Banksia sceptrum

Sceptre banksia
Banksia sceptrum chris email.jpg
Banksia sceptrum
Scientific classification
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B. sceptrum
Binomial name
Banksia sceptrum
Synonyms

Sirmuellera sceptrum (Meisn.) Kuntze

Banksia sceptrum, commonly known as the sceptre banksia, occurs in Western Australia near the central west coast from Geraldton north through Kalbarri to Hamelin Pool. It extends inland almost to Mullewa. First collected and grown by early settler James Drummond in Western Australia, it was described by Swiss botanist Carl Meissner in 1855.

In nature, it grows in deep yellow or pale red sand in tall shrubland, commonly on dunes, being found as a shrub to 5 metres (16 ft) high, though often smaller in exposed areas. It is killed by fire and regenerates by seed. Follicles open with fire. B. sceptrum is one of the most striking yellow-flowered banksias of all. Its tall bright yellow spikes, known as inflorescences, are terminal and well displayed. Flowering is in summer, mainly December and January, though occasional flowers are rarely seen at other times.

Description

Banksia sceptrum generally grows as a shrub to 2–4 m (6 12–13 ft) high,[1] though sometimes reaches 5 m (16 12 ft). It is many-branched and can reach 4 m (13 ft) in diameter. The stocky trunk has smooth or mildly tesselated pale grey bark.[2] New growth has been recorded in spring and autumn, and may possibly occur over the summer.[1] New branchlets are covered in fine greenish-brown fur and become smooth and pale grey after around two years.[2] The leaves are roughly oblong-shaped with truncate or emarginate ends and measure 4–9 cm (1 123 12 in) long and 1–3 cm (381 18 in) cm wide. They are on 5–8 mm (1438 in) long petioles. The flat leaf margins have short blunt teeth. The upper and lower surfaces of the leaf are covered in dense fur, but become smooth with age.[3]

The tall flower spikes, known as inflorescences, arise at the ends of vertical branches over November to January,[4] and can be striking in appearance. They take 6–7 months to develop—longer than other members of the genus.[2] Between 7 and 21 cm (3 and 8 12 in) high and 8–10 cm (3 14–4 in) cm wide, they are bright yellow and highly prominent. Anthesis takes place over 1–2 weeks,[2] and proceeds up the flower spike.[5] The ageing flowers turn grey and remain on the spikes as the oval follicles develop. The infructescences—old spikes bearing follicles—are bulky with a 6–8 cm (2 143 14 in) diameter. There are up to 50 follicles on each spike, each 1.5–2.5 cm (12–1 in) long, 0.8–1.8 cm (3834 in) high and 1–1.6 cm (1234 in) wide. When new they are covered with dense grey fur, which wears off exposed areas.[2]

The obovate (egg-shaped) seed is 3–3.5 cm (1 181 38 in) long and fairly flattened. It is composed of the obovate seed body (containing the embryonic plant), measuring 1.1–1.4 cm (3812 in) long by 0.7–0.9 cm (1438 in) wide, and a papery wing. One side, termed the outer surface, is brown and slightly wrinkled and the other is brown-black and sparkles slightly. The seeds are separated by a sturdy dark brown seed separator that is roughly the same shape as the seeds with a depression where the seed body sits adjacent to it in the follicle. Known as cotyledons, the first pair of leaves produced by seedlings are obovate and measure 1.4–1.5 cm (1258 in) long by 1.2 cm (12 in) wide. Their upper leaf margin of the wedge is crinkled. The auricle at the base of the cotyledon leaf is pointed and measures 0.2 cm (18 in) long. [2]

Taxonomy

Swiss botanist Carl Meissner described Banksia sceptrum in 1855, the type specimen having been collected by James Drummond north of the Hutt River sometime during 1850 or 1851. The species name sceptrum "sceptre" referring to the prominent flower spikes.[6] In his 1856 arrangement of the genus, there were 58 described Banksia species. Meissner divided Brown's Banksia verae, which had been renamed Eubanksia by Stephan Endlicher in 1847,[2] into four series based on leaf properties. He placed B. sceptrum in the series Quercinae.[7] George Bentham published a thorough revision of Banksia in his landmark publication Flora Australiensis in 1870. In Bentham's arrangement, the number of recognised Banksia species was reduced from 60 to 46. Bentham defined four sections based on leaf, style and pollen-presenter characters. Banksia sceptrum was placed in section Orthostylis.[8] In his 1891 work Revisio Generum Plantarum, German botanist Otto Kuntze challenged the generic name Banksia L.f., on the grounds that the name Banksia had previously been published in 1775 as Banksia J.R.Forst & G.Forst, referring to the genus now known as Pimelea. Kuntze proposed Sirmuellera as an alternative, republishing B. sceptrum as Sirmuellera sceptrum.[9] The challenge failed, and Banksia L.f. was formally conserved in 1940.[10][2]

In his 1981 monograph The genus Banksia L.f. (Proteaceae), Alex George placed B. sceptrum in B. subg. Banksia because its inflorescence is a typical Banksia flower spike shape; in B. sect. Banksia because of its straight styles; and B. ser. Banksia because of its robust inflorescence and hairy pistil that is prominently curved before anthesis. He added that its follicles resembled those of Banksia ornata, while the muricate seed body resembled those of B. speciosa and B. baxteri, though its obovate, crinkled cotyledons suggested an affinity with the series Cyrtostylis.[2]

Kevin Thiele and Pauline Ladiges published a new arrangement for the genus in 1996; their morphological cladistic analysis yielded a cladogram significantly different from George's arrangement. Thiele and Ladiges' arrangement retained B. sceptrum in series Banksia, placing it in B. subser. Cratistylis along with eight other Western Australian species. It was placed as an early offshoot within the group.[11] This arrangement stood until 1999, when George effectively reverted to his 1981 arrangement in his monograph for the Flora of Australia series.[3] B. spectrum's placement within Banksia according to Flora of Australia is as follows:

Growing as a gnarled shrub in exposed low shrubland in north of its range
Genus Banksia
Subgenus Banksia
Section Banksia
Series Banksia
B. serrata
B. aemula
B. ornata
B. baxteri
B. speciosa
B. menziesii
B. candolleana
B. sceptrum

In 2002, a molecular study by Austin Mast showed Banksia sceptrum and B. ashbyi to be each other's closest relatives, the two lying in a larger group made up of the members of the subseries Cratistylis plus Banksia lindleyana.[12] This was reinforced in a 2013 molecular study by Marcel Cardillo and colleagues using chloroplast DNA and combining it with earlier results.[13]

Mast, Eric Jones and Shawn Havery published the results of their cladistic analyses of DNA sequence data for Banksia in 2005. They inferred a phylogeny greatly different from the accepted taxonomic arrangement, including finding Banksia to be paraphyletic with respect to Dryandra.[14] A new taxonomic arrangement was not published at the time, but early in 2007 Mast and Thiele initiated a rearrangement by transferring Dryandra to Banksia, 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. sceptrum is placed in B. subg. Banksia.[15]

Distribution and habitat

In bud, used in cut flower industry

Banksia sceptrum is found from Hamelin Pool south to around 60 km (37 mi) east of Geraldton and near Mullewa and east to Wandana Nature Reserve.[1] The annual rainfall is 300–400 mm (12–16 in).[6] The soils it grows on are deep yellow or pale red sands, often on dunes.[3] It is also found on flat areas.[1] Found in tall shrubland,[3] it grows in association with B. ashbyi, mallee gums,[1] sandplain cypress (Actinostrobus arenarius) and sandplain woody pear (Xylomelum angustifolium).[16]

Ecology

Like many plants in Australia's southwest, Banksia sceptrum 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.[17] Banksia sceptrum is killed by bushfire and regenerates by seed,[1] the follicles on the old flower spikes remaining closed until burnt by fire. New plants take three to five years to flower again.[2] If bushfires are too frequent—occurring less than four years apart—they risk eradicating populations of reseeders locally.[17]

B. sceptrum has been shown to be highly susceptible to dieback from the soil-borne water mould Phytophthora cinnamomi, unlike many Western Australian banksias.[18]

An assessment of the potential impact of climate change on this species found that its range is unlikely to contract and may actually grow, depending on how effectively it migrates into newly habitable areas.[19]

Cultivation

B. sceptrum is principally used in the cut flower industry, with the immature spikes being commonly sold in florists around Australia. It is occasionally grown in gardens as its bright flower spikes are prominent, but requires a Mediterranean (dry summer) climate and good drainage as it is sensitive to dieback.[20] Seeds do not require any treatment, and take 26 to 47 days to germinate.[21] A dwarf form is in cultivation.[6]

References

  1. ^ a b c d e f Taylor, Anne; Hopper, Stephen (1988). The Banksia Atlas (Australian Flora and Fauna Series Number 8). Canberra: Australian Government Publishing Service. ISBN 0-644-07124-9. pp. 208–09.
  2. ^ a b c d e f g h i j George, Alex S. (1981). "The Genus Banksia L.f. (Proteaceae)". Nuytsia. 3 (3): 239–473 [335–37]. ISSN 0085-4417.
  3. ^ a b c d George, Alex S. (1999). "Banksia". In Wilson, Annette (ed.). Flora of Australia. Volume 17B: Proteaceae 3: Hakea to Dryandra. Collingwood, Victoria: CSIRO Publishing / Australian Biological Resources Study. pp. 175–251. ISBN 0-643-06454-0.
  4. ^ "Banksia sceptrum Meisn". FloraBase. Western Australian Government Department of Parks and Wildlife.
  5. ^ Elliot, Rodger W.; Jones, David L.; Blake, Trevor (1985). Encyclopaedia of Australian Plants Suitable for Cultivation: Vol. 2. Port Melbourne: Lothian Press. p. 302. ISBN 0-85091-143-5.
  6. ^ a b c Collins, Kevin; Collins, Kathy; George, Alex S. (2008). Banksias. Melbourne, Victoria: Bloomings Books. pp. 323–24. ISBN 1-876473-68-1.
  7. ^ Meissner, Carl (1856). "Proteaceae: Quercinae: B. coccinea". In de Candolle, A.P (ed.). Prodromus Systematis Naturalis Regni Vegetabilis, Pars Decima Quarta (in Latin). 14. Paris, France: Sumptibus Victoris Masson. p. 459.
  8. ^ Bentham, George (1870). "Banksia. Flora Australiensis: Volume 5: Myoporineae to Proteaceae. London, United Kingdom: L. Reeve & Co. pp. 541–62.
  9. ^ Kuntze, Otto (1891). Revisio Generum Plantarum. Leipzig, Germany: A. Felix. p. 582.
  10. ^ Sprague, Thomas Archibald (1940). "Taxonomic botany, with special reference to the angiosperms". In Huxley, Julian (ed.). The new systematics. Oxford, United Kingdom: The Clarendon Press. pp. 435–54.
  11. ^ Thiele, Kevin; Ladiges, Pauline Y. (1996). "A Cladistic Analysis of Banksia (Proteaceae)". Australian Systematic Botany. 9 (5): 661–733. doi:10.1071/SB9960661.
  12. ^ 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.
  13. ^ Cardillo, Marcel; Pratt, Renae (2013). "Evolution of a Hotspot Genus: Geographic Variation in Speciation and Extinction Rates in Banksia (Proteaceae)". BMC Evolutionary Biology. 13 (155). doi:10.1186/1471-2148-13-155. PMC 3751403. PMID 23957450.
  14. ^ Mast, Austin R.; Jones, Eric H.; Havery, Shawn P. (2005). "An Assessment of Old and New DNA Sequence Evidence for the Paraphyly of Banksia with Respect to Dryandra (Proteaceae)". Australian Systematic Botany. 18 (1): 75–88. doi:10.1071/SB04015.
  15. ^ Mast, Austin R.; Thiele, Kevin (2007). "The Transfer of Dryandra R.Br. to Banksia L.f. (Proteaceae)". Australian Systematic Botany. 20: 63–71. doi:10.1071/SB06016.
  16. ^ Grein, Shaun B. (1994). "Native Vegetation Handbook for the Shire of Mingenew". Perth, Western Australia: Department of Agriculture and Food, Western Australia. p. 4. Retrieved 31 May 2017.
  17. ^ a b Lamont, Byron B.; Markey, Adrienne (1995). "Biogeography of Fire-killed and Resprouting Banksia Species in South-western Australia". Australian Journal of Botany. 43 (3): 283–303. doi:10.1071/BT9950283.
  18. ^ McCredie, Thomas A.; Dixon, Kingsley W.; Sivasithamparam, Krishnapillai (1985). "Variability in the Resistance of Banksia L.f. Species to Phytophthora cinnamomi Rands". Australian Journal of Botany. 33 (6): 629–37. doi:10.1071/BT9850629.
  19. ^ Fitzpatrick, Matthew C.; Gove, Aaron D.; Sanders, Nathan J.; Dunn, Robert R. (2008). "Climate change, plant migration, and range collapse in a global biodiversity hotspot: the Banksia (Proteaceae) of Western Australia". Global Change Biology. 14 (6): 1–16. doi:10.1111/j.1365-2486.2008.01559.x.
  20. ^ Stewart, Angus (2016). "Banksia sceptrum". Gardening with Angus. Retrieved 31 May 2017.
  21. ^ Sweedman, Luke; Merritt, David (2006). Australian seeds: a guide to their collection, identification and biology. CSIRO Publishing. p. 203. ISBN 0-643-09298-6.

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