| Swamp fox banksia | |
|---|---|
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Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Proteales |
| Family: | Proteaceae |
| Genus: | Banksia |
| Species: | B. telmatiaea |
| Binomial name | |
| Banksia telmatiaea | |
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| Distribution ofBanksia telmatiaea | |
Banksia telmatiaea, commonly known asswamp foxbanksia or rarelymarsh banksia, is a shrub that grows in marshes and swamps along the lower west coast of Australia. It grows as an upright bush up to 2 metres (6 feet 7 inches) tall, with narrow leaves and a pale brown flower spike, which can produce profuse quantities of nectar. First collected in the 1840s, it was not published as a separate species until 1981; as with several other similar species it was previously included inB. sphaerocarpa (fox banksia).
The shrub grows amongstscrubland in seasonally wet lowland areas of the coastal sandplain betweenBadgingarra andSerpentine inWestern Australia. A little studied species, not much is known of itsecology orconservation biology. Reports suggest that a variety of birds and small mammals pollinate it. Like many members of the seriesAbietinae, it has not been considered to have much horticultural potential and is rarely cultivated.
B. telmatiaea grows as an upright bush up to 2 m (6.6 ft) high. It has hairy stems andbranchlets, and straight, narrow leaves from1+1⁄2 to 3 cm (1⁄2 to1+1⁄4 in) long and about aone millimetre (1⁄16 in) wide.[1] The leaves have a green upper surface and white hairy undersurface. The new growth is pale brown, later turning green.[2]
Flowers occur in "flower spikes",inflorescences made up of hundreds of flower pairs densely packed around a woody axis. Arising from short lateral branchlets off stems older than four years of age, the inflorescence ofB. telmatiaea is roughly oval to cylindrical, with a height of 3–5 cm (1–2 in) and diameter of4–7 centimetres (1+1⁄2–2+3⁄4 in).[2] It contains between 500 and 900 golden brown to pale brown flowers,[3] each of which consists of a tubularperianth made up of four fusedtepals, and one long wirystyle. The styles are hooked rather than straight, and are initially trapped inside the upper perianth parts, but break free atanthesis. The species generally flowers from April to August, although flowers have been observed as late as November.[4] They take five to six weeks to develop from bud, then reach anthesis over a period of two weeks. The flowers produce unusually large quantities ofnectar; indeed some flowers produce so much that it drips to the ground.[3]
The fruiting structure is a stout woody "cone", with a hairy appearance caused by the persistence of old withered flower parts.[1] Up to 70 woodyfollicles, each of which contains a single seed, may be embedded in the cone. As with otherBanksia species, only a small proportion of flowers go on to form follicles; in the case ofB. telmatiaea, the proportion is around 4% for those "cones" that set some fruit. About 80% of fruiting structures set no fruit at all. According toJohn K. Scott, "there [is] no obvious reason on the basis of morphology of pollination for this lack of seed set".[3]
B. telmatiaea was first collected around 1840 byLudwig Preiss andJames Drummond. For many years it was included inB. sphaerocarpa, but by 1980 it was recognised as a distinct species. In recognition of its distinctness from, yet affinity with,B. sphaerocarpa, it was for a time informally referred to asBanksia aff.Sphaerocarpa.[5] It was eventually published byAlex George in his 1981 monographThe genus Banksia L.f. (Proteaceae), based on a specimen collected by him on theBrand Highway about 45 kilometres (28 miles) north ofRegans Ford on 14 May 1969, and labelled "A. S. George 9309". He found it most closely resembledB. leptophylla, but regarded its preference for swampy rather than sandy soils and winter flowering as worthy of warranting species status.[2] George gave it the specific nametelmatiaea from theGreekstemtelmat-/τελματ- ("the mud of a pond"),[6] in reference to its swampy habitat.[2] Thus the full name for the species isBanksia telmatiaea A.S.George.[7] Common names forB. telmatiaea include swamp fox banksia and marsh banksia.[8]
George placedB. telmatiaea in subgenusBanksia because its inflorescence is a typicalBanksia flower spike, sectionOncostylis because it has hooked styles, and seriesAbietinae because its inflorescence is roughly spherical. He considered its closest relative to beB. leptophylla (Slender-leaved Banksia), which differs fromB. telmatiaea in having longer leaves and larger flowers; yet in his arrangement he placed it betweenB. scabrella (Burma Road Banksia) andB. laricina (Rose-fruited Banksia).[2]
In 1996,Kevin Thiele andPauline Ladiges published the results of acladistic analysis ofmorphological characters ofBanksia. They retained George's subgenera and many of his series, but discarded his sections.B. ser.Abietinae was found to be very nearlymonophyletic, and so retained. It further resolved into four subclades, so Thiele and Ladiges split it into foursubseries.B. telmatiaea appeared in the third of these:[9]
This clade became the basis ofB. subser.Leptophyllae, which Thiele defined as containing those species with "indurated and spinescent common bracts on the infructescence axes, and densely arachnose seedling stems." In accordance with their cladogram, their arrangement placedB. telmatiaea next toB. scabrella.[9]
Thiele and Ladiges' arrangement was not accepted by George, and was largely discarded by him inhis 1999 arrangement.B. ser.Abietinae was restored to George's 1981 circumscription, and all of Thiele and Ladiges' subseries were abandoned.B. telmatiaea was moved in thephyletic order to betweenB. grossa (Coarse Banksia) andB. leptophylla, thus better according with the affinity withB. leptophylla claimed by George in 1981.[1]
The placement ofB. telmatiaea in George's 1999 arrangement may be summarised as follows:[1]
Since 1998,Austin Mast has been publishing results of ongoing cladistic analyses ofDNA sequence data for the subtribeBanksiinae. His analyses suggest a phylogeny that is very different from George's arrangement. With respect toB. telmatiaea, Mast's results accord closely with Thiele and Ladiges' arrangement, inferring apolytomous clade consisting ofB. leptophylla,B. telmatiaea,B. scabrella andB. lanata, withB. grossa (Coarse Banksia) as the nearestoutgroup:[10][11][12]
Early in 2007, Mast and Thiele initiated a rearrangement ofBanksia by mergingDryandra into it, and publishingB. subg.Spathulatae for the taxa having spoon-shapedcotyledons. They foreshadowed publishing a full arrangement once DNA sampling ofDryandra was complete; in the meantime, if Mast and Thiele's nomenclatural changes are taken as an interim arrangement, thenB. telmatiaea is placed inB. subg.Spathulatae.[13]
B. telmatiaea grows only in theSwan Coastal Plain,Geraldton Sandplains andJarrah Forestbiogeographic regions, inland from the coast but never east of theDarling Scarp. It occurs fromHill River nearBadgingarra in the north, toSerpentine in the south. Most populations occur north ofMoore River or south ofCannington, there being only a few scattered populations in between.[4]
The species favours lowland areas that are seasonally wet but never inundated, such as the margins ofswamps andmarshes. For example, in theYule Brook Botany Reserve, where parallel sandridges cross a clay flat,B. telmatiaea occurs neither in the lowest parts of the flat, where seasonal inundation occurs; nor on the tops of the ridges, where the drainage is good; but it is one of the most abundant plants of intermediate habitats, on ridge slopes and in higher areas of the clay flat.[14]
Favoured soils are deep grey sandy loams or shallower sand overlyingclaypan. Associated vegetation is typicallyscrubland orshrubland, although moisture-loving trees such asB. littoralis (swamp banksia) orMelaleuca preissiana (moonah) may also be present, sometimes in sufficient numbers to form a low openwoodland.[4][15]
Like most otherProteaceae,B. telmatiaea hasproteoid roots, roots with dense clusters of short lateral rootlets that form a mat in the soil just below the leaf litter. These roots are particularly efficient at absorbing nutrients from nutrient-poor soils, such as thephosphorus-deficient native soils ofAustralia.[16]
Unlike manyBanksia species,B. telmatiaea lacks alignotuber, so plants are killed by bushfire. It is adapted to release itsaerial seed bank following a bushfire, and so regenerates rapidly.[17] This behaviour, known asserotiny, makesB. telmatiaea dependent upon a suitable fire regime for successful regeneration; indeed, excessive fire frequency may be one reason whyB. telmatiaea does not occur further south, despite suitable habitat throughoutsouthwest Australia.[18] Unlike most serotinousBanksia species, the seeds ofB. telmatiaea are not released immediately after the passage of a bushfire. The follicles open straight away, but at first the seeds are blocked from falling out by the wingedseed separator. If moistened, these wings close up, and as they dry they open out again, levering the seeds out of position, making it possible for them to fall. This adaptation ensures that seeds are released only after the first rains following a bushfire.[19]
Four species of bird have been observed visiting the flowers ofB. telmatiaea: thered wattlebird (Anthochaera carunculata),[4]silvereye (Zosterops lateralis),New Holland honeyeater (Phylidonyris novaehollandiae) and thebrown honeyeater (Lichmera indistincta). The introduced European honeybee (Apis mellifera) is also commonly observed, and visits byants andHylaeus plasterer bees have been recorded. Visits bynectarivorousmammals have not been directly observed, but their involvement in pollination is certain, as theirscats have often been found on inflorescences,[20] and studies of otherBanksia species have consistently demonstrated their involvement.[21] Moreover, a number of characteristics of theB. telmatiaea spike are purported to be adaptations to pollination by nocturnal mammals: the strong, musky odour,[20] the occurrence of inflorescences hidden within the foliage close to the ground, the large amounts of nectar produced, and the pattern of nectar production, which peaks at dawn and dusk. This last adaptation is thought to favour visits by birds and mammals, which feed in the morning and evening respectively, as opposed toinsects, which are most active during the day.[15]
Reproductive success is strongly affected by insects that infest the flower spikes and fruiting structures. Infestation of the flower spikes is not as severe as in otherBanksia species: one study found less than 10% ofB. telmatiaea inflorescences to be infested, compared to over 50% forB. attenuata (candlestick banksia),B. littoralis andB. menziesii (Menzies' banksia), and over 90% forB. grandis (bull banksia). Also, whereas other species were attacked by a range of insects, the inflorescence ofB. telmatiaea was attacked only by thetortrixmothArotrophora arcuatalis (banksia boring moth), which burrows into the woody axis, rendering the spike barren. On the other hand, the same study observed heavy infestation of fruiting structures, with over 90% of spikes with follicles found to contain at least one larva of an unidentified species of moth of the genusXylorycta. These larvae burrow from follicle to follicle to eat the seed, resulting in 100% seed loss for infested spikes.[3]
B. telmatiaea is one of fiveBanksia species, all closely related toB. sphaerocarpa, that have highly unusual flowernectar.[a] Whereas otherBanksia species produce nectar that is clear and watery, the nectar of these species is pale yellow initially, but gradually becomes darker and thicker, changing to a thick, olive-green mucilage within one to two days of secretion.[22] In the case ofB. telmatiaea, it eventually becomes "an almost black, gelatinous lump adhering to the base of the flowers".[5] This unusual nectar was first noted in 1980 byByron Lamont, who attributed its transformation to thecyanobacteria that he observed feeding off the nectarsugars. Noting that many of these cyanobacteria hadheterocysts, he speculated that they aid the plant byfixing atmospheric nitrogen, which is then washed off the flower heads by rain, and absorbed by the proteoid root mat. This purportedsymbiosis was investigated in 1985, but no evidence of nitrogen fixing was found.[23] Further investigations in 1996 suggested that the discolouration is not caused by cyanobacteria or other microorganisms in the nectar, but is rather "a chemical phenomenon of plant origin".[22] As of February 2007, the cause was still unknown.[20] Chemical analysis ofB. telmatiaea nectar has shown it to have a normal nectar sugar composition,[24] albeit dominated bysucrose.[20]
B. telmatiaea is a fairly secure species, as most populations are of more than 100 plants, and 26% of known plants are in conservation reserves. Its proximity toPerth suggests that land clearing for urban development could pose a threat, and in 1988The Banksia Atlas recommended that "the species should continue to be monitored since land clearing could change the situation greatly, particularly amongst its northern populations." It is also known to be susceptible to dieback caused by theintroduced plantpathogenPhytophthora cinnamomi, a soil-bornewater mould that causes root rot;[25] in fact it is so reliably susceptible that it is used as an indicator species for the presence of the disease.[26] An assessment of the potentialimpact of climate change on this species found that severe change is likely to lead toextinction; but under less severe change scenarios the distribution may actually grow, depending on how effectively it can migrate into newly habitable areas.[27]
In 1987, George applied the Rare or Threatened Australian Plants (ROTAP) criteria to the species, determining it to have a conservation status of "3R": a rare species found only in small populations, but not considered endangered or vulnerable.[17] Western Australia'sDepartment of Parks and Wildlife do not consider it to be rare, and have not included it on theirDeclared Rare and Priority Flora List.[28]
B. telmatiaea is rarely cultivated. It grows fairly quickly, but tends to become untidy as it ages. The flower spikes, though attractive, occur within the bush where they are usually obscured by foliage. In its natural habitat it flowers prolifically over several months, but according to George it may be reluctant to flower in cultivation. It tolerates light pruning not below the green foliage. George recommends a sunny position in poorly drained soil, preferably with moisture in winter.[17] Seeds do not require any treatment, and take around 14 days togerminate.[29]
