Banksia oligantha

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Banksia oligantha
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Proteales
Family: Proteaceae
Genus: Banksia
Subgenus: Banksia subg. Isostylis
Species:
B. oligantha
Binomial name
Banksia oligantha

Banksia 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 characteristic Banksia flower spikes. A shrub or small tree up to 4 m (13 ft) high, it has prickly foliage and pink and cream flowerheads which appear in late Spring (October to December).

Contents

First collected in 1984 near the wheatbelt town of Wagin, Banksia oligantha was officially described in 1987 by Australian botanist Alex George. Several scattered populations survive in fragments of remnant bushland in a region which has been mostly cleared for agriculture. It has been listed as Declared Rare Flora by the Western Australian Government.

Description

Banksia oligantha grows as a single-trunked small tree or as an erect shrub with few main stems. [1] Reports of its maximum height vary from 3 m (9.8 ft) [2] to 5 m (16 ft). [1] When not in flower it is said to look somewhat like Banksia sessilis (Parrot Bush). [3] It has smooth grey bark for the most part, though bark near the base of the trunk may be lightly fissured in older trees. [4] Young stems are covered in hairs, both short and soft, and long and coarse; these are lost with age. [2]

Its leaves are deep green and glossy above, and a pale matte green below. They are roughly oval-shaped, but concave rather than lying flat. There is a sharp point at the tip, and two to four more such points along each margin. They range in length from 1.5 to 3.7 cm (0.59 to 1.46 in), and in width from 0.4 to 2.0 cm (0.16 to 0.79 in), with a petiole 2 to 3 mm (0.079 to 0.118 in) long. Young leaves have a coating of woolly hairs on both sides, but these are soon lost except in pits in the undersurface. [2]

Appearing from October to December (late spring), the flowers occur in dome-shaped heads from 2.5 to 3 cm (0.98 to 1.18 in) in diameter, growing at the ends of branches. These comprise just 20 to 35 individual flowers, enclosed at the base by a whorl of furry involucral bracts 2 to 4 mm (0.079 to 0.157 in) long. As with most other Proteaceae, each flower consists of a perianth comprising four united tepals, and a single pistil, the style of which is initially enclosed within the limb of the perianth, but breaks free at anthesis. In B. oligantha, the perianth is 21 to 22 mm (0.83 to 0.87 in) long, with a limb of 3 to 3.5 mm (0.12 to 0.14 in). Perianth colour grades from red at the base to pale yellow at the limb. The styles are straight, 19 to 24 mm (0.75 to 0.94 in) long, and uniformly cream. [2]

Old flowers soon fall from the flower heads, revealing a woody dome with 1 to 6 follicles embedded in it. These are a mottled grey colour, smooth, and shortly furry. They are oval-shaped, measuring 14 to 19 mm (0.55 to 0.75 in) long by 10 to 15 mm (0.39 to 0.59 in) high by 8 to 9 mm (0.31 to 0.35 in) wide. Each follicle contains up to two winged seeds, from 17 to 20 mm (0.67 to 0.79 in) long. [2] [5]

Banksia oligantha is most easily distinguished from the other two species in B. subg. Isostylis by its smaller leaves, flowers and fruit. [2] Its foliage is also not as prickly as that of B. cuneata . [6]

Taxonomy

Discovery and naming

Banksia oligantha was discovered by Ken Wallace of the Government of Western Australia's Department of Conservation and Land Management (now the Department of Environment and Conservation) in September 1984, during a survey of Wangeling Gully Nature Reserve (Nature Reserve 9098), about 28 km (17 mi) northwest of Wagin. Two months later, on 18 November 1984, Anne Taylor collected from the same location what would become the type specimen. [7] It was recognised as a new species well before a name was published for it, and was referred to in the interim by the informal names "Banksia aff. Cuneata" and "Banksia sp. Wagin". [1] Alex George included an entry for it under the name Banksia oligantha in the 1987 second edition of his The Banksia Book, [4] but the formal publication of that name did not occur until the following year, when George's "New taxa and notes on Banksia L.f. (Proteaceae)" appeared. The specific epithet oligantha derives from the Greek oligo- ("few") and anthos ("flower"), in reference to the low number of flowers per flower head. [7]

The species has an uneventful nomenclatural history: it has no synonyms, and no subspecies or varieties have been published. [8]

Infrageneric placement

George placed B. oligantha in subgenus Isostylis because of its dome-shaped flower heads. [7] A 1996 cladistic analysis of the genus by botanists Kevin Thiele and Pauline Ladiges based on morphology yielded no information about the circumscription of B. subg. Isostylis or the relationships within it, so George's placement of this species was retained. [9] George largely discarded Thiele and Ladiges' changes in his 1999 arrangement, but again B. oligantha's placement was unaffected, and the placement of B. oligantha there can be summarised as follows: [2]

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 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. B. oligantha resolves as sister taxon (that is, next closest relative) to B. ilicifolia, and B. cuneata resolves as sister to these two. This suggests a monophyletic B. subg. Isostylis; yet the clade appears fairly derived (that it, it evolved relatively recently), implying that B. subgenus Isostylis may not merit subgeneric rank. [10] [11] [12]

Early in 2007, Mast and Thiele rearranged the genus Banksia by merging Dryandra into it, and publishing B. subg. Spathulatae for the taxa having spoon-shaped cotyledons; 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. oligantha is placed in B. subg. Banksia. [13]

Phylogeny

Relationships between B. oligantha and the other members of B. subg. Isostylis still remain unclear. Though Mast's studies found B. cuneata to be the most basal of the three species, [11] a 2004 study of genetic divergence within the subgenus yielded both other possibilities: some analyses suggested B. ilicifolia as basal, while others suggested B. oligantha. Further complicating the situation is the southernmost (and closest) population of B. cuneata, which has both genetic and phenetic affinities with B. oligantha. The origin of this population is unknown: it might have arisen through hybridisation, or it may be a transitional or even ancestral form. Finally, biogeographical factors suggest that B. ilicifolia would be the most basal of the three species: it occurs in the High Rainfall Zone where relictual species are most common, whereas the others are restricted to the Transitional Rainfall Zone, where more recently evolved species are most common. [14]

Distribution and habitat

Distribution Banksia oligantha map.png
Distribution

Banksia oligantha occurs over a range of about 100 kilometres (62 miles) in southern parts of the Avon Wheatbelt region of the Southwest Botanical Province of Western Australia. Four populations are known, containing about 1,700 adult plants in total: [1]

The species grows in sand dunes of white, [2] white-grey [1] or yellow-brown sand, amongst a system of ephemeral salt creeks. [15] Populations occur both in low-lying areas near creeks, and atop dunes. [1] The vegetation has been described as low open woodland over heath, [1] and as tall open shrubland [2] with some scattered trees. [15]

Ecology

Little has been published on the ecology of B. oligantha. Its lifespan is probably around 10 to 30 years. [1]

Six species of honeyeater have been observed feeding at its flowers, as have insects including honeybees, ants, butterflies, beetles and native bees. Both birds and insects function as pollinators, [16] but honeybees are probably not very effective: in one study only about 4% of honeybees collected pollen, and they tended to move from inflorescence to inflorescence on the same plant, rather than moving between plants. [1]

Assessments of the mating system of this species have found that outcrossing rates vary between populations, with populations in disturbed environments tending to be more inbred than populations in relatively intact bushland. This has been attributed to a range of causes. Firstly, the higher density of disturbed populations leads to greater rates of mating between neighbouring plants, resulting in more genetic structure and thus more effective selfing. Secondly, disturbed populations usually lack an understorey, and so cannot support a resident population of honeyeaters; instead, they rely upon sporadic visits for pollination. The greatly reduced pollination rates means fewer outcrossing fertilisations on average, leading to less selection against inbred fertilisations. [16]

Like many plants in south-west Western Australia, B. oligantha is adapted to an environment in which bushfire events are relatively frequent. Most Banksia species can be placed in one of two broad groups according to their response to fire: reseeders are killed by fire, but fire also triggers the release of their canopy seed bank, thus promoting recruitment of the next generation; resprouters survive fire, resprouting from a lignotuber or, more rarely, epicormic buds protected by thick bark. B. oligantha is a reseeder; it has thin bark, and lacks a lignotuber, so it is killed by fire. However, the species is weakly serotinous: fire triggers seed release, yet seed release still occurs in the absence of fire. [1]

Seed germination rates are quite high. One study found germination rates better than 77% in most batches tested. Seed is likely to remain viable for a long time, as seed of the closely related B. cuneata remains viable for around ten years. [1]

Conservation

Banksia oligantha is listed as an endangered species under the federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), [17] and as rare under Western Australia's Wildlife Conservation Act 1950 . [18] These rankings are due to its small and severely fragmented distribution, and the ongoing degradation of its habitat. [3] Threats include grazing by sheep and rabbits, drought, the drift of aerosol chemicals from surrounding farmland, invasion by weeds, and rising salinity. Studies have shown it to be moderately susceptible to Phytophthora cinnamomi dieback. [1] [3]

Cultivation

Banksia oligantha is rarely seen in cultivation, though it is said to merit more consideration than it receives. It is a fast-growing plant that flowers prolifically, producing "lovely masses of matchstick-like cream flowers". However, its prickly foliage makes it unsuitable for growth near paths, it is prone to lose branches in strong wind, and it is often attacked by woodboring beetles. [5]

Propagation is by seed, but these are hard to obtain. [5] Seeds do not require any treatment before sowing, and take 37 to 40 days to germinate. [19] Propagation by cutting has not been attempted, but might be possible, since the closely related B. cuneata has been propagated this way, albeit with unpredictable results. The plant should be grown in deep, acidic to neutral sand at a sheltered site. It is recommended to prune it when young, to encourage branching. [5]

Related Research Articles

<i>Banksia</i> Genus of flowering plants in the family Proteaceae

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. Banksias range in size from prostrate woody shrubs to trees up to 30 metres tall. They are found in a wide variety of landscapes: sclerophyll forest, (occasionally) rainforest, shrubland, and some more arid landscapes, though not in Australia's deserts.

<i>Banksia <span style="font-style:normal;">subg.</span> Isostylis</i> Subgenus in the family Proteaceae from southwest Western Australia

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. Dryandra, but structurally more like reduced versions of the "flower spikes" characteristic of most other Banksia taxa.

<i>Banksia ilicifolia</i> Tree in the family Proteaceae endemic to southwest Western Australia

Banksia ilicifolia, commonly known as holly-leaved banksia, 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.

<i>Banksia cuneata</i> Endangered species of flowering plant

Banksia cuneata, commonly known as matchstick banksia or Quairading banksia, is an endangered species of flowering plant in the family Proteaceae. Endemic to southwest Western Australia, it belongs to Banksia subg. Isostylis, a sub-genus of three closely related Banksia species with inflorescences or flower clusters that are dome-shaped heads rather than characteristic Banksia flower spikes. A shrub or small tree up to 5 m (16 ft) high, it has prickly foliage and pink and cream flowers. The common name Matchstick Banksia arises from the blooms in late bud, the individual buds of which resemble matchsticks. The species is pollinated by honeyeaters (Meliphagidae).

Taxonomy of <i>Banksia</i> Classification of the plant genus Banksia

As with other flowering plants, the taxonomy of Banksia has traditionally been based on anatomical and morphological properties of the Banksia flower, fruiting structure and seed, along with secondary characteristics such as leaf structure and growth habit. Increasingly, molecular evidence from DNA is providing important new insights into relationships within the genus and between this and other genera in the Proteaceae.

<i>Banksia aculeata</i> Shrub of the family Proteaceae native to the southwest of Western Australia.

Banksia aculeata, commonly known as prickly banksia, is a species of plant of the family Proteaceae native to the Stirling Range in the southwest of Western Australia. A shrub up to 2 m (7 ft) tall, it has dense foliage and leaves with very prickly serrated margins. Its unusual pinkish, pendent (hanging) flower spikes, known as inflorescences, are generally hidden in the foliage and appear during the early summer. Although it was collected by the naturalist James Drummond in the 1840s, Banksia aculeata was not formally described until 1981, by Alex George in his monograph of the genus.

<i>Banksia caleyi</i> Australian species of shrub, the red lantern banksia

Banksia caleyi, commonly known as Caley's banksia or red lantern banksia, is a species of woody shrub of the family Proteaceae native to Western Australia. It generally grows as a dense shrub up to 2 m (7 ft) tall, has serrated leaves and red, pendent (hanging) inflorescences which are generally hidden in the foliage. First described by Scottish naturalist Robert Brown in 1830, Banksia caleyi was named in honour of the English botanist George Caley. No subspecies are recognised. It is one of three or four related species with hanging inflorescences, which is an unusual feature within the genus.

<i>Banksia canei</i> Shrub species endemic to Australia

Banksia canei, commonly known as the mountain banksia, is a species of shrub that is endemic to southeastern Australia. It is generally encountered as a many-branched shrub that grows up to 3 m (10 ft) high, with narrow leaves and the yellow inflorescences appearing from late summer to early winter. The old flowers fall off the spikes and up to 150 finely furred follicles develop, which remain closed until burnt in a bushfire. Each follicle bears two winged seeds. Response to fire is poorly known, although it is thought to regenerate by seed. Birds such as the yellow-tufted honeyeater and various insects forage among the flower spikes. It is frost tolerant in cultivation, but copes less well with aridity or humidity and is often short-lived in gardens. One cultivar, Banksia 'Celia Rosser', was registered in 1978, but has subsequently vanished.

<i>Banksia dryandroides</i> Species of shrub in the family Proteaceae from the south coast of Western Australia

Banksia dryandroides, the dryandra-leaved banksia, is a species of small shrub in the plant genus Banksia. The Noongar peoples know the tree as manyat. It occurs in shrubland, woodland and kwongan on the south coast of Western Australia between Narrikup and Beaufort Inlet. The species is placed alone in series B. ser. Dryandroideae.

<i>Banksia elegans</i> Species of shrub in the family Proteaceae endemic to Western Australia

Banksia elegans, commonly known as the elegant banksia, is a species of woody shrub that is endemic to a relatively small area of Western Australia. Reaching 4 m (13 ft) high, it is a suckering shrub that rarely reproduces by seed. The round to oval yellow flower spikes appear in spring and summer. Swiss botanist Carl Meissner described Banksia elegans in 1856. It is most closely related to the three species in the subgenus Isostylis.

<i>Banksia lemanniana</i> Shrub of the family Proteaceae native to Western Australia

Banksia lemanniana, the yellow lantern banksia or Lemann's banksia, is a species of flowering plant in the family Proteaceae, native to Western Australia. It generally grows as an open woody shrub or small tree to 5 m (16 ft) high, with stiff serrated leaves and unusual hanging inflorescences. Flowering occurs over summer, the greenish buds developing into oval flower spikes before turning grey and developing the characteristic large woody follicles. It occurs within and just east of the Fitzgerald River National Park on the southern coast of the state. B. lemanniana is killed by bushfire and regenerates from seed.

<i>Banksia plagiocarpa</i> Species of shrub in the family Proteaceae native to Queensland

Banksia plagiocarpa, commonly known as the Dallachy's banksia or blue banksia, is a species of shrub or tree in the plant genus Banksia. It occurs only on Hinchinbrook Island, Queensland and the immediately adjacent mainland. First collected in 1867, Banksia plagiocarpa was not described until 1981, when Alex George named it in his monograph of the genus Banksia. Genetic studies show it to be related to Banksia aquilonia, Banksia oblongifolia and Banksia robur.

<i>Banksia saxicola</i> Species of shrub in the family Proteaceae native to Victoria (Australia)

Banksia saxicola, the rock banksia or Grampians banksia, is a species of tree or shrub in the plant genus Banksia. It occurs in Victoria in two distinct populations, one in The Grampians and the other on Wilsons Promontory. Formerly considered to be a form of B. integrifolia, it was described as a distinct species by Alex George in 1981. It is most closely related to Banksia marginata.

<i>Banksia violacea</i> Species of plant

Banksia violacea, commonly known as violet banksia, is a species of shrub or tree in the plant genus Banksia. It generally grows as a small shrub to 1.5 m (5 ft) high with fine narrow leaves, and is best known for its unusually coloured dark purple-violet inflorescences. The colour of the inflorescences, short leaves, and flattened follicles which are sticky when young, help identify this species from others in the field. It is found in low shrubland in southern regions of Western Australia from Esperance in the east to Narrogin in the west, growing exclusively in sandy soils.

<i>Banksia epica</i> A shrub in the family Proteaceae that grows on the south coast of Western Australia

Banksia 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 (11½ ft) high. It is known only from two isolated populations in the remote southeast of the state, near the western edge of the Great Australian Bight. Both populations occur among coastal heath on cliff-top dunes of siliceous sand.

<i>Banksia <span style="font-style:normal;">ser.</span> Cyrtostylis</i> Taxonomic series in the genus Banksia

Banksia ser. Cyrtostylis is 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.

<i>Banksia acanthopoda</i> Species of shrub in Western Australia

Banksia acanthopoda is a species of shrub in the family Proteaceae. It grows as a small spreading shrub to 2 m high and has prickly leaves and yellow composite flower heads, called inflorescences, composed of 50 to 60 individual yellow flowers. Flowering takes place in the southern hemisphere winter. Endemic to Western Australia, it occurs only in a few populations in the vicinities of Woodanilling, Katanning and Darkan. Because of its rarity, it is classed as "Priority Two" conservation flora by Western Australia's Department of Environment and Conservation.

Robert Brown's taxonomic arrangement of Banksia was published in his book of 1810, Prodromus Florae Novae Hollandiae et Insulae Van Diemen, and expanded in the supplement to that publication, Supplementum Primum Prodromi Florae Novae Hollandiae, in 1830. It was the first survey of Banksia species to be published, and included descriptions of a number of previously undescribed species.

Georges taxonomic arrangement of Banksia 1981 and 1996 arrangements of the Australian endemic plant genus 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. (Proteaceae), it superseded the arrangement of George Bentham, which had stood for over a hundred years. It was overturned in 1996 by Kevin Thiele and Pauline Ladiges, but restored by George in 1999. A recent publication by Austin Mast and Kevin Thiele suggests that it will soon be overturned again.

<i>Banksia spinulosa <span style="font-style:normal;">var.</span> spinulosa</i> Variety of shrub in the family Proteaceae from the east coast of Australia

Banksia spinulosa var. spinulosa is a shrub that grows along the east coast of Australia, in Queensland and New South Wales.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Department of Environment and Conservation (2008). "Wagin banksia (Banksia oligantha) Recovery Plan". Interim Recovery Plan No. 220. Retrieved 20 January 2010.{{cite journal}}: Cite journal requires |journal= (help)
  2. 1 2 3 4 5 6 7 8 9 George, Alex S. (1999). "Banksia". In Wilson, Annette (ed.). Flora of Australia . Vol. 17B. CSIRO Publishing / Australian Biological Resources Study. pp. 175–251. ISBN   0-643-06454-0.
  3. 1 2 3 Brown, Andrew (2006). "Endangered: Wagin Banksia". Landscope. 22 (1): 18.
  4. 1 2 George, Alex S. (1987). The Banksia Book (2nd ed.). Kenthurst, New South Wales: Kangaroo Press (in association with the Society for Growing Australian Plants). p. 231. ISBN   0-86417-006-8.
  5. 1 2 3 4 Collins, Kevin; et al. (2008). Banksias. Melbourne, Victoria: Bloomings Books. pp. 53, 304–05. ISBN   978-1-876473-68-6.
  6. ↑ Kershaw, K.; Liber, C. (2004). "Threatened Banksias #4 & #5: Banksia cuneata & B. oligantha". Banksia Study Group Newsletter. 5 (3): 1–5. ISSN   1444-285X.
  7. 1 2 3 George, Alex (1988). "New taxa and notes on Banksia L.f. (Proteaceae)". Nuytsia . 6 (3): 309–317.
  8. ↑ "Banksia oligantha A.S.George". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.
  9. ↑ Thiele, Kevin; Ladiges, Pauline Y. (1996). "A cladistic analysis of Banksia (Proteaceae)". Australian Systematic Botany . 9 (5): 661–733. doi:10.1071/SB9960661.
  10. ↑ Mast, Austin R. (1998). "Molecular systematics of subtribe Banksiinae (Banksia and Dryandra; Proteaceae) based on cpDNA and nrDNA sequence data: implications for taxonomy and biogeography". Australian Systematic Botany. 11 (4): 321–42. doi:10.1071/SB97026.
  11. 1 2 Mast, Austin R.; Givnish, Thomas J. (2002). "Historical biogeography and the origin of stomatal distributions in Banksia and Dryandra (Proteaceae) based on Their cpDNA phylogeny". American Journal of Botany . 89 (8): 1311–23. doi: 10.3732/ajb.89.8.1311 . ISSN   0002-9122. PMID   21665734.
  12. ↑ Mast, Austin R.; Eric H. Jones & Shawn P. Havery (2005). "An assessment of old and new DNA sequence evidence for the paraphyly of Banksia with respect to Dryandra (Proteaceae)". Australian Systematic Botany. CSIRO Publishing / Australian Systematic Botany Society. 18 (1): 75–88. doi:10.1071/SB04015.
  13. ↑ Mast, Austin R. & Kevin Thiele (2007). "The transfer of Dryandra R.Br. to Banksia L.f. (Proteaceae)". Australian Systematic Botany. 20: 63–71. doi:10.1071/SB06016.
  14. ↑ Broadhurst, Linda M.; Coates, David J. (2004). "Genetic divergence among and diversity within two rare Banksia species and their common close relative in the subgenus Isostylis R.Br. (Proteaceae)". Conservation Genetics. 5 (6): 837–46. doi:10.1007/s10592-004-5268-9. S2CID   39559876.
  15. 1 2 Taylor, Anne; Hopper, Stephen (1988). The Banksia Atlas (Australian Flora and Fauna Series Number 8). Canberra: Australian Government Publishing Service. pp. 86–87. ISBN   0-644-07124-9.
  16. 1 2 Coates, David J.; Sampson, Jane F.; Yates, Colin J. (2007). "Plant mating systems and assessing population persistence in fragmented landscapes". Australian Journal of Botany. 55 (3): 239–49. doi:10.1071/BT06142.
  17. ↑ Banksia oligantha — Wagin Banksia , Species Profile and Threats Database , Department of the Environment and Heritage, Australia.
  18. ↑ "Banksia oligantha A.S.George". FloraBase . Western Australian Government Department of Biodiversity, Conservation and Attractions.
  19. ↑ Sweedman, Luke; Merritt, David; et al. (2006). Australian seeds: a guide to their collection, identification and biology. CSIRO Publishing. p. 203. ISBN   0-643-09298-6.
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