species to establish and out-compete C. monilifera over time. Furthermore, outside of Southern Africa the plant has few local, indigenous pathogens or predators to control its growth also reducing the potential for gaps to emerge that might provide opportunities for other species to reestablish. The net consequence of C. moniliferas growth characteristics is that outside of its natural ecosystem it can ultimately form large, dense, unhealthy stands of a single species with extraordinarily poor biodiversity.
The plant can extend its existing range in a variety of ways. Its fruit is attractive to birds, rabbits, other animals and even some insects such as ants, and because seeds are tough and difficult to digest they will often be dispersed in animal droppings
. Seeds can also spread on vehicles and equipment, in contaminated soil, in garden waste, along water drainage lines and deliberately by human intervention.
C. monilifera, unlike many other weed species, is not generally considered to be a problem for agricultural productivity due to its sensitivity to trampling as well as being readily grazed by stock.
Another method of control available is the use of controlled burns, however there are risks associated with this method. Principally, C. monilifera has higher moisture levels than many Australian indigenous species and therefore in Australia a higher than normal intensity fire is required for burns to be effective. This can in turn have detrimental impacts on indigenous vegetation evolved in response to more frequent, lower intensity fire. Furthermore, fire can trigger regermination from the extensive C. monilifera seed bank, potentially worsening the situation unless a program is implemented to monitor and control C. monilifera seedlings following the burn. If C. monilifera seedlings are removed, however, this can be extremely effective at exhausting the seed bank and minimising the chances of reinfestation.
Various methods of biological control have been attempted, particularly the introduction of insects adapted as natural enemies of C. monilifera such as the Bitou Tip Moth (Comostolopsis germana) and Bitou Seed Fly (Mesoclanis polana). In Australia, while these have had some success in controlling Bitou Bush (ssp. rotundata), to date they have not had similar success in combating Boneseed (ssp. monilifera).
is an evergreen flowering shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
with glossy round leaves in the 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...
(daisy) family. It is native to South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, such as the Cape Flats Dune Strandveld
Cape Flats Dune Strandveld
Cape Flats Dune Strandveld is an endangered vegetation type. This is a unique type of Cape Strandveld that is endemic to the coastal areas in Cape Town, including the Cape Flats district. -Habitat:Strandveld means “beach scrub” in the Afrikaans language...
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...
.
The plant has become a major environmental weed and 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....
in Australia and New Zealand.
Taxonomy
Chrysanthemoides monilifera is one of only two members of the genus ChrysanthemoidesChrysanthemoides
Chrysanthemoides is one of eight genera of the Calenduleae, with a center of diversity in South Africa. The genera contains only two species, but is known for the invasive "Bitou Bush" Chrysanthemoides monilifera. Studies of this genus have determined that there is a large amount of genetic...
, the other is Chrysanthemoides incana.
C. monilifera has six recognized subspecies:
- ssp. canescens
- ssp. monilifera
- ssp. pisifera
- ssp. rotundata
- ssp. septentrionalis
- ssp. subcanescens
In Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, C. m. ssp. monilifera is known by the common name 'Boneseed', while C. m. ssp. rotundata is known by the common name 'Bitou Bush'. In New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
subspecies are not distinguished and C. monilifera is simply known as 'Boneseed'.
C. monilifera was first described by Carolus Linnaeus
Carolus Linnaeus
Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...
in 1754 under the name Osteospermum monilifera, however it was given its current binomial name in 1943 by T. Norlindh.
The species name monilifera comes from the 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...
, monile, meaning necklace or collar, referring to the shiny fruit arranged around the flowers like a necklace.
Description
Boneseed is a perennial, woody, upright shrub, growing to 3 m (10 ft), although occasionally taller. It is a member of the Asteraceae (daisy) family and has showy, bright yellow flowerFlower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s in swirls of 5-8 'petals' (ray florets) up to 30 mm (1.4 in) in diameter. Fruit are berry-like, spherical at around 8 mm in diameter, and turn dark-brown to black with a bone-coloured seed inside of 6–7 mm diameter. Leaves are 2–6 cm (0.8-2.4 in) long by 1.5–5 cm (0.6–2 in) wide, oval tapering to the base with irregularly toothed margins.
Bitou Bush can be distinguished from Boneseed in part due to its more rounded sprawling habit to 1.5–2 m (4.5–7 ft), less noticeably toothy leaf margins and seeds that are egg-like rather than spherical.
Both Boneseed and Bitou Bush hybridise readily, however, so examples of plants demonstrating a fusion of traits is possible.
Distribution and habitat
Chrysanthemoides monilifera occurs naturally in coastal areas of South AfricaSouth Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, reaching into southern Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
and Mozambique
Mozambique
Mozambique, officially the Republic of Mozambique , is a country in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west and Swaziland and South Africa to the southwest...
. The most widespread subspecies in South Africa is pisifera. Subspecies rotundata is concentrated along the eastern coast of South Africa from its southern tip through to the Mozambique border. Subspecies monilifera is concentrated around Cape Town
Cape Town
Cape Town is the second-most populous city in South Africa, and the provincial capital and primate city of the Western Cape. As the seat of the National Parliament, it is also the legislative capital of the country. It forms part of the City of Cape Town metropolitan municipality...
and the Cape Peninsula
Cape Peninsula
The Cape Peninsula is a generally rocky peninsula that juts out for 75 km into the Atlantic Ocean at the south-western extremity of the African continent. At the southern end of the peninsula are Cape Point and the Cape of Good Hope...
on South Africa's south western coast.
Australia
In Australia, subspecies rotundata (Bitou Bush) has naturalised along the coast of QueenslandQueensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
and New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, while subspecies monilifera (Boneseed) has naturalised along and near the coast in parts of Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
and South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
.
New Zealand
In New Zealand C. monilifera, which is listed on the National Pest Plant AccordNational Pest Plant Accord
The National Pest Plant Accord identifies pest plants that are prohibited from sale and commercial propagation and distribution across New Zealand....
, is common in coastal locations throughout the North Island
North Island
The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...
, and can also be found in the South Island
South Island
The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...
in Nelson City, Port Hills
Port Hills
The Port Hills form the northern rim of the ancient Lyttelton volcano, separating the port of Lyttelton from the city of Christchurch in Canterbury, New Zealand...
(Christchurch
Christchurch
Christchurch is the largest city in the South Island of New Zealand, and the country's second-largest urban area after Auckland. It lies one third of the way down the South Island's east coast, just north of Banks Peninsula which itself, since 2006, lies within the formal limits of...
) and the Otago Peninsula
Otago Peninsula
The Otago Peninsula is a long, hilly indented finger of land that forms the easternmost part of Dunedin, New Zealand. Volcanic in origin, it forms one wall of the eroded valley that now forms Otago Harbour. The peninsula lies south-east of Otago Harbour and runs parallel to the mainland for...
.
Impact
In Australia, C. monilifera has been particularly successful in invading natural bushland. In part, this is due to the species' ability to establish on relatively nutrient-poor soils and in areas exposed to salt such as coastlines, as well as the ability of the seeds to germinate readily. Disturbances such as fire can assist C. monilifera to spread as the plant produces a large amount of seed that can persist in the soil seed bankSoil Seed Bank
The soil seed bank refers to the natural storage of seeds, often dormant, within the soil of most ecosystems. The study of soil seed banks started in 1859 when Charles Darwin observed the emergence of seedlings using soil samples from the bottom of a lake. The first scientific paper on the subject...
for 10 years or more, and this reserve in turn enables the species to quickly recolonize a burnt area.
An individual plant can produce 50,000 seeds a year, about 60% of which are viable. Once germinated, seedlings grow vigorously with dense, bushy growth. This lush growth shades out and displaces slower growing native species that might otherwise occupy the same ecological niche. Rapid, vigorous growth also means that C. monilifera is capable of flowering and setting seed within 12–18 months, making it extremely persistent even in situations where disturbance or regular management activity is common.
Once established, the plant's shallow root system enables it to absorb moisture after light rain before the moisture reaches the roots of more deeply rooted species further limiting opportunities for slower growing species to establish and out-compete C. monilifera over time. Furthermore, outside of Southern Africa the plant has few local, indigenous pathogens or predators to control its growth also reducing the potential for gaps to emerge that might provide opportunities for other species to reestablish. The net consequence of C. moniliferas growth characteristics is that outside of its natural ecosystem it can ultimately form large, dense, unhealthy stands of a single species with extraordinarily poor biodiversity.
The plant can extend its existing range in a variety of ways. Its fruit is attractive to birds, rabbits, other animals and even some insects such as ants, and because seeds are tough and difficult to digest they will often be dispersed in animal droppings
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
. Seeds can also spread on vehicles and equipment, in contaminated soil, in garden waste, along water drainage lines and deliberately by human intervention.
C. monilifera, unlike many other weed species, is not generally considered to be a problem for agricultural productivity due to its sensitivity to trampling as well as being readily grazed by stock.
Control
C. monilifera is potentially susceptible to a range of control strategies, however Burgman and Lindenmayer recommended that the strategy chosen be responsive to the local situation and available resources. Due to its relatively shallow root system removal by hand is an ideal method of control. Where manual removal is impractical many common herbicides can be used, in which case the herbicide is commonly applied directly to the wood of the plant via a cut notch or at the end of a pruned stump. Mechanical removal of C. monilifera by tractor or other machinery can also be effective, however this can be extremely indiscriminate and is only recommended in areas of poor environmental values and minimal erosion risk.Another method of control available is the use of controlled burns, however there are risks associated with this method. Principally, C. monilifera has higher moisture levels than many Australian indigenous species and therefore in Australia a higher than normal intensity fire is required for burns to be effective. This can in turn have detrimental impacts on indigenous vegetation evolved in response to more frequent, lower intensity fire. Furthermore, fire can trigger regermination from the extensive C. monilifera seed bank, potentially worsening the situation unless a program is implemented to monitor and control C. monilifera seedlings following the burn. If C. monilifera seedlings are removed, however, this can be extremely effective at exhausting the seed bank and minimising the chances of reinfestation.
Various methods of biological control have been attempted, particularly the introduction of insects adapted as natural enemies of C. monilifera such as the Bitou Tip Moth (Comostolopsis germana) and Bitou Seed Fly (Mesoclanis polana). In Australia, while these have had some success in controlling Bitou Bush (ssp. rotundata), to date they have not had similar success in combating Boneseed (ssp. monilifera).