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 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.

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

''Banksia epica'' grows as a spreading bushy shrub with many branches, from 30 centimetres to 3½ metres (1– ft) tall. It has grey, fissured bark, and dark green, wedge-shaped leaves, to 5 centimetres (–2 in) long and 6 to 15 millimetres (– 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 spirals, not unlike '' B. robur'' (swamp banksia). 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. The follicles have an attractive purple hue.

''Banksia 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''.

Taxonomy

Discovery and naming

The first European to see ''B. epica'' was probably Edward John Eyre, 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:

Eyre is thought to have been passing through the Toolinna Cove sand patch at the time of writing. ''B. epica'' and ''B. media'' are the only ''Banksia'' species that occur at that location, 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''. Nelson was stimulated to make that revision from an interest in the problem of disjunct plant distributions in southern Australia, and therefore collected specimens of a range of plant species. 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.

In 1985, two volunteer field collectors for ''The Banksia Atlas'' project, John and Lalage Falconer of Esperance, became convinced that 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, to collect fresh flowers and fruit of the purported new species. Alex George then began preparing a formal description of the species. During his research, he discovered that Nelson's Toolinna Cove specimen was also referable to the undescribed species. In the absence of any genuine ''B. media'' specimens from Toolinna Cove, 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. Thus the species' full name is ''Banksia epica'' A.S.George. It was later established that both ''B. epica'' and ''B. media'' occur at Toolinna Cove.

Infrageneric placement

George placed ''B. epica'' in ''B.'' subg. ''Banksia'', because its inflorescences are typical ''Banksia'' flower spikes; ''B.'' sect. ''Banksia'' because of its straight styles; and ''B.'' ser. ''Cyrtostylis'' because it has slender flowers. He considered its closest relatives to be '' 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.

In 1996, Kevin Thiele and Pauline Ladiges published the results of a cladistic analysis of morphological characters of ''Banksia''. They retained George's subgenera and many of his series, but discarded his sections. George's ''B.'' ser. ''Cyrtostylis'' was found to be "widely polyphyletic", as six of the fourteen taxa in that series occurred singly in locations throughout Thiele and Ladiges' cladogram. The remaining eight formed a clade that further resolved into two subclades, with ''B. epica'' appeared in one of them:

Thiele and Ladiges preferred to give series rank to the subclades, rather than the entire clade, so they transferred the taxa of the second clade into ''B.'' ser. ''Ochraceae'', retaining only the taxa of the first clade in ''B.'' ser. ''Cyrtostylis''. ''B. epica''s placement under Thiele and Ladiges' arrangement may be summarised as follows:
:''Banksia''
:: ''B.'' subg. ''Isostylis'' (3 species)
::'' B. elegans'' (''incertae sedis'')
:: ''B.'' subg. ''Banksia''
::: ''B.'' ser. ''Tetragonae'' (4 species)
::: ''B.'' ser. ''Lindleyanae'' (1 species)
::: ''B.'' ser. ''Banksia'' (2 subseries, 12 species)
:::'' B. baueri'' (''incertae sedis'')
:::'' B. lullfitzii'' (''incertae sedis'')
:::'' B. attenuata'' (''incertae sedis'')
:::'' B. ashbyi'' (''incertae sedis'')
:::'' B. coccinea'' (''incertae sedis'')
::: ''B.'' ser. ''Prostratae'' (8 species)
::: ''B.'' ser. ''Cyrtostylis''
::::'' B. pilostylis''
::::'' B. media''
::::''B. epica''
::::'' B. praemorsa''
::: ''B.'' ser. ''Ochraceae'' (3 species, 2 subspecies)
::: ''B.'' ser. ''Grandes'' (2 species)
::: ''B.'' ser. ''Salicinae'' (2 series, 11 species, 4 subspecies)
::: ''B.'' ser. ''Spicigerae'' (3 series, 7 species, 6 varieties)
::: ''B.'' ser. ''Quercinae'' (2 species)
::: ''B.'' ser. ''Dryandroideae'' (1 species)
::: ''B.'' ser. ''Abietinae'' (4 subseries, 15 species, 8 varieties)

The arrangement of Thiele and Ladiges was not accepted by George, and was discarded in his 1999 revision.
Under George's 1999 arrangement, ''B. epica''s placement was as follows:

:''Banksia''
:: ''B.'' subg. ''Banksia''
::: ''B.'' sect. ''Banksia''
:::: ''B.'' ser. ''Salicinae'' (11 species, 7 subspecies)
:::: ''B.'' ser. ''Grandes'' (2 species)
:::: ''B.'' ser. ''Banksia'' (8 species)
:::: ''B.'' ser. ''Crocinae'' (4 species)
:::: ''B.'' ser. ''Prostratae'' (6 species, 3 varieties)
:::: ''B.'' ser. ''Cyrtostylis''
:::::'' B. media''
:::::'' B. praemorsa''
:::::''B. epica''
:::::'' B. pilostylis''
:::::'' B. attenuata''
:::::'' B. ashbyi''
:::::'' B. benthamiana''
:::::'' B. audax''
:::::'' B. lullfitzii''
:::::'' B. elderiana''
:::::'' B. laevigata'' (2 subspecies)
:::::'' B. elegans''
:::::'' B. lindleyana''
:::: ''B.'' ser. ''Tetragonae'' (3 species)
:::: ''B.'' ser. ''Bauerinae'' (1 species)
:::: ''B.'' ser. ''Quercinae'' (2 species)
::: ''B.'' sect. ''Coccinea'' (1 species)
::: ''B.'' sect. ''Oncostylis'' (4 series, 22 species, 4 subspecies, 11 varieties)
:: ''B.'' subg. ''Isostylis'' (3 species)

Since 1998, Austin Mast has been publishing results of ongoing cladistic analyses of DNA sequence data for the subtribe Banksiinae. His analyses suggest a phylogeny that is rather different from previous taxonomic arrangements. With respect to ''B. epica'', however, Mast's results accord closely with the arrangement of Thiele and Ladiges, placing it in a polytomous clade corresponding exactly with Thiele and Ladiges' ''B.'' ser. ''Cyrtostylis''.

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. epica'' is placed in ''B.'' subg. ''Banksia''.

Distribution and habitat

''Banksia 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 among 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.

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.

Ecology

Pollinators of ''B. epica'' include '' Phylidonyris novaehollandiae'' (New Holland honeyeater) and '' Acanthiza chrysorrhoa'' (yellow-rumped thornbill). 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."

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 seed bank following a bushfire, so populations regenerate rapidly. It is highly susceptible to ''Phytophthora cinnamomi'' dieback.

Because so few populations are known, ''B. epica'' has been listed on the Department of Environment and Conservation's Declared Rare and Priority Flora List as "Priority Two – Poorly Known Taxa""; and as 2RC under the ROTAP system (rare but not currently endangered or vulnerable, and having a range less than 100 km). It is not considered to be under threat, however, because both known populations occur within the Nuytsland Nature Reserve, and are undisturbed and healthy. Furthermore, the area in which it occurs is poorly surveyed, so it is possible that other populations exist.

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. 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.

Propagation is by seed or cuttings. Seeds do not require any treatment, and take 14 to 49 days to germinate. 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.

References

External links

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{{DEFAULTSORT:Banksia epica
epica
Eudicots of Western Australia
Plants described in 1988