Banksia prionotes

taxobox
name = Acorn Banksia

---

image_caption = "Banksia prionotes", Reabold Hill, Bold Park Floreat, WA
regnum = Plantae
unranked_divisio = Angiosperms
unranked_classis = Eudicots
ordo = Proteales
familia = Proteaceae
genus = "Banksia"
subgenus = "Banksia" subg. "Banksia"
sectio = "Banksia" sect. "Banksia"
series = "Banksia" ser. "Crocinae"
species = "B. prionotes"
binomial = Banksia prionotes
binomial_authority = Lindl.|

"Banksia prionotes", commonly known as Acorn Banksia or Orange Banksia, is a species of woody shrub or tree of the genus "Banksia" in the Proteaceae family. It is native to the southwest of Western Australia. It can reach up to 10 m (30 ft) in height, though can be much smaller in more exposed areas or in the north of its range. It has serrated, dull green leaves and large, bright flower spikes, initially white then opening to a bright orange. It gains its common name as the partly opened inflorescences resemble acorns. These make it a popular garden plant, and also of importance to the cut flower industry.

It was first described in 1840 by John Lindley, probably from material collected by James Drummond the previous year. There are no recognised varieties though it has been known to hybridise with "Banksia hookeriana". Widely distributed, "B. prionotes" is found from Shark Bay (25° S) in the north, south as far as Kojonup (33°50′S). It grows exclusively in sandy soils, and is usually the dominant plant in scrubland or low woodland. The Acorn Banksia is pollinated by and provides food for a wide array of vertebrate and invertebrate animals in the autumn and winter months, and is an important source of food for honey-eaters, and is critical to their survival in the Avon Wheatbelt region, where it is the only nectar-producing plant in flower at some times of the year.

Description

It grows as a tree up to 10 m (30 ft) high in southern parts of its distribution, but in northern parts is usually a smaller, spreading shrub or small tree, reaching about 4 m (13 ft) in height.cite web | title = Banksia prionotes | url = http://asgap.org.au/b-pri.html | publisher = ASGAP | accessdate = 2007-09-10] It has thin grey smooth or grooved bark, and tomentose young stems. The leaves are from 15–27 cm (6–11 in) long, and 1–2 cm (⅓–⅔ in) width, with dentate leaf margins made up of triangular lobes, and often an undulate surface. Flowers occur in a typical "Banksia" flower spike, an inflorescence made up of hundreds of flowers densely packed around a cylindrical axis. "B. prionotes" has cream flowers with an orange limb. This creates the effect of a cream inflorescence that progressively turns bright orange as anthesis sweeps through the inflorescence. Af the conclusion of flowering, the old flower parts fall away, revealing the axis, which may be embedded with up to 60 follicles.The genus Banksia L.f. (Proteaceae)] cite encyclopedia | last = George | first = Alex S. | authorlink = Alex George | year = 1999 | title = Banksia | editor = Wilson, Annette (ed.) | encyclopedia = Flora of Australia | volume = Volume 17B: Proteaceae 3: Hakea to Dryandra | pages = 175–251 | location = Collingwood, Victoria | publisher = CSIRO Publishing / Australian Biological Resources Study | id = ISBN 0-643-06454-0]

Taxonomy

"B. prionotes" was first published by John Lindley in the January 1840 issue of his "A Sketch of the Vegetation of the Swan River Colony"; hence the species' full name is "Banksia prionotes" Lindl..APNI | name = "Banksia prionotes" Lindl. | id = 55048] Lindley did not specify the type material upon which he based the species, but "A Sketch" is based primarily upon the collections of James Drummond.A Sketch of the Vegetation of the Swan River Colony] A sheet at "B. prionotes" at CGE, labelled "Swan River, Drummond, 1839", has since been designated the lectotype. Lindley also made no mention of the etymology of the specific epithet "prionotes"; George has confirmed the obvious, however: it is from the Greek "prion" ("saw") and "-otes" ("quality"), in reference to the serrated leaf margins.The Banksia Book]

The species has had a fairly uneventful taxonomic history. No subspecies or variety have been published, and it has no taxonomic synonyms. Its only nomenclatural synonym is "Sirmuellera prionotes" (Lindl.) Kuntze, which arose from Otto Kuntze's unsuccessful 1891 attempt to transfer "Banksia" into the new name "Sirmuellera".APNI | name = "Sirmuellera prionotes" (Lindl.) Kuntze | id = 23235] When Carl Meissner published his infrageneric arrangement of "Banksia" in 1856, he placed "B. prionotes" in "B." sect. "Eubanksia" because its inflorescence is a spike rather than a domed head, and in series "B." ser. "Salicinae",cite encyclopedia | author = Meissner, Carl | year = 1856 | chapter = Proteaceae | editor = de Candolle, A. P. | encyclopedia = Prodromus systematis naturalis regni vegetabilis | volume = 14 | location = Paris | publisher = Sumptibus Sociorum Treuttel et Wurtz] a large series that is now considered quite heterogeneous. This series was discarded in the 1870 arrangement of George Bentham; instead, "B. prionotes" was placed in "B." sect. "Orthostylis", which Bentham defined as consisting of those "Banksia" species with flat leaves with serrated margins, and rigid, erect styles that "give the cones after the flowers have opened a different aspect".cite encyclopedia | author = Bentham, George | year = 1870 | title = Banksia | encyclopedia = Flora Australiensis | volume = Volume 5: Myoporineae to Proteaceae | pages = 541–562 | location = London | publisher = L. Reeve & Co.]

In 1981, Alex George published a revision arrangement that placed "B. prionotes" in "B." subg. "Banksia" because of its flower spike, "B." sect. "Banksia" because its styles are straight rather than hooked, and "B." ser. "Crocinae", a new series of consisting of four closely related species, all with bright orange perianths and pistils.

George's arrangement remained current until 1996, when Kevin Thiele and Pauline Ladiges published an arrangement informed by a cladistic analysis of morphological characteristics. Their arrangement maintained "B. prionotes" in "B." subg. "Banksia", but discarded George's sections and his series "Crocinae". Instead, "B. prionotes" was placed at the end of "B." ser. "Banksia", subser. "Cratistylis".cite journal | author = Thiele, Kevin and Pauline Y. Ladiges | year = 1996 | title = A Cladistic Analysis of Banksia (Proteaceae) | journal = Australian Systematic Botany | volume = 9 | issue = 5 | pages = 661–733 | doi = 10.1071/SB9960661]

In 1999, George overturned Thiele and Ladiges' arrangement, publishing a slightly modified version of his 1981 arrangement in his treatment of "Banksia" for the "Flora of Australia" series of monographs. To date, this remains the most recent, and therefore current, arrangement. The placement of "B. prionotes" in this arrangement may be summarised as follows::Genus "Banksia"::Subgenus "Isostylis"::Subgenus "Banksia":::Section "Oncostylis":::Section "Coccinea":::Section "Banksia"::::Series "Grandes"::::Series "Banksia"::::Series "Crocinae":::::"B. prionotes" - "B. burdettii" - "B. hookeriana" - "B. victoriae"::::Series "Prostratae"::::Series "Cyrtostylis"::::Series "Tetragonae"::::Series "Bauerinae"::::Series "Quercinae"::::Series "Salicinae"

Since 1998, Austin Mast has been publishing results of ongoing cladistic analyses of DNA sequence data for the subtribe Banksiinae, which is comprised of "Banksia" and "Dryandra". With respect to "B. prionotes", Mast's results are fairly consistent with those of both George and Thiele and Ladiges. Series "Crocinae" appears to be monophyletic, and "B. hookeriana" is confirmed as "B. prionotes"' closest relative. Overall, however, the inferred phylogeny is very greatly different from George's arrangement, and provides compelling evidence for the paraphyly of "Banksia" with respect to "Dryandra".cite journal | author = Mast, A. R. | year = 1998 | title = Molecular systematics of subtribe Banksiinae ("Banksia" and "Dryandra"; Proteaceae) based on cpDNA and nrDNA sequence data: implications for taxonomy and biogeography | journal = Australian Systematic Botany | volume = 11 | pages = 321–342 | doi = 10.1071/SB97026] cite journal | author = Mast, Austin and Thomas J. Givnish | year = 2002 | title = Historical biogeography and the origin of stomatal distributions in "Banksia" and "Dryandra" (Proteaceae) based on Their cpDNA phylogeny | journal = American Journal of Botany | volume = 89 | issue = 8 | pages = 1311–1323 | id = ISSN|0002-9122 | url = http://www.amjbot.org/cgi/content/full/89/8/1311 | accessdate=2006-07-02 | doi = 10.3732/ajb.89.8.1311] cite journal | author = Mast, Austin R., Eric H. Jones and Shawn P. Havery | year = 2005 | volume = 18 | issue = 1 | title = An assessment of old and new DNA sequence evidence for the paraphyly of "Banksia" with respect to "Dryandra" (Proteaceae) | journal = Australian Systematic Botany | pages = 75–88 | publisher = CSIRO Publishing / Australian Systematic Botany Society | doi = 10.1071/SB04015] Early in 2007, Mast and Thiele initiated a rearrangement of "Banksia" by transferring "Dryandra" into it, and publishing "B." subg. "Spathulatae" for the species having spoon-shaped cotyledons; in this way they also redefined the autonym "B." subg. "Banksia". 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. prionotes" is placed in "B." subg. "Banksia".cite journal | author = Mast, Austin R. and Kevin Thiele | year = 2007 | title = The transfer of "Dryandra" R.Br. to "Banksia" L.f. (Proteaceae) | journal = Australian Systematic Botany | volume = 20 | pages = 63–71 | doi = 10.1071/SB06016]

Hybrids

A number of presumed natural hybrids have been identified. Hybrids with "Banksia hookeriana" (Hooker's Banksia) may be induced by artificial means,cite journal | title = Interspecific hybridization between Banksia hookeriana Meisn. and Banksia prionotes Lindl. (Proteaceae) | first = Margaret | last = Sedgely | co-authors = M. G. Wirthensohn and K. L. Delaporte | journal = International Journal of Plant Sciences | volume = 157 | issue = 5 | pages = 638–643 | doi = 10.1086/297385 | year = 1996] and occur naturally on occasion; in fact the registered cultivar "B." 'Waite Orange' is known to have arisen from a natural hybrid of this parentage.cite journal | title = Interspecific hybridization involving Banksia prionotes Lind. and B. menziesii R.Br. (Proteaceae) | first = Margaret | last = Sedgley | co-authors = M. G. Sierp and T. L. Maguire | year = 1994 | journal = International Journal of Plant Sciences | volume = 155 | issue = 6 | pages = 755–762 | doi = 10.1086/297215] The same situation applies to hybrids with "B. menziesii" (Firewood Banksia): hybrids may be produced by artificial means, and presumed natural hybrids have been recorded.

During data collection for "The Banksia Atlas" project, a single presumed natural hybrid between "B. prionotes" and "B. lindleyana" (Porcupine Banksia), with fruit like "B. lindleyana" but leaves intermediate between the two parents, was found north of Kalbarri National Park. At the time this was considered an important discovery, as the parent species were thought to be not closely related.The Banksia Atlas] Mast's analyses, however, place them in a clade of eight species.

Distribution and habitat

It is widespread and locally common through much of the Southwest Botanical Province, occurring from Shark Bay (25°30′S) in the north, south as far as Perth (31.6 ° S) in coastal areas. Inland population extend further still, with populations as far south as Kojonup (33°50′S) and as far east as Jerramungup (34°24′S 118°55′E). It grows amongst tall shrubland or low woodland, and shows a very strong preference for deep white or yellow sand, virtually never being found in heavier soils.FloraBase | name = "Banksia prionotes" Lindl. | id = 1842]

Ecology

Like most other Proteaceae, "B. prionotes" has proteoid roots, roots with dense clusters of short lateral rootlets that form a mat in the soil just below the leaf litter. These enhance solubilisation of nutrients, allowing nutrient uptake in low-nutrient soils such as the phosphorus-deficient native soils of Australia. It also has a single tap root that extends down to the water table. As the species has neither thick bark nor a lignotuber, it is usually killed by fire, although it may resprout from epicormic buds following a low intensity fire. Like most "Banksia" species, however, it is adapted to release its aerial bank of seeds following a bushfire, so populations regenerate rapidly. Plants senesce if still alive after about 40 years, but this does not mean that the plant is dependent on a suitable fire regime for survival, as it is one of the few "Banksia" species that is not entirely serotinous: some of its follicles release seed spontaneously, allowing recruitment of seedlings in non-fire years.cite paper | title = Landscape Planning for Biodiversity Conservation in Agricultural Regions: A Case Study from the Wheatbelt of Western Australia | version = Biodiversity Technical Paper No. 2 | first = Robert J. | last = Lambeck | publisher = CSIRO Division of Wildlife and Ecology | year = 1999]

The main pollinators of "B. prionotes" are honeyeaters, including the New Holland Honeyeater, Brown Honeyeater, Singing Honeyeater, White-cheeked Honeyeater, Tawny-crowned Honeyeater and Red Wattlebird. The pollination relationship between these birds and "B. prionotes" has been well studied.cite journal | first = Brian G. | last = Collins | co-authors = John Spice | year = 1986 | title = Honeyeaters and the pollination biology of Banksia prionotes (Proteaceae) | journal = Australian Journal of Botany | volume = 34 | pages = 175–185 | doi = 10.1071/BT9860175] Other recorded pollinators include lories and lorikeets and bees. Pollination by mammals has not been recorded, and it has been suggested that this species may require pollination by birds in order to set seed.

Surveys of putative hydrids of "B. prionotes" with "B. hookeriana" have shown that these occur almost exclusively in areas that have been disturbed by humans, such as on road verges. In 2003, a study by Byron Lamont "et al." showed that these disturbed areas offered plants more resources and less competition. This allowed for prolonged flowering seasons, resulting in an overlap in flowering season which would not otherwise occur. It also allowed for greater overall flower production, resulting in more pollen and the presence of more pollinators. Thus the gene flow between the plants was greatly increased, and hybridisation resulted.cite journal | first = Byron | last = Lamont | authorlink = Byron Lamont | co-authors = T. He, N. J. Enright, S. L. Krauss and B. P. Miller | year = 2003 | title = Anthropogenic disturbance promotes hybridization betweenBanksia species by altering their biology | journal = Journal of Evolutionary Biology | volume = 16 | issue = 4 | pages = 551–557 | doi = 10.1046/j.1420-9101.2003.00548.x]

Conservation

"B. prionotes" is susceptible to a number of threatening processes. It is highly susceptible to "Phytophthora cinnamomi" dieback,cite journal | first = T. A. | last = McCredie | co-authors = K. W. Dixon and K. Sivasithamparam | year = 1985 | title = Variability in the resistance of Banksia L.f. species to Phytophthora cinnamomi Rands | journal = Australian Journal of Botany | volume = 33 | issue = 6 | pages = 629–637 | doi = 10.1071/BT9850629] cite web | url = http://www.environment.gov.au/biodiversity/invasive/publications/p-cinnamomi/pubs/appendix4.pdf | title = Part 2, Appendix 4: The responses of native Australian plant species to "Phytophthora cinnamomi" | work = [http://www.environment.gov.au/biodiversity/invasive/publications/p-cinnamomi/ Management of Phytophthora cinnamomi for Biodiversity Conservation in Australia] | publisher = Department of the Environment and Heritage, Australian Government | year = 2006 | accessdate = 2007-04-30] it is exploited commercially by the cut flower industry, and some of its range is subject to land clearing for urban or agricultural purposes. It is not considered particularly vulnerable to these factors, however, as it is so widely distributed and common. Western Australia's Department of Environment and Conservation do not consider it to be rare, and have not included it on their Declared Rare and Priority Flora List.

It nonetheless has high conservation importance in at least one context: it has been shown than "B. prionotes" is the only source of nectar in the Avon Wheatbelt region during a critical period of the year when no other nectar-producing plant is in flower, meaning that the loss of "B. prionotes" from the region would mean the loss of all the honey-eaters as well.cite journal | title = Conserving Biological Diversity through Ecosystem Resilience | first = Brian | last = Walker | journal = Conservation Biology | volume = 9 | issue = 4 | year = 1995 | pages = 747–752 | doi = 10.1046/j.1523-1739.1995.09040747.x]

Cultivation

Described as "an outstanding ornamental species", its brightly coloured, conspicuous flower spikes make "B. prionotes" a popular garden plant. It is good for attracting honey-eaters to the garden, and sometimes flowers twice a year. It is fairly easy to grow in areas with a Mediterranean climate, but does not do well in areas with high summer humidity. It requires a sunny position in well-drained soil, and tolerates at least moderate frost. It should be pruned lightly, not below the green foliage, as it tends to become straggly with age otherwise. Seed is easily germinated.

The species is also considered ideal for cut flower production, as its flowers fulfill the commercial criteria of terminal blooms and a long stem length.cite book | title = Native Australian plants: horticulture and uses | editor = Krystyna A. Johnson and Margaret Burchett | publisher = University of New South Wales Press | year = 1996 | location = Sydney | first = Margaret | last = Sedgley | chapter = Banksia, Family Proteaceae]

References

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