Banksia ilicifolia
Encyclopedia
Banksia ilicifolia, commonly known as Holly-leaved Banksia, is a tree
in the plant Proteaceae
family
. Endemic to southwest
Western Australia
, it belongs to Banksia subg. Isostylis
, a subgenus of three closely related Banksia
species with inflorescence
s that are dome-shaped heads rather than characteristic Banksia flower spikes. It is generally encountered as a tree up to 10 m (35 ft) high, with prickly green foliage and yellow and red-tinged flowers. Both the scientific and common names arises from the similarity of its foliage to that of the English holly Ilex.
Although Banksia ilicifolia is variable in habit, with low coastal shrubby forms on the south coast near Albany, there are no recognised varieties as such. Unlike its close relatives, Banksia ilicifolia regenerates after bushfire by regrowing from epicormic buds under its bark. It is rarely cultivated.
It has a stout trunk up to 50 cm (20 in) in diameter, and thick, fibrous, grey bark. Resembling those of holly, its leaves are a dark shiny green colour, and variously obovate, elliptic, truncate or undulate in shape, and 3–10 cm (1–4 in) long. The leaf edges are generally serrated and quite prickly. The leaves sit atop petioles 0.3–1 cm in length. The upper and undersurface of the leaves are initially covered in fine hairs but become smooth with maturity. Appearing from late winter to early summer, the inflorescences are dome-shaped flower heads rather than spikes as many other banksias. They measure 7–9 cm (2.8–3.6 in) in diameter, and bear 60 to 100 individual flowers. The inflorescences pass through three colour phases, being initially yellow, then pink, then finally red, before falling away from the head. Flowering is followed by the appearance of one to three follicles
, which remain embedded in the woody base of the flower head. Each bears one or two seeds.
In the Margaret River region, it has been confused with Banksia sessilis var. cordata
as both have prickly foliage and domed flowerheads, however the former grows on deep sand while the latter grows on grey sand over limestone ridges. The embedded follicles of B. ilicifolia compared with the loose ones of B. sessilis are another distinguishing feature.
Banksia subg. Isostylis
. It is the only common member of that subgenus; the two other species are rare and threatened, and are protected under the Environment Protection and Biodiversity Conservation Act 1999
.
The Holly-leaved Banksia was first collected by Robert Brown
in 1801 or 1802 at King George Sound
, and published by him in 1810. The shrubby, coastal ecotype
was incorrectly published as a separate species Banksia aquifolium by John Lindley
in his 1840 A Sketch of the Vegetation of the Swan River Colony
, but this has since been corrected to a taxonomic synonym of B. ilicifolia. No subspecies are recognised. The specific name is derived from the Latin
words ilex "holly" and folium "leaf", hence "holly-leaved".
because of its dome-shaped flower heads. A 1996 cladistic
analysis of the genus by botanists Kevin Thiele
and Pauline Ladiges yielded no information about the circumscription of B. subg. Isostylis, nor of the relationships within it, so George's placement of this species was retained in their arrangement
. That arrangement was not accepted by George, and was largely discarded by him in his 1999 arrangement
. The placement of B. ilicifolia there was unaffected, and can be summarised as follows:
Since 1998, American botanist Austin Mast
and co-authors have been publishing results of ongoing cladistic analyses of DNA sequence
data for the subtribe Banksiinae
, which then comprised genera Banksia and Dryandra. Their analyses suggest a phylogeny
that differs greatly from George's taxonomic arrangement. Banksia ilicifolia and B. oligantha form a clade
, that is they are each other's closest relative, with Banksia cuneata resolving as the next closest relative, suggesting a monophyletic
B. subg. Isostylis; but the clade appears fairly derived
(that it, it evolved relatively recently), suggesting that B. subg. Isostylis may not merit subgeneric rank.
Early in 2007, Mast and Thiele rearranged the genus Banksia by merging Dryandra into it, and published B. subg. Spathulatae
for the taxa having spoon-shaped cotyledon
s; thus B. subg. Banksia was redefined as encompassing taxa lacking spoon-shaped cotyledons. They foreshadowed publishing a full arrangement once DNA sampling of Dryandra was complete; in the meantime, if Mast and Thiele's nomenclatural changes are taken as an interim arrangement, then B. ilicifolia is placed in B. subg. Banksia.
to the Cordinup River east of Albany
. It especially favours low-lying areas.
(Acanthorhynchus superciliosus) in particular prefers this species over other banksias.
A field study carried out at Jandakot Airport south of Perth and published in 1988 found that birds and insects overwhelmingly preferred visiting yellow-coloured flowerheads. The species recorded include several species of honeyeater, including the Red Wattlebird
(Anthochaera carunculata), Western Wattlebird
(A. lunulata), Western Spinebill, Brown Honeyeater
(Lichmera indistincta), New Holland Honeyeater
(Phylidonyris novaehollandiae), White-cheeked Honeyeater
(P. nigra), two species of native bee of the genus Leioproctus
, a beetle of the species Liparetrus, and ant species Iridomyrmex conifer. The yellow flowerheads are also the ones that bear the most nectar.
Banksia ilicifolia has been recorded as a source of nectar for the honey possum
(Tarsipes rostratus) in winter to early summer (May to December), from field studies in the Scott National Park
, replaced by Adenanthos meisneri
in the summer.
Banksia ilicifolia is an obligate phreatophyte, that is, it is reliant upon accessing groundwater
for its survival; it is more closely tied to the water table
unlike the co-occurring Banksia menziesii
and Banksia attenuata
, and must remain in areas where the depth of the water table is less than 8 m (25 ft) below the surface. Recent falls of the water table on the Swan Coastal Plain from use of the Gnangara Mound
aquifer for Perth's water supply as well as years of below average rainfall have seen the population and vigour or Banksia ilicifolia fall considerably (more so than other banksia species) since the mid 1960s.
Banksia ilicifolia has been shown to be highly sensitive to dieback from the soil-borne water mould
Phytophthora cinnamomi
, like many Western Australian banksias. A study of Banksia attenuata woodland 400 km (250 mi) southeast of Perth across 16 years and following a wave of P. cinnamomi infestation showed that B. ilicifolia populations were present but significantly reduced in diseased areas. Specimens in coastal dune vegetation were reported killed by Armillaria luteobubalina
, with mycelial sheaths of the fungus beneath the bark of the root collar.
Seeds do not require any treatment, and take 22 to 41 days to germinate.
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
in the plant Proteaceae
Proteaceae
Proteaceae is a family of flowering plants distributed in the Southern Hemisphere. The family comprises about 80 genera with about 1600 species. Together with the Platanaceae and Nelumbonaceae they make up the order Proteales. Well known genera include Protea, Banksia, Embothrium, Grevillea,...
family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
. Endemic to southwest
Southwest Australia
Southwest Australia is a biodiversity hotspot that includes the Mediterranean forests, woodlands, and scrub ecoregions of Western Australia. The region has a wet-winter, dry-summer Mediterranean climate, one of five such regions in the world...
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 belongs to Banksia subg. Isostylis
Banksia subg. Isostylis
Banksia 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...
, a subgenus of three closely related Banksia
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...
species with 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...
s that are dome-shaped heads rather than characteristic Banksia flower spikes. It is generally encountered as a tree up to 10 m (35 ft) high, with prickly green foliage and yellow and red-tinged flowers. Both the scientific and common names arises from the similarity of its foliage to that of the English holly Ilex.
Although Banksia ilicifolia is variable in habit, with low coastal shrubby forms on the south coast near Albany, there are no recognised varieties as such. Unlike its close relatives, Banksia ilicifolia regenerates after bushfire by regrowing from epicormic buds under its bark. It is rarely cultivated.
Description
Banksia ilicifolia is a fairly variable species. It usually grows as an erect tree up to 10 m (30 ft) in height, but some populations along the south coast consist of small trees or even spreading shrubs.It has a stout trunk up to 50 cm (20 in) in diameter, and thick, fibrous, grey bark. Resembling those of holly, its leaves are a dark shiny green colour, and variously obovate, elliptic, truncate or undulate in shape, and 3–10 cm (1–4 in) long. The leaf edges are generally serrated and quite prickly. The leaves sit atop petioles 0.3–1 cm in length. The upper and undersurface of the leaves are initially covered in fine hairs but become smooth with maturity. Appearing from late winter to early summer, the inflorescences are dome-shaped flower heads rather than spikes as many other banksias. They measure 7–9 cm (2.8–3.6 in) in diameter, and bear 60 to 100 individual flowers. The inflorescences pass through three colour phases, being initially yellow, then pink, then finally red, before falling away from the head. Flowering is followed by the appearance of one to three 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....
, which remain embedded in the woody base of the flower head. Each bears one or two seeds.
In the Margaret River region, it has been confused with Banksia sessilis var. cordata
Banksia sessilis var. cordata
Banksia sessilis var. cordata is a variety of Banksia sessilis , with unusually large leaves and flower heads. It is a rare variety that is restricted to the extreme south-west corner of Western Australia.-Description:...
as both have prickly foliage and domed flowerheads, however the former grows on deep sand while the latter grows on grey sand over limestone ridges. The embedded follicles of B. ilicifolia compared with the loose ones of B. sessilis are another distinguishing feature.
Taxonomy
Because of its dome-shaped flower heads, the Holly-leaved Banksia is placed in the subgenusSubgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
Banksia subg. Isostylis
Banksia subg. Isostylis
Banksia 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...
. It is the only common member of that subgenus; the two other species are rare and threatened, and are protected under the Environment Protection and Biodiversity Conservation Act 1999
Environment Protection and Biodiversity Conservation Act 1999
The Environment Protection and Biodiversity Conservation Act 1999 is an Act of the Parliament of Australia that provides a framework for protection of the Australian environment, including its biodiversity and its natural and culturally significant places...
.
The Holly-leaved Banksia was first collected by Robert Brown
Robert Brown (botanist)
Robert Brown was a Scottish botanist and palaeobotanist who made important contributions to botany largely through his pioneering use of the microscope...
in 1801 or 1802 at King George Sound
King George Sound
King George Sound is the name of a sound on the south coast of Western Australia. Located at , it is the site of the city of Albany.The sound covers an area of and varies in depth from to ....
, and published by him in 1810. The shrubby, coastal ecotype
Ecotype
In evolutionary ecology, an ecotype,Greek: οίκος = home and τύπος = type, coined by Göte Turesson in 1922 sometimes called ecospecies, describes a genetically distinct geographic variety, population or race within species , which is adapted to specific environmental conditions.Typically, ecotypes...
was incorrectly published as a separate species Banksia aquifolium by John Lindley
John Lindley
John Lindley FRS was an English botanist, gardener and orchidologist.-Early years:Born in Catton, near Norwich, England, John Lindley was one of four children of George and Mary Lindley. George Lindley was a nurseryman and pomologist and ran a commercial nursery garden...
in his 1840 A Sketch of the Vegetation of the Swan River Colony
A Sketch of the Vegetation of the Swan River Colony
A Sketch of the Vegetation of the Swan River Colony, also known by its standard botanical abbreviation Sketch Veg. Swan R., is an 1839 article by John Lindley on the flora of the Swan River Colony...
, but this has since been corrected to a taxonomic synonym of B. ilicifolia. No subspecies are recognised. The specific name is derived 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...
words ilex "holly" and folium "leaf", hence "holly-leaved".
Infrageneric placement
George placed B. ilicifolia in subgenus IsostylisBanksia subg. Isostylis
Banksia 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...
because of its dome-shaped flower heads. A 1996 cladistic
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
analysis of the genus by botanists Kevin Thiele
Kevin Thiele
Kevin R. Thiele is curator of the Western Australian Herbarium. His research interests include the systematics of the plant families Proteaceae, Rhamnaceae and Violaceae, and the conservation ecology of grassy woodland ecosystems...
and Pauline Ladiges yielded no information about the circumscription of B. subg. Isostylis, nor of the relationships within it, so George's placement of this species was retained in their arrangement
Thiele and Ladiges' taxonomic arrangement of Banksia
Kevin Thiele and Pauline Ladiges' taxonomic arrangement of Banksia, published in 1996, was a novel taxonomic arrangement that was intended to align the taxonomy of Banksia more closely with the phylogeny that they had inferred from their cladistic analysis of the genus...
. That arrangement was not accepted by George, and was largely discarded by him in his 1999 arrangement
George's taxonomic arrangement of Banksia
Alex George's taxonomic arrangement of Banksia was the first modern-day arrangement for that genus. First published in 1981 in the classic monograph The genus Banksia L.f. , it superseded the arrangement of George Bentham, which had stood for over a hundred years. It was overturned in 1996 by Kevin...
. The placement of B. ilicifolia there was unaffected, and can 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...
(3 sections, 11 series, 73 species, 11 subspecies, 14 varieties) - 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...
- B. ilicifolia
- B. oliganthaBanksia oliganthaBanksia oligantha, commonly known as Wagin Banksia, is an endangered species in the plant family Proteaceae endemic to south west Western Australia. It belongs to Banksia subg. Isostylis, a subgenus of three closely related Banksia species with dome-shaped heads as inflorescences, rather than...
- B. cuneataBanksia cuneataBanksia cuneata, commonly known as Matchstick Banksia or Quairading Banksia, is an endangered species of flowering plants in the Proteaceae family. Endemic to southwest Western Australia, it belongs to Banksia subg...
- B. subg. Banksia
Since 1998, American botanist Austin Mast
Austin Mast
Austin R. Mast is a research botanist. Born in 1972, he obtained a Ph.D. from the University of Wisconsin–Madison in 2000. He is currently an associate professor within the Department of Biological Science at Florida State University , and has been director of FSU's since August 2003.One of his...
and co-authors have been publishing results of ongoing cladistic analyses of DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data for the subtribe Banksiinae
Grevilleoideae
Grevilleoideae is a subfamily of the Proteaceae family of flowering plants. Mainly restricted to the southern hemisphere, it contains around 44 genera and about 950 species. Genera include Banksia, Grevillea and Macadamia.-Description:...
, which then comprised genera Banksia and Dryandra. Their analyses suggest a phylogeny
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
that differs greatly from George's taxonomic arrangement. Banksia ilicifolia and B. oligantha form a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
, that is they are each other's closest relative, with Banksia cuneata resolving as the next closest relative, suggesting a monophyletic
Monophyly
In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...
B. subg. Isostylis; but the clade appears fairly derived
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
(that it, it evolved relatively recently), suggesting that B. subg. Isostylis may not merit subgeneric rank.
Early in 2007, Mast and Thiele rearranged the genus Banksia by merging Dryandra into it, and published B. subg. Spathulatae
Banksia subg. Spathulatae
Banksia subg. Spathulatae is a valid botanic name for a subgenus of Banksia. It was published in 2007 by Austin Mast and Kevin Thiele, and defined as containing all those Banksia species having spathulate cotyledons...
for the taxa having spoon-shaped cotyledon
Cotyledon
A cotyledon , is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...
s; thus B. subg. Banksia was redefined as encompassing taxa lacking spoon-shaped cotyledons. They foreshadowed publishing a full arrangement once DNA sampling of Dryandra was complete; in the meantime, if Mast and Thiele's nomenclatural changes are taken as an interim arrangement, then B. ilicifolia is placed in B. subg. Banksia.
Distribution and habitat
A relatively common species, the Holly-leaved Banksia is widely distributed within south west Western Australia. It occurs on sandy soils within 70 km (45 mi) of the coast, from Mount LesueurMount Lesueur
Mount Lesueur is a near-circular, flat-topped mesa located 21 kilometres from Jurien Bay in Western Australia. It rises above the surrounding lateritic plain of Lesueur National Park which has eroded away around it....
to the Cordinup River east of Albany
Albany, Western Australia
Albany is a port city in the Great Southern region of Western Australia, some 418 km SE of Perth, the state capital. As of 2009, Albany's population was estimated at 33,600, making it the 6th-largest city in the state....
. It especially favours low-lying areas.
Ecology
Several honeyeater species visit and pollinate Banksia ilicifolia. The Western SpinebillWestern Spinebill
The Western Spinebill, Acanthorhynchus superciliosus, is a honeyeater found in the heath and woodland of south-western Western Australia. It ranges between long, and weighs around . It has a black head, gray back and wings, with a red band behind its neck and from its throat to its breast. There...
(Acanthorhynchus superciliosus) in particular prefers this species over other banksias.
A field study carried out at Jandakot Airport south of Perth and published in 1988 found that birds and insects overwhelmingly preferred visiting yellow-coloured flowerheads. The species recorded include several species of honeyeater, including the Red Wattlebird
Red Wattlebird
The Red Wattlebird , also known as Barkingbird or Gillbird, is a honeyeater; a group of birds found mainly in Australia and New Guinea which have highly developed brush-tipped tongues adapted for nectar feeding...
(Anthochaera carunculata), Western Wattlebird
Western Wattlebird
The Western Wattlebird is a honeyeater, a passerine bird in the family Meliphagidae. It was formerly lumped with the Little Wattlebird which it closely resembles. It is restricted to south-western Western Australia....
(A. lunulata), Western Spinebill, Brown Honeyeater
Brown Honeyeater
The Brown Honeyeater is a honeyeater, a group of birds found mainly in Australia and New Guinea which have highly developed brush-tipped tongues adapted for nectar feeding...
(Lichmera indistincta), New Holland Honeyeater
New Holland Honeyeater
The New Holland Honeyeater is a honeyeater species found throughout southern Australia. It was among the first birds to be scientifically described in Australia, and was initially named Certhia novaehollandiae...
(Phylidonyris novaehollandiae), White-cheeked Honeyeater
White-cheeked Honeyeater
The White-cheeked Honeyeater inhabits the east coast and the south-west corner of Australia. It has a large white patch on its cheek, a brown eye, and a yellow panel on its wing.- Description :...
(P. nigra), two species of native bee of the genus Leioproctus
Leioproctus
Leioproctus is a genus in the plaster bee family Colletidae. Its members are primarily found in Australasia and temperate South America, and include the most common native bees in New Zealand...
, a beetle of the species Liparetrus, and ant species Iridomyrmex conifer. The yellow flowerheads are also the ones that bear the most nectar.
Banksia ilicifolia has been recorded as a source of nectar for the honey possum
Honey Possum
The honey possum or tait, its Native Australian name or noolbenger is a tiny Australian marsupial weighing just seven to eleven grams for the male, and eight to sixteen grams for the female—about half the weight of a mouse. Their physical size ranges from a body length of between 6.5 –...
(Tarsipes rostratus) in winter to early summer (May to December), from field studies in the Scott National Park
Scott National Park
Scott National Park is a national park in the South West region of Western Australia , 265 km south of Perth....
, replaced by Adenanthos meisneri
Adenanthos meisneri
Adenanthos meisneri, commonly known as Prostrate Woollybush, is a species of shrub in the family Proteaceae. It is endemic to the south-west of Western Australia....
in the summer.
Banksia ilicifolia is an obligate phreatophyte, that is, it is reliant upon accessing groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
for its survival; it is more closely tied to the water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...
unlike the co-occurring Banksia menziesii
Banksia menziesii
Banksia menziesii, commonly known as firewood banksia, is a species of flowering plant in the genus Banksia. It is a gnarled tree up to 10 m tall, or a lower spreading 1–3 m shrub in the more northern parts of its range. The serrated leaves are dull green with new growth a paler grey...
and Banksia attenuata
Banksia attenuata
Banksia 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...
, and must remain in areas where the depth of the water table is less than 8 m (25 ft) below the surface. Recent falls of the water table on the Swan Coastal Plain from use of the Gnangara Mound
Gnangara Mound
The Gnangara Mound is an area north of Perth, Western Australia where a large mound of sandy soil reaches an elevation of about 60 metres. It stores about 20 cubic kilometres of fresh water, about one hundred times Perth's current annual water usage. It is currently the single most important source...
aquifer for Perth's water supply as well as years of below average rainfall have seen the population and vigour or Banksia ilicifolia fall considerably (more so than other banksia species) since the mid 1960s.
Banksia ilicifolia has been shown to be highly sensitive to dieback from the soil-borne water mould
Water mould
Oömycota or oömycetes form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms . They are filamentous, microscopic, absorptive organisms that reproduce both sexually and asexually...
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...
, like many Western Australian banksias. A study of Banksia attenuata woodland 400 km (250 mi) southeast of Perth across 16 years and following a wave of P. cinnamomi infestation showed that B. ilicifolia populations were present but significantly reduced in diseased areas. Specimens in coastal dune vegetation were reported killed by Armillaria luteobubalina
Armillaria luteobubalina
Armillaria luteobubalina, commonly known as the Australian honey fungus, is a species of mushroom in the family Physalacriaceae. Widely distributed in southern Australia, the fungus is responsible for a disease known as Armillaria root rot, a primary cause of Eucalyptus tree death and forest dieback...
, with mycelial sheaths of the fungus beneath the bark of the root collar.
Cultivation
Banksia ilicifolia 's vulnerability to Phytophthora renders it difficult to grow in areas of summer humidity or high rainfall, such as Australia's east coast. Otherwise, it requires a sunny position and sandy well-drained soil to do well.Seeds do not require any treatment, and take 22 to 41 days to germinate.