Banksia ilicifolia
Holly-leaved banksia | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Order: | Proteales |
Family: | Proteaceae |
Genus: | Banksia |
Subgenus: | Banksia subg. Isostylis |
Species: | B. ilicifolia
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Binomial name | |
Banksia ilicifolia | |
Synonyms[1] | |
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Banksia ilicifolia, commonly known as holly-leaved banksia,[2] is a tree in the family Proteaceae. Endemic to southwest Western Australia, it belongs to Banksia subg. Isostylis, a subgenus of three closely related Banksia species with inflorescences that are dome-shaped heads rather than characteristic Banksia flower spikes. It is generally a tree up to 10 metres (33 ft) tall with a columnar or irregular habit. Both the scientific and common names arise from the similarity of its foliage to that of the English holly Ilex aquifolium; the glossy green leaves generally have very prickly serrated margins, although some plants lack toothed leaves. The inflorescences are initially yellow but become red-tinged with maturity; this acts as a signal to alert birds that the flowers have opened and nectar is available.
Robert Brown described Banksia ilicifolia in 1810. Although Banksia ilicifolia is variable in growth form, with low coastal shrubby forms on the south coast near Albany, there are no recognised varieties as such. Distributed broadly, the species is restricted to sandy soils. Unlike its close relatives which are killed by fire and repopulate from seed, Banksia ilicifolia regenerates after bushfire by regrowing from epicormic buds under its bark. It is rarely cultivated.
Description
Banksia ilicifolia is a variable species. It usually grows as an erect tree up to 10 metres (33 ft) in height, but some populations along the south coast consist of small trees or even spreading shrubs.[3] It is generally a 5 metres (16 ft) high small tree in the Margaret River region.[4] The leaves arising from many short branchlets make a dense foliage close to the trunk and branches.[5]
Banksia ilicifolia has a stout trunk up to 50 cm (19.5 in) in diameter, and rough, fibrous, grey bark which is up to 2 cm (1 in) thick.[3] New growth takes place mainly in summer.[6] Young branchlets are covered in hair which they lose after two or three years. Leaves grow on stems less than two years of age, and are arranged in a scattered pattern along the stems although crowded at the apices (branchlet tips). Resembling those of holly, its leaves are a dark shiny green colour, and variously obovate (egg-shaped), elliptic, truncate or undulate (wavy) in shape, and 3–10 cm (1–4 in) long. Generally serrated, the leaf edges have up to 14 prickly "teeth" separated by broad v- to u-shaped sinuses along each side, although some leaves have margins lacking teeth. The leaves sit atop petioles 0.3–1 cm (0.12–0.39 in) in length. The upper and undersurface of the leaves are initially covered in fine hairs but become smooth with maturity. Flowering takes place from late winter to early summer. The inflorescences are dome-shaped flower heads rather than spikes as many other banksias, and arise from stems that are around a year old. No lateral branchlets grow outwards from the node where the flower head arises.[3] The flower heads measure 7–9 cm (3–3.5 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. One to three follicles develop from fertilised flowers, and remain embedded in the woody base of the flower head. Each follicle bears one or two seeds.[7]
The cotyledon leaves are a dull green with no visible nerves or markings. Transversely elliptic in shape, they measure 8 to 13 mm long by 12 to 18 mm wide and range from convex to concave. The pointed spreading auricles are 1.5 mm long. The cotyledon leaves sit atop the stout hypocotyl, which is green and smooth. The seedling leaves are crowded above the cotyledons. Resembling those of B. coccinea, they are lined with triangular lobes or "teeth" (with a u- or v-shaped sinus) and obovate to broadly lanceolate in shape. The first set of leaves measure 1 to 2.5 cm (0.39 to 0.98 in) in length and around 1 cm (0.5 in) in width, with three or four lobes in each margin. Both upper and lower seedling leaf surfaces are covered in spreading hairs, as is the seedling stem. Juvenile leaves are obovate to truncate or mucronate with triangular lobes and measure 4 to 10 cm (1.5 to 4 in) long by 1.5 to 3.5 cm (0.59 to 1.38 in) wide. These lobes are smaller toward the petiole and apex of the leaf.[3]
In the Margaret River region, Banksia ilicifolia 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.[4]
Taxonomy
Specimens of B. ilicifolia were first collected by Scottish surgeon
Brown eventually published the species in his 1810 work
The shrubby, coastal
In 1891,
Infrageneric placement
The unranked group Isostylis, with its one species, was reclassified as a
A 1996 cladistic analysis of the genus by botanists Kevin Thiele and Pauline Ladiges assumed the status B. subg. Isostylis as a subgenus and earliest offshoot within Banksia, so George's placement of B. ilicifolia was retained in their arrangement.[19] The placement of B. ilicifolia was unchanged in George's 1999 arrangement, and can be summarised as follows:[7]
- Banksia
- B. subg. Banksia (3 sections, 11 series, 73 species, 11 subspecies, 14 varieties)
- B. subg. Isostylis
- B. ilicifolia
- B. oligantha
- B. cuneata
Since 1998, American botanist
Distribution and habitat
A relatively common species, the holly-leaved banksia is widely distributed within south west Western Australia. It occurs within 70 km (43 mi) of the coast, from Mount Lesueur to Augusta, and then east to the Cordinup River east of Albany.[6] In the Margaret River region, it grows on yellow sand plains behind the Leeuwin-Naturaliste Ridge.[4] Almost all occurrences are to the west (seaward) side of the Darling Scarp, although there are two outlying populations – one near Collie east of Bunbury and the other in the Tonbridge-Lake Muir area near Manjimup. Along the south coast, there is one inland population at Sheepwash Nature Reserve near Narrikup northwest of Albany.[6] The annual rainfall over its distribution ranges from 600 to 1,100 mm (24 to 43 in).[23]
Banksia ilicifolia grows exclusively on sandy soils; its range ends where heavy soils are evident.
The holly-leaved banksia gives its name to the Banksia ilicifolia woodlands ('community type 22'), a possibly threatened ecological community found in the Bassendean and Spearwood systems in the central Swan Coastal Plain north of Rockingham. These are low-lying areas which are seasonally waterlogged. The habitat is open woodland and with an open understorey, and such trees as B. ilicifolia, B. attenuata and stout paperbark (Melaleuca preissiana).[25]
Banksia ilicifolia is a component of the critically endangered Assemblage of Tumulus Springs (organic mound springs) of the Swan Coastal Plain community north of Perth, which is characterised by a permanently moist peaty soil. The dominant trees include M. preissiana, swamp banksia (B. littoralis) and flooded gum (Eucalyptus rudis), with understorey ferns such as bracken (Pteridium esculentum) and Cyclosorus interruptus, and shrubs swamp peppermint (Taxandria linearifolia) and Astartea fascicularis.[26]
Ecology
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.[27] Several honeyeater species visit and pollinate Banksia ilicifolia. The western spinebill (Acanthorhynchus superciliosus) in particular prefers this species over other banksias.[28]
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), singing honeyeater, (Lichenostomus virescens), as well as the twenty-eight parrot (Barnardius zonarius semitorquatus)[6] two species of native bee of the genus Leioproctus, a beetle of the genus Liparetrus, and ant species Iridomyrmex conifer. The yellow flowerheads are also the ones that bear the most nectar, and are greatly preferred by red wattlebirds.[29]
An analysis of the invertebrate population in the
Hand-pollination experiments on wild populations near Perth showed that Banksia ilicifolia is self-compatible, although progeny produced have less vigour and seed production is reduced.[30] Further experiments show that seedlings of outcrossing with plants greater than 30 kilometres (19 mi) apart are more vigorous and adaptable, suggesting that plants breeding within small fragmented populations are subject to reduced vigour and genetic inbreeding.[31]
Banksia ilicifolia regenerates after bushfire by regrowing from epicormic shoots under its bark. Follicles open and release seeds after several years.[3] It is weakly serotinous, like eight other Banksia species, all of which tend to occur in Western Australia's southwestern corner.[32] The other two species of the subgenus Isostylis are killed by fire and regenerate by seed.[17]
All banksias have developed proteoid or cluster roots in response to the nutrient-poor conditions of Australian soils (particularly lacking in phosphorus).[33] The plant develops masses of fine lateral roots which form a mat-like structure underneath the soil surface. These enable it to extract nutrients as efficiently possible out of the soil. A study of three co-occurring species in Banksia woodland in southwestern Australia—Banksia menziesii, B. attenuata and B. ilicifolia—found that all three develop fresh roots in September after winter rainfall, and that the bacteria populations associated with the root systems of B. menziesii differ from the other two, and that they also change depending on the age of the roots.[34] Along with its shallow lateral roots, Banksia ilicifolia sinks one or more deep taproots seeking the water table.[35] It is an obligate phreatophyte, that is, it is reliant upon accessing groundwater for its survival; it is more closely tied to the water table than the co-occurring B. menziesii and B. attenuata, and must remain in areas where the depth of the water table is less than 8 m (26 ft) below the surface.[36] Recent falls of the water table on the Swan Coastal Plain from use of the Gnangara Mound aquifer for Perth's water supply combined with 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.[37]
Like many Western Australian banksias, Banksia ilicifolia has been shown to be highly sensitive to dieback from the soil-borne
Cultivation
Rarely cultivated,
References
- ^ a b "Banksia ilicifolia". Australian Plant Census. Retrieved 5 May 2020.
- Department of Biodiversity, Conservation and Attractions.
- ^ ISSN 0085-4417.
- ^ ISBN 978-0-9577729-7-7.
- ^ a b Tassone, R.A.; Maier, J.D. (1997). "Abundance of Arthropods in Tree Canopies of Banksia Woodland on the Swan Coastal Plain". Journal of the Royal Society of Western Australia. 80: 281–86.
- ^ ISBN 978-0-644-07124-6.
- ^ ISBN 978-0-643-06454-6.
- ^ "Banksia ilicifolia R.Br". Robert Brown's Australian Botanical Specimens, 1801–1805 at the BM. Perth, Western Australia: FloraBase, Western Australian Herbarium. Retrieved 3 June 2012.
- ^ Pignatti-Wikus, Erika; Reidl-Dorn, Christa; Mabberley, David (2000). "Ferdinand Bauer's field drawings of endemic Western Australian plants made at King George Sound and Lucky Bay, December 1801 – January 1802. I: Families Brassicaceae, Goodenaceae p.p., Lentibulariaceae, Campanulaceae p.p., Orchidaceae, Pittosporaceae p.p., Rutaceae p.p., Stylidaceae, Xyridaceae". Rendiconti Lincei: Scienze Fisiche e Naturali. s.9, v.11 (2): 69–109.
- ISBN 978-0-642-27739-8.
- ^ Brown, Robert (1810). Prodromus Florae Novae Hollandiae et Insulae Van Diemen. London, United Kingdom: Taylor. p. 396.
- ^ a b Bentham, George (1870). "Banksia". Flora Australiensis. Vol. 5: Myoporineae to Proteaceae. London, United Kingdom: L. Reeve & Co. pp. 541–62.
- ^ Kuntze, Otto (1891). Revisio generum plantarum. Vol. 2. Leipzig: Arthur Felix. pp. 581–582.
- JSTOR 4107078.
- JSTOR 4111642.
- Prodromus systematis naturalis regni vegetabilis. Vol. 14. Paris, France: Sumptibus Sociorum Treuttel et Wurtz.
- ^ S2CID 39559876.
- ^ PMID 21665734.
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- doi:10.1071/SB97026.
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- ^ ISBN 978-0-86417-818-3.
- ^ a b Mansergh, Nicholas (1999). "Banksia ilicifolia". Australian Plants Online. Australian Native Plants Society (Australia). Retrieved 1 June 2012.
- ^ Species and Communities Branch (13 April 2012). "Priority Threatened Ecological Communities for Western Australia: Version 17". Perth, Western Australia: Department of Environment and Conservation, Western Australian Government. Retrieved 1 June 2012.
- ^ English, Val; Blyth, John (February 2000). "Assemblages of Organic Mound (Tumulus) Springs of the Swan Coastal Plain Interim Recovery Plan 2000–2003". Threatened species & ecological communities. Canberra, Australian Capital Territory: Department of Sustainability, Environment, Water, Population and Communities, Australian Government. Retrieved 3 June 2012.
- doi:10.1071/AM07003.
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- doi:10.1071/BT04011.
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- ^ Beadle, Noel C. (1968). "Some aspects of the ecology and physiology of Australian xeromorphic plants". Australian Journal of Science. 30: 348–55.
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- PMID 19021880.
- ^ Groom, P. K.; Froend, R. H.; Mattiske, E. M.; Gurner, R. P. (2001). "Long-term Changes in Vigour and Distribution of Banksia and Melaleuca Overstorey Species on the Swan Coastal Plain". Journal of the Royal Society of Western Australia. 84: 63–69.
- .
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- doi:10.1071/BT97012.
- ISBN 978-0-85091-143-5.
- ISBN 978-0-643-09298-3.
- ISBN 978-1-876473-68-6.
External links
- "Banksia ilicifolia R.Br". Flora of Australia Online. Department of the Environment and Heritage, Australian Government.
- "Banksia ilicifolia R.Br". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.