Banksia epica
| Banksia epica | |
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| Species: | B. epica
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| Banksia epica | |
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 south east of the state, near the western edge of the Great Australian Bight. Both populations occur amongst coastal heath on cliff-top dunes of siliceous sand.
One of the most recently described Banksia species, it was probably seen by Edward John Eyre in 1841, but was not collected until 1973, and was only recognised as a distinct species in 1988. There has been very little research on the species since then, so knowledge of its ecology and cultivation potential is limited. It is placed in Banksia ser. Cyrtostylis, alongside its close relative, the well-known and widely cultivated B. media (Southern Plains Banksia).
Description
B. epica grows as a spreading bushy shrub with many branches, from 30 centimetres to 3½ metres (1–11½ ft) tall. It has grey, fissured bark, and dark green, wedge-shaped leaves, 1½ to 5 centimetres (½–2 in) long and 6 to 15 millimetres (1⁄8–2⁄3 in) wide, with serrated margins.
Flowers occur in Banksia's characteristic "flower spike", an inflorescence made up of hundreds of pairs of flowers densely packed in a spiral round a woody axis. B. epica's flower spike is yellow or cream-yellow in colour, cylindrical, 9 to 17 centimetres (3½–6½ inches) tall and around 6 centimetres (2½ inches) in diameter. In bud, it may have green-grey or brownish pollen presenters, not unlike B. robur (Swamp Banksia).[1] Each flower consists of a tubular perianth made up of four fused tepals, and one long wiry style. Characteristic of its taxonomic section, the styles of B. epica are straight rather than hooked. The style ends are initially trapped inside the upper perianth parts, but break free at anthesis. The fruiting structure is a stout woody "cone" embedded with up to 50 follicles; old withered flower parts persist on the "cones", giving them a hairy appearance.[2] The follicles have an attractive purple hue.
B. epica is similar in appearance to its close relative B. media, from which it differs in having slightly shorter leaves and larger flowers. In addition, the persistent flower parts on B. epica's fruiting structures are curled and point upwards, whereas they are straight and point downwards on B. media.[3]
Taxonomy
Taxonomic history
The first European to see B. epica was probably Edward John Eyre,[4] the first explorer of the area, who recorded "stunted specimens" of Banksia as he was nearing the western edge of the Great Australian Bight on 1 May 1841:
"One circumstance in our route to-day cheered me greatly, and led me shortly to expect some important and decisive change in the character and formation of the country. It was the appearance for the first time of the Banksia, a shrub which I had never before found to the westward of Spencer's Gulf, but which I knew to abound in the vicinity of King George's Sound, and that description of country generally. Those only who have looked out with the eagerness and anxiety of a person in my situation, to note any change in the vegetation or physical appearance of a country, can appreciate the degree of satisfaction with which I recognised and welcomed the first appearance of the Banksia. Isolated as it was amidst the scrub, and insignificant as the stunted specimens were that I first met with, they led to an inference that I could not be mistaken in, and added, in a tenfold degree, to the interest and expectation with which every mile of our route had now become invested."[5]
Eyre is thought to have been passing through the Toolinna Cove sand patch at the time of writing.[6] B. epica and B. media are the only Banksia species that occur at that location,[2] and both have a form and habit that accords with Eyre's description. As he did not collect specimens, it is impossible to determine what species he saw.
The first herbarium collection of B. epica was not made until October 1973, when Ernest Charles Nelson visited Toolinna Cove to collect specimens for a taxonomic revision of Adenanthos. He became interested in the disjunct plant distributions there, and ended up collecting specimens of a range of plant species.[6] On 22 October, he collected a specimen of B. epica in old flower, but incorrectly identified it as B. media, and later lodged it in the herbarium at Canberra under that name.[4]
In 1985, two volunteer field collectors for The Banksia Atlas project, John and Lalage Falconer of Esperance, discovered there were three Banksia species rather than two at Point Culver. Returning to the locality on 9 January 1986, they collected leaves and old flowers of what they thought was an undescribed species. The specimens did indeed suggest that a new species had been discovered, but they were not sufficient for formal publication. Early in May the following year, John Falconer drove over 2000 kilometres on unsealed tracks from Warburton to Point Culver and back again, in order to collect fresh flowers and fruit of the purported new species.[3] Alex George then began preparing a formal description of the species. During his research, he discovered that Nelson's Toolinna Cove specimen was also referrable to the undescribed species. In the absence of any genuine B. media specimens from Toolinna Cova, George inferred that only B. epica occurred there, and that Eyre must have sighted B. epica in 1841. In 1988, he published a formal description of the species, naming it Banksia epica in reference to the two "epic" journeys of Eyre and Falconer.[4] Thus the species' full name is Banksia epica A.S.George.[7] It was later established that both B. epica and B. media occur at Toolinna Cove.[2]
Current treatment
B. epica is placed in Banksia subg. Banksia, because its inflorescences take the form of Banksia's characteristic flower spikes; Banksia sect. Banksia because of its straight styles; and Banksia ser. Cyrtostylis because it has slender flowers. Its closest relatives are B. praemorsa (Cut-leaf Banksia) and B. media, both of which have shorter flowers and smaller pollen-presenters than B. epica. In addition, B. praemorsa differs in having a hairless perianth, and B. media has larger, more undulate leaves.[4]
In 1996, a cladistic analysis of Banksia by Kevin Thiele and Pauline Ladiges confirmed B. epica's placement in Cyrtostylis alongside B. praemorsa and B. media, despite finding George's conception of Cyrtostylis to be "widely polyphyletic". Thiele and Ladiges' arrangement removed ten Cyrtostylis species to other series, retaining only B. epica, B. media, B. praemorsa and B. pilostylis (Marsh Banksia).[8] These changes were not accepted by George, however, and were discarded in his 1999 revision.[2]
B. epica's placement within Banksia may be summarised as follows:
- Genus Banksia
- Subgenus Banksia
- Section Banksia
- Series Salicinae
- Series Grandes
- Series Banksia
- Series Crocinae
- Series Prostratae
- Series Cyrtostylis
- B. media - B. praemorsa - B. epica - B. pilostylis - B. attenuata - B. ashbyi - B. benthamiana - B. audax - B. lullfitzii - B. elderiana - B. rosserae -B. laevigata - B. elegans - B. lindleyana
- Series Tetragonae
- Series Bauerinae
- Series Quercinae
- Section Coccinea
- Section Oncostylis
- Section Banksia
- Subgenus Isostylis
- Subgenus Banksia
Distribution and habitat
B. epica is known only from two populations in eastern parts of the Esperance Plains region of the South West Botanical Province, near the western edge of the Great Australian Bight. The main population occurs about 30 kilometres (20 mi) west of Point Culver; there were over 2000 plants there when surveyed in June 1989. A smaller population occurs about 70 kilometres (45 mi) further east at Toolinna Cove; when surveyed in August 1991, this locality had around 350 plants. This latter population represents the easternmost limit of the western Banksia species; east of Toolinna Cove no Banksia species occurs for over 900 kilometres (550 mi).
In both localities, B. epica occurs amongst heath on cliff-top dunes of deep, white siliceous sand over limestone. It co-occurs with B. media in both localities, and B. praemorsa is also present at Point Culver. Toolinna Cove sand is somewhat alkaline, making B. epica and B. media the only Banksia species that grow in alkaline soil.[9]
These two localities are unusual in having cliff-top dunes of siliceous sand: cliff-top dunes are an unusual topographic formation, and nearly all soil in the area is calcareous. As Banksia species are intolerant of calcareous soils, and are not adapted to long range seed dispersal, the two populations of B. epica appear to be reproductively isolated. Nelson has suggested that there was once a continuous strip of siliceous sand along the coast, providing an extensive and unfragmented habitat for B. epica; rises in the sea level had submerged this strip, leaving only the cliff-top dunes as suitable habitat. The fact that the resultant isolated populations have not perceptibly speciated since then suggests that the species has been fragmented for only a short time, perhaps only since the Last Glacial Maximum.[6]
Ecology
Pollinators of B. epica include the New Holland Honeyeater and the Yellow-rumped Thornbill.[10] No other pollinators have been recorded, but the species is poorly surveyed, and studies of other Banksia species have consistently indicated a wide range of invertebrate and vertebrate pollinators. For example, a survey of the closely related and co-occurring B. media found that "honeyeater birds and marsupial nectarivores were abundant in the study area and most carried the pollen of Banksia media while it flowered.… Self-pollination and pollination by insects clearly also play major roles in seed production."[11]
Like most other Proteaceae, B. epica 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. The species lacks a lignotuber, so is thought to be killed by fire. Like most Banksia species, however, it is adapted to release its aerial bank of seeds following a bushfire, so populations regenerate rapidly. Since species closely related to B. epica all show low to medium susceptibility to Phytophthora cinnamomi dieback,[12] it is assumed to be similarly susceptible.[10]
Because so few populations are known, B. epica has been declared "Priority Two - Poorly Known Taxa" under the Department of Environment and Conservation's Conservation Codes for Western Australian Flora. It is not considered to be under threat, however, because both known populations occur within the Nuytsland Nature Reserve, and are undisturbed and healthy.[10] Furthermore, the area in which it occurs is poorly surveyed, so it is possible that other populations exist.[3]
Cultivation
B. epica is fairly new to cultivation. Kevin Collins of the Banksia Farm in Albany, Western Australia is said to have pioneered its cultivation, growing it in loamy clay or sandy gravel. It showed good tolerance for alkaline soils in those conditions, and has also succeeded in sandy, alkaline soil near the coast between Mandurah and Kwinana.[1] The Australian National Botanic Gardens in Canberra has also had some success in cultivating the species. Seeds were sown in February 1996, and planted out in November 1997; seedlings planted into sections without good drainage died, but two seedlings that were planted into a section with excellent drainage were about a metre tall by 2002, and flowering prolifically.[13][14]
In the absence of further information specific to B. epica, George recommends that cultivated plants be treated as for B. media and B. praemorsa, both of which require a sunny position in well drained soil, and tolerate only light pruning not below the green foliage.[15] Propagation is by seed or cuttings.[13]
References
- ^ a b Collins, Kevin (2002). "Banksia in horticulture". Australian Plants. 21 (173). ASGAP: 379–383. ISSN 0005-0008.
- ^ a b c d George, Alex S. (1999). "Banksia". In Wilson, Annette (ed.). Flora of Australia. Vol. Volume 17B: Proteaceae 3: Hakea to Dryandra. CSIRO Publishing / Australian Biological Resources Study. pp. 175–251. ISBN 0-643-06454-0.
{{cite encyclopedia}}:|volume=has extra text (help) - ^ a b c Taylor, Anne and Stephen D. Hopper (1988). The Banksia Atlas (Australian Flora and Fauna Series Number 8). Canberra: Australian Government Publishing Service. ISBN 0-644-07124-9.
- ^ a b c d George, Alex S. (1988). "New taxa and notes on Banksia L.f. (Proteaceae)". Nuytsia. 6 (3): 309–317.
- ^ Eyre, Edward John (1845). Journals of Expeditions of Discovery into Central Australia. London: T. and W. Boone. Retrieved 2007-02-16.
- ^ a b c E. Charles Nelson (1974). "Disjunct plant distributions on the south-western Nullarbor Plain, Western Australia". Journal of the Royal Society of Western Australia. 57 (4): 105–117.
- ^ "Banksia epica A.S.George". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.
- ^ Thiele, Kevin (1996). "A Cladistic Analysis of Banksia (Proteaceae)". Australian Systematic Botany. 9 (5): 661–733. doi:10.1071/SB9960661.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Lamont, Byron B. and S. W. Connell (1996). "Biogeography of Banksia in southwestern Australia". Journal of Biogeography. 23 (3): 295–309. doi:10.1046/j.1365-2699.1996.00027.x.
- ^ a b c Gillian F. Craig and Coates, David J. (2001). "B. Priority 2 Taxa". Declared Rare and Poorly Known Flora in the Esperance District. Bentley, Western Australia: Department of Conservation and Land Management. ISSN 0816-9713.
{{cite book}}:|access-date=requires|url=(help); External link in|chapterurl=|chapterurl=ignored (|chapter-url=suggested) (help) - ^ Wooller, S. J. and R. D. Wooller (2002). "Mixed mating in Banksia media". Australian Journal of Botany. 50: 627–631. doi:10.1071/BT01075.
- ^ McCredie, Thomas A., Kingsley W. Dixon and K. Sivathamparam (1985). "Variability in the Resistance of Banksia L.f. Species to Phytophthora cinnamomi Rands". Australian Journal of Botany. 33: 629–637. doi:10.1071/BT9850629.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b "Banksia epica". Association of Societies for Growing Australian Plants (ASGAP). Retrieved 2006-08-30.
- ^ Liber, C. (2002). "Banksia epica, media & praemorsa in ANBG, Canberra" (PDF). Banksia Study Group Newsletter. 4 (1). ASGAP: 4. ISSN 1444-285X. Retrieved 2006-12-15.
- ^ George, Alex S. (1984). The Banksia Book (Second Edition). Kenthurst, New South Wales: Kangaroo Press (in association with the Society for Growing Australian Plants). ISBN 0-86417-006-8.
External links
- Template:Flora of Western Australia
- "Banksia epica". Flora of Australia Online. Department of the Environment and Heritage, Australian Government.
- Banksia epica, Australian Plant Name Index (APNI)