Banksia rosserae
Encyclopedia
Banksia rosserae is a recently described species of Banksia
. Endemic to inland Western Australia
, it is the only Banksia species to occur solely within the arid zone
.
2½ to three metres high, and three to four metres wide. The trunks are from ten to fifteen centimetres in diameter. Unusually for Banksia species, the grey bark is papery and flaky. The leaves are dark green, five to twelve centimetres long and five to twelve millimetres wide, with serrated margins. Flowers are yellow and occur in Banksias distinctive flower spikes; these are approximately spherical, with a diameter of about five centimetres. The "cones" have a hairy appearance due to the retention of old flower parts. They typically contain from twelve to twenty follicles
, most of which do not open until stimulated to do so by fire
.
enthusiast named John Cullen. According to Collins, Cullen had visited Kirkalocka in search of an undescribed Grevillea species mentioned in the writings of Charles Gardner
(now published as G. kirkalocka); in addition to finding the Grevillea, he also found two B. rosserae plants growing on the top of an orange sand dune.
Irrespective of who first discovered it, its presence in the area was reported to Peter Olde and Neil Marriott. In 2001, Olde, Marriott and Keith Alcock visited the area in search of the undescribed Grevillea species. While there, they also searched for the Banksia, and eventually Alcock located two specimens growing on top of a dune. The plants were clearly an undescribed species, so specimens were collected so that a formal description of the species could be published. The following year it was published as Banksia rosserae Olde & Marriott. The name honours Celia Rosser
, an illustrator, whose three-volume monograph The Banksias
has been acclaimed as one of 20th century's great works of botanical illustration
.
In January 2002, Kevin Collins and John Cullen undertook a search for more plants, locating a clump of six plants about 20 kilometres (12 mi) from the original two, and a further 18 plants on crown land
adjacent to Kirkalocka. No flowering specimen was seen during these visits; indeed, no-one knew what the flower looked like until 2006. In March of that year, storms associated with Cyclone Glenda
dumped a year's worth of rain in the area in a single day, and shortly afterwards, flowers began to form. Two months later, a party of botanists and Banksia enthusiasts visited the area, and observed the flowers for the first time.
(Tennis Ball Banksia), and like that species it has condensed, roughly spherical inflorescences, and slender styles. However, unlike B. laevigata it has a lignotuber
, and terminal inflorescences that hang down instead of being held erect. The lignotuber suggests an affinity with B. lullfitzii
, while the pendulous inflorescences suggest a relationship with the Banksia ser. Tetragonae
series.
Olde and Marriott provisionally placed it in subgenus Banksia
because its inflorescences take the form of Banksia's characteristic flower spikes; Banksia sect. Banksia
because of its straight style
s; and Banksia ser. Cyrtostylis
because it has slender flowers. It was placed alongside B. laevigata, but with the proviso that "we have perceived a close relationship between Banksia laevigata and Banksia rosserae which a more informed study may find superficial."
B. rosserae's current placement within Banksia may be summarised as follows:
in inland Western Australia
. There are 27 plants known, all occurring within a radius of about 20 kilometres (12 mi). The area is around 200 kilometres (125 mi) from where other Banksia species are known to occur, representing "a significant extension of range into the arid zone and a significant geographic disjunction for the genus."
Although most of the land around Mount Magnet has the heavy clay soil and Acacia aneura (Mulga) scrub common throughout semi-arid Western Australia, the area on which B. rosserae occurs is unusual in having deep yellow sand and laterite
. It occurs there with mallee
Eucalyptus
species, over open heath of Grevillea
, Hakea
, Leptospermum
, Melaleuca
, Cryptandra
and Triodia
species. Thus the flora is more like that found on the Swan Coastal Plain
than the arid zone in which it occurs.
Very little is known of the ecology of B. rosserae. Its massive lignotuber is clearly an adaptation to desert conditions, providing a store of water during extended periods of drought, and a store of energy from which it can resprout after bushfire. Marriott also considers its papery bark to be an adaptation to desert conditions, although he does not elaborate on how the plant benefits from it.
Flowering apparently occurs only after rain, and hence may be separated by periods of many years. Pollinators have not been recorded for the species, but extensive data from other Banksia species suggests that insects, birds and nectariferous mammals would all play a role. There is clearly no shortage of pollinators, as most "cones" contain plenty of follicles. Although most follicles observed are closed, a few open ones have been found, suggesting that the species is weakly serotinous
: that is, a few follicles open spontaneously or in response to rain, but most remain closed until burnt.
Seedlings would have little change of surviving in a normal dry season; establishment probably requires several consecutive seasons of good rain. The combination of a bushfire followed by several seasons of cyclonic storms probably only occurs every few hundred years, suggesting that opportunities for seedling recruitment are extremely rare. This would explain why the entire population appears to be over two hundred years old.
There is little information on threats to the species. All known plants appear to be in very good health and free of pests; it seems they are not eaten or damaged by the area's kangaroo
s, goat
s and sheep. Bushfire clearly poses no threat; and the area is free from Phytophthora cinnamomi
dieback, a scourge of most other western Banksia species. Any concerns about future land use are abated by the fact that the largest population occurs on crown land
, which is now being considered for a conservation reserve. In fact, the only perceived threat is the rarity of conditions conducive to seedling recruitment: "it may well be that this banksia has become so adapted to its harsh environment that its long-term future in the wild is in doubt."
Because of the absence of any specific threat to the species, it has not been declared rare or threatened. However, Olde and Marriott declared it to merit Priority One listing on the Department of Environment and Conservation's Declared Rare and Priority Flora List. Consequently they withheld the precise location of their specimens "for conservation reasons".
, and as a garden plant in hot dry climates.
Banksia
Banksia is a genus of around 170 species in the plant family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes and fruiting "cones" and heads. When it comes to size, banksias range from prostrate woody shrubs to trees up...
. Endemic to inland Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
, it is the only Banksia species to occur solely within the arid zone
Desert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...
.
Description
B. rosserae grows as a multi-stemmed shrubShrub
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...
2½ to three metres high, and three to four metres wide. The trunks are from ten to fifteen centimetres in diameter. Unusually for Banksia species, the grey bark is papery and flaky. The leaves are dark green, five to twelve centimetres long and five to twelve millimetres wide, with serrated margins. Flowers are yellow and occur in Banksias distinctive flower spikes; these are approximately spherical, with a diameter of about five centimetres. The "cones" have a hairy appearance due to the retention of old flower parts. They typically contain from twelve to twenty follicles
Follicle (fruit)
In botany, a follicle is a dry unilocular many-seeded fruit formed from one carpel and dehiscing by the ventral suture in order to release seeds, such as in larkspur, magnolia, banksia, peony and milkweed....
, most of which do not open until stimulated to do so by fire
Fire
Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....
.
Taxonomic history
Reports of who first discovered B. rosserae are somewhat contradictory. Peter Olde and Neil Marriott acknowledge Ann Pilkington of Kirkalocka, "who discovered Banksia rosserae and who drew it to our attention through various third parties." However, Kevin Collins states that it was first discovered in September 2000 by a GrevilleaGrevillea
Grevillea is a diverse genus of about 360 species of evergreen flowering plants in the protea family Proteaceae, native to Australia, New Guinea, New Caledonia, and Sulawesi. It was named in honour of Charles Francis Greville. The species range from prostrate shrubs less than 0.5 m tall to trees...
enthusiast named John Cullen. According to Collins, Cullen had visited Kirkalocka in search of an undescribed Grevillea species mentioned in the writings of Charles Gardner
Charles Gardner
Charles Austin Gardner was a Western Australian botanist.Born in Lancaster, England on 6 January 1896, he emigrated to Western Australia with his family in 1909....
(now published as G. kirkalocka); in addition to finding the Grevillea, he also found two B. rosserae plants growing on the top of an orange sand dune.
Irrespective of who first discovered it, its presence in the area was reported to Peter Olde and Neil Marriott. In 2001, Olde, Marriott and Keith Alcock visited the area in search of the undescribed Grevillea species. While there, they also searched for the Banksia, and eventually Alcock located two specimens growing on top of a dune. The plants were clearly an undescribed species, so specimens were collected so that a formal description of the species could be published. The following year it was published as Banksia rosserae Olde & Marriott. The name honours Celia Rosser
Celia Rosser
Celia Elizabeth Rosser is a renowned Australian botanical illustrator, best known for having published The Banksias, a three-volume series of monographs containing watercolour paintings of every Banksia species....
, an illustrator, whose three-volume monograph The Banksias
The Banksias
The Banksias, by Celia Rosser, is a three-volume series of monographs containing paintings of every Banksia species. Its publication represented the first time such a large genus had been entirely painted by a single botanical artist. It has been described as "one of the outstanding botanical works...
has been acclaimed as one of 20th century's great works of botanical illustration
Botanical illustration
Botanical illustration is the art of depicting the form, colour, and details of plant species, frequently in watercolour paintings. These are often printed with a botanical description in book, magazines, and other media...
.
In January 2002, Kevin Collins and John Cullen undertook a search for more plants, locating a clump of six plants about 20 kilometres (12 mi) from the original two, and a further 18 plants on crown land
Crown land
In Commonwealth realms, Crown land is an area belonging to the monarch , the equivalent of an entailed estate that passed with the monarchy and could not be alienated from it....
adjacent to Kirkalocka. No flowering specimen was seen during these visits; indeed, no-one knew what the flower looked like until 2006. In March of that year, storms associated with Cyclone Glenda
Cyclone Glenda
Severe Tropical Cyclone Glenda was among the strongest tropical cyclones to make landfall in Western Australia, though it moved ashore in a lightly populated region. It began as a tropical low on 15 March in the Gulf of Carpentaria...
dumped a year's worth of rain in the area in a single day, and shortly afterwards, flowers began to form. Two months later, a party of botanists and Banksia enthusiasts visited the area, and observed the flowers for the first time.
Infrageneric placement
B. rosserae's relationship to other Banksia species is uncertain. Its leaves are virtually indistinguishable from narrow-leaved forms of B. laevigataBanksia laevigata
Banksia laevigata is a species of shrub in the plant genus Banksia. It occurs in Western Australia's semi-arid shrubland from Southern Cross south to the Fitzgerald River National Park. It is composed of two closely related subspecies, B. laevigata subsp. laevigata and B. laevigata...
(Tennis Ball Banksia), and like that species it has condensed, roughly spherical inflorescences, and slender styles. However, unlike B. laevigata it has a lignotuber
Lignotuber
A lignotuber is a starchy swelling of the root crown possessed by some plants as a protection against destruction of the plant stem by fire. The crown contains buds from which new stems may sprout, and a sufficient store of nutrients to support a period of growth in the absence of...
, and terminal inflorescences that hang down instead of being held erect. The lignotuber suggests an affinity with B. lullfitzii
Banksia lullfitzii
Banksia lullfitzii is a species of shrub in the plant genus Banksia. A many-branched, spreading bush with golden-orange flowers, it occurs in scattered populations over a large area of the eastern goldfields of Western Australia...
, while the pendulous inflorescences suggest a relationship with the Banksia ser. Tetragonae
Banksia ser. Tetragonae
Banksia ser. Tetragonae is a taxonomic series in the genus Banksia. It consists of three closely related species of erect shrub with pendulous inflorescences in section Banksia. These are B. lemanniana , B. caleyi and B. aculeata ....
series.
Olde and Marriott provisionally placed it in subgenus Banksia
Banksia subg. Banksia
Banksia subg. Banksia is a valid botanic name for a subgenus of Banksia. As an autonym, it necessarily contains the type species of Banksia, B. serrata . Within this constraint, however, there have been various circumscriptions.-Banksia verae:B. subg...
because its inflorescences take the form of Banksia's characteristic flower spikes; Banksia sect. Banksia
Banksia sect. Banksia
Banksia sect. Banksia is one of four sections of Banksia subgenus Banksia. It contains those species of subgenus Banksia with straight or sometimes curved but not hooked styles. These species all have cylindrical inflorescences and usually exhibit a bottom-up sequence of flower anthesis...
because of its straight style
Gynoecium
Gynoecium is most commonly used as a collective term for all carpels in a flower. A carpel is the ovule and seed producing reproductive organ in flowering plants. Carpels are derived from ovule-bearing leaves which evolved to form a closed structure containing the ovules...
s; and Banksia ser. Cyrtostylis
Banksia ser. Cyrtostylis
Banksia ser. Cyrtostylis is a valid botanic name for a taxonomic series within the plant genus Banksia. First published at sectional rank by George Bentham in 1870, it was demoted to a series by Alex George in 1981. The name has had three circumscriptions.-According to Bentham:Bentham published B....
because it has slender flowers. It was placed alongside B. laevigata, but with the proviso that "we have perceived a close relationship between Banksia laevigata and Banksia rosserae which a more informed study may find superficial."
B. rosserae's current placement within Banksia may be summarised as follows:
- BanksiaBanksiaBanksia is a genus of around 170 species in the plant family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes and fruiting "cones" and heads. When it comes to size, banksias range from prostrate woody shrubs to trees up...
- B. subg. BanksiaBanksia subg. BanksiaBanksia subg. Banksia is a valid botanic name for a subgenus of Banksia. As an autonym, it necessarily contains the type species of Banksia, B. serrata . Within this constraint, however, there have been various circumscriptions.-Banksia verae:B. subg...
- B. sect. BanksiaBanksia sect. BanksiaBanksia sect. Banksia is one of four sections of Banksia subgenus Banksia. It contains those species of subgenus Banksia with straight or sometimes curved but not hooked styles. These species all have cylindrical inflorescences and usually exhibit a bottom-up sequence of flower anthesis...
- B. ser. SalicinaeBanksia ser. SalicinaeBanksia ser. Salicinae is a valid botanic name for a series of Banksia. First published by Carl Meissner in 1856, the name has had three circumscriptions.-According to Meissner:...
(11 species, 7 subspecies) - B. ser. GrandesBanksia ser. GrandesBanksia ser. Grandes is a taxonomic series in the genus Banksia. It consists of two closely related species in section Banksia, both endemic to Western Australia. These are B. grandis and B. solandri ....
(2 species) - B. ser. BanksiaBanksia ser. BanksiaBanksia ser. Banksia is avalid botanic name for a series of Banksia. As an autonym, it necessarily contains the type species of Banksia, B. serrata . Within this constraint, however, there have been various circumscriptions.-According to Bentham:Banksia ser. Banksia originated in 1870 as...
(8 species) - B. ser. CrocinaeBanksia ser. CrocinaeBanksia ser. Crocinae is a taxonomic series in the genus Banksia. It consists of four closely related species, all of which are endemic to Western Australia; namely B. prionotes , B. burdettii , B. hookeriana and B. victoriae...
(4 species) - B. ser. ProstrataeBanksia ser. ProstrataeBanksia ser. Prostratae is a taxonomic series in the genus Banksia. It consists of six closely related species in section Banksia, all endemic to Western Australia, with a prostrate habit.Banksia ser...
(6 species, 3 varieties) - B. ser. CyrtostylisBanksia ser. CyrtostylisBanksia ser. Cyrtostylis is a valid botanic name for a taxonomic series within the plant genus Banksia. First published at sectional rank by George Bentham in 1870, it was demoted to a series by Alex George in 1981. The name has had three circumscriptions.-According to Bentham:Bentham published B....
- B. mediaBanksia mediaThe Southern Plains Banksia , also known as Golden Stalk Banksia, is a species of shrub in the plant genus Banksia. It occurs on the south coast of Western Australia between Albany and Israelite Bay, where it is a common plant....
- B. praemorsaBanksia praemorsaThe Cut-leaf Banksia is a species of shrub or tree in the plant genus Banksia. It occurs in a few isolated populations on the south coast of Western Australia between Albany and Cape Riche. Seeds do not require any treatment, and take 30 to 49 days to germinate.-References:...
- B. epicaBanksia epicaBanksia epica is a shrub that grows on the south coast of Western Australia. A spreading bush with wedge-shaped serrated leaves and large creamy-yellow flower spikes, it grows up to 3½ metres high. It is known only from two isolated populations in the remote south east of the state, near the...
- B. pilostylisBanksia pilostylisThe Marsh Banksia is a species of shrub in the plant genus Banksia. It occurs on the south coast of Western Australia around Esperance. Seeds do not require any treatment, and take 18 to 49 days to germinate.-External links:...
- B. attenuataBanksia attenuataBanksia attenuata, commonly known as the candlestick banksia or slender banksia, is a species of plant in the proteaceae family. Commonly a tree, it reaches 10 m high, but is often a shrub in dryer areas 0.4 to 2 m high...
- B. ashbyiBanksia ashbyiThe Ashby's Banksia is a species of shrub in the plant genus Banksia. It occurs in heath and spinifex country along the coast of Western Australia between Geraldton and Exmouth.-Description:...
- B. benthamianaBanksia benthamianaBentham's Banksia is a species of shrub or tree in the plant genus Banksia. It occurs in scattered populations in the Wheatbelt region of Western Australia, one near Mullewa and the other near Dalwallinu.-Description:...
- B. audaxBanksia audaxBanksia audax is a species of shrub in the plant genus Banksia. It occurs over a large area in the central south of Western Australia.-Description:...
- B. lullfitziiBanksia lullfitziiBanksia lullfitzii is a species of shrub in the plant genus Banksia. A many-branched, spreading bush with golden-orange flowers, it occurs in scattered populations over a large area of the eastern goldfields of Western Australia...
- B. rosserae
- B. elderianaBanksia elderianaThe Swordfish Banksia , commonly known as the swordfish banksia or palm banksia, is a species of shrub in the plant genus Banksia. It occurs in two disjunct areas in the Goldfields-Esperance region of Western Australia...
- B. laevigataBanksia laevigataBanksia laevigata is a species of shrub in the plant genus Banksia. It occurs in Western Australia's semi-arid shrubland from Southern Cross south to the Fitzgerald River National Park. It is composed of two closely related subspecies, B. laevigata subsp. laevigata and B. laevigata...
(2 subspecies) - B. elegansBanksia elegansThe Elegant Banksia is a species of shrub or small tree in the plant genus Banksia. It occurs only over a 65 square kilometre area north and west of Eneabba, Western Australia.-Ecology:...
- B. lindleyanaBanksia lindleyanaBanksia lindleyana, commonly known as the Porcupine Banksia, is a species of woody shrub in the genus Banksia of the family Proteaceae. It generally grows as a small shrub to 1 m high with long narrow serrated leaves, and bright yellow oval or round inflorescences...
- B. media
- B. ser. TetragonaeBanksia ser. TetragonaeBanksia ser. Tetragonae is a taxonomic series in the genus Banksia. It consists of three closely related species of erect shrub with pendulous inflorescences in section Banksia. These are B. lemanniana , B. caleyi and B. aculeata ....
(3 species) - B. ser. Bauerinae (1 species)
- B. ser. QuercinaeBanksia ser. QuercinaeBanksia ser. Quercinae is avalid botanic name for a series of Banksia. First published by Carl Meissner in 1856, the name has had three circumscriptions.-According to Meissner:...
(2 species)
- B. ser. Salicinae
- B. sect. Coccinea (1 species)
- B. sect. OncostylisBanksia sect. OncostylisBanksia sect. Oncostylis is one of four sections of subgenus Banksia subg. Banksia. It contains those Banksia species with hooked pistils. All of the species in Oncostylis also exhibit a top-down sequence of flower anthesis, except for Banksia nutans which is bottom-up.Banksia sect...
(4 series, 22 species, 4 subspecies, 11 varieties)
- B. sect. Banksia
- B. subg. IsostylisBanksia subg. IsostylisBanksia subg. Isostylis is a subgenus of Banksia. It contains three closely related species, all of which occur only in Southwest Western Australia. Members of subgenus Isostylis have dome-shaped flower heads that are superficially similar to those of B. ser...
(3 species)
- B. subg. Banksia
Distribution
Banksia rosserae is known only from an area south-south-east of Mount MagnetMount Magnet, Western Australia
Mount Magnet is an old Western Australian gold rush town. The name was chosen during exploration of the region due to an isolated hill 5 km north west of the town current townsite. This hill has an extremely high iron content and affected the compasses of explorers...
in inland Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
. There are 27 plants known, all occurring within a radius of about 20 kilometres (12 mi). The area is around 200 kilometres (125 mi) from where other Banksia species are known to occur, representing "a significant extension of range into the arid zone and a significant geographic disjunction for the genus."
Although most of the land around Mount Magnet has the heavy clay soil and Acacia aneura (Mulga) scrub common throughout semi-arid Western Australia, the area on which B. rosserae occurs is unusual in having deep yellow sand and laterite
Laterite
Laterites are soil types rich in iron and aluminium, formed in hot and wet tropical areas. Nearly all laterites are rusty-red because of iron oxides. They develop by intensive and long-lasting weathering of the underlying parent rock...
. It occurs there with mallee
Mallee (habit)
Mallee is the growth habit of certain eucalypt species that grow with multiple stems springing from an underground lignotuber, usually to a height of no more than ten metres...
Eucalyptus
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
species, over open heath of Grevillea
Grevillea
Grevillea is a diverse genus of about 360 species of evergreen flowering plants in the protea family Proteaceae, native to Australia, New Guinea, New Caledonia, and Sulawesi. It was named in honour of Charles Francis Greville. The species range from prostrate shrubs less than 0.5 m tall to trees...
, Hakea
Hakea
Hakea is a genus of 149 species of shrubs and small trees in the Proteaceae, native to Australia. They are found throughout the country, with the highest species diversity being found in the south west of Western Australia....
, Leptospermum
Leptospermum
Leptospermum is a genus of about 80-86 species of plants in the myrtle family Myrtaceae. Most species are endemic to Australia, with the greatest diversity in the south of the continent; but one species extends to New Zealand, another to Malaysia, and L. recurvum is endemic to Malaysia.They...
, Melaleuca
Melaleuca
Melaleuca is a genus of plants in the myrtle family Myrtaceae known for its natural soothing and cleansing properties. There are well over 200 recognised species, most of which are endemic to Australia...
, Cryptandra
Cryptandra
Cryptandra is a genus of shrub in the plant family Rhamnaceae.-List of species:* C. alpina* C. amara** C. a var. amara** C. a var...
and Triodia
Triodia (plant genus)
Triodia is a large genus of hummock-forming grass endemic to Australia; they are commonly known as spinifex, although they are not a part of the coastal genus Spinifex. There are currently 64 recognised species...
species. Thus the flora is more like that found on the Swan Coastal Plain
Swan Coastal Plain
The Swan Coastal Plain in Western Australia is the geographic feature which contains the Swan River as it travels west to the Indian Ocean. The coastal plain continues well beyond the boundaries of the Swan River and its tributaries, as a geological and biological zone, one of Western Australia's...
than the arid zone in which it occurs.
Ecology
Flowering apparently occurs only after rain, and hence may be separated by periods of many years. Pollinators have not been recorded for the species, but extensive data from other Banksia species suggests that insects, birds and nectariferous mammals would all play a role. There is clearly no shortage of pollinators, as most "cones" contain plenty of follicles. Although most follicles observed are closed, a few open ones have been found, suggesting that the species is weakly serotinous
Serotiny
Serotiny is an ecological adaptation exhibited by some seed plants, in which seed release occurs in response to an environmental trigger, rather than spontaneously at seed maturation. The most common and best studied trigger is fire, and the term serotiny is often used to refer to this specific case...
: that is, a few follicles open spontaneously or in response to rain, but most remain closed until burnt.
Seedlings would have little change of surviving in a normal dry season; establishment probably requires several consecutive seasons of good rain. The combination of a bushfire followed by several seasons of cyclonic storms probably only occurs every few hundred years, suggesting that opportunities for seedling recruitment are extremely rare. This would explain why the entire population appears to be over two hundred years old.
There is little information on threats to the species. All known plants appear to be in very good health and free of pests; it seems they are not eaten or damaged by the area's kangaroo
Kangaroo
A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...
s, goat
Goat
The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s and sheep. Bushfire clearly poses no threat; and the area is free from Phytophthora cinnamomi
Phytophthora cinnamomi
Phytophthora cinnamomi is a soil-borne water mould that produces an infection which causes a condition in plants called root rot or dieback. The plant pathogen is one of the world's most invasive species and is present in over 70 countries from around the world.- Life cycle and effects on plants :P...
dieback, a scourge of most other western Banksia species. Any concerns about future land use are abated by the fact that the largest population occurs on crown land
Crown land
In Commonwealth realms, Crown land is an area belonging to the monarch , the equivalent of an entailed estate that passed with the monarchy and could not be alienated from it....
, which is now being considered for a conservation reserve. In fact, the only perceived threat is the rarity of conditions conducive to seedling recruitment: "it may well be that this banksia has become so adapted to its harsh environment that its long-term future in the wild is in doubt."
Because of the absence of any specific threat to the species, it has not been declared rare or threatened. However, Olde and Marriott declared it to merit Priority One listing on the Department of Environment and Conservation's Declared Rare and Priority Flora List. Consequently they withheld the precise location of their specimens "for conservation reasons".
Cultivation
Banksia rosserae is poorly known in cultivation as yet. In 2003, Kevin Collins reported that "early trials have proven good seed viability and rapid young seedling development". The following year Neil Marriott reported that "seedlings germinate well with smoked water during spring, and young plants establishing here in deep granite sands and sandy loams at Stawell are growing slowly but steadily." It was his view that the species was likely to be of value to the cut flower industryFloriculture
Floriculture, or flower farming, is a discipline of horticulture concerned with the cultivation of flowering and ornamental plants for gardens and for floristry, comprising the floral industry...
, and as a garden plant in hot dry climates.