 = Banksia violacea = 
 
 Banksia violacea , commonly known as violet banksia , is a species of shrub or tree in the plant genus Banksia ( family Proteaceae ) . It generally grows as a small shrub to 1 @.@ 5 m ( 5 ft ) high with fine narrow leaves , and is best known for its unusually coloured dark purple @-@ violet inflorescences . The colour of the inflorescences , short leaves , and flattened follicles which are sticky when young , help identify this species from others in the field . It is found in low shrubland in southern regions of Western Australia from Esperance in the east to Narrogin in the west , growing exclusively in sandy soils . 
 First described in 1927 by the West Australian botanist Charles Gardner , the species was at one stage considered a variety of B. sphaerocarpa . Although there are no recognised subspecies or varieties , both lignotuberous and nonlignotuberous forms exist for Banksia violacea . Wasps , ants and flies have been recorded visiting flower spikes . Banksia violacea is classified as Not Threatened under the Wildlife Conservation Act of Western Australia . Regarded as of little value to floriculture , it is rarely cultivated . 
 
 = = Description = = 
 
 Banksia violacea grows as a shrub up to 1 @.@ 5 m ( 5 ft ) tall , with narrow leaves 1 – 2 cm ( 0 @.@ 4 – 0 @.@ 8 in ) long and about 0 @.@ 15 cm ( 0 @.@ 06 in ) wide . New growth occurs in summer , and flowering ranges from November to April with a peak in February , but can be irregular in timing . Flowers arise from typical Banksia " flower spikes " , and the inflorescences are made up of hundreds of pairs of flowers densely packed in a spiral around a woody axis . Roughly spherical with a diameter of 2 – 3 cm ( 0 @.@ 8 – 1 @.@ 2 in ) , the flower spikes arise from lateral stems lie partly within the foliage . Unusually for Banksia species , the inflorescences are often violet in colour , ranging anywhere from a dark violet @-@ black through various combinations of violet and greenish @-@ yellow in less pigmented blooms . Each flower consists of a tubular perianth made up of four fused tepals , and one long wiry style . The styles are hooked rather than straight , and are initially trapped inside the upper perianth parts , but break free at anthesis . The old flowers gradually fade to brown . The fruiting structure or follicle is a stout woody " cone " , with a hairy appearance caused by the persistence of old withered flower parts . These follicles are crowded around the globular spike ( called an infructescence at this point ) and are oval to rhomboid , although the crowding makes some irregularly shaped . They measure 1 – 2 @.@ 5 cm ( 0 @.@ 4 – 1 in ) long , 0 @.@ 6 cm ( 0 @.@ 2 in ) high and 0 @.@ 8 – 2 @.@ 2 cm ( 0 @.@ 3 – 0 @.@ 9 in ) wide . They are quite flattened and lack a ridge along the valve line . When young , the follicles are greenish in colour and slightly sticky , and covered in fine white hairs , fading to tan or grey with age . They open with fire , releasing a winged wedge @-@ shaped ( cuneate ) seed 2 – 2 @.@ 5 cm ( 0 @.@ 8 – 1 in ) long . The mottled dark grey seed body is falcate ( crescent @-@ shaped ) and measures 1 @.@ 2 – 1 @.@ 8 cm ( 0 @.@ 5 – 0 @.@ 7 in ) long and 0 @.@ 2 – 0 @.@ 25 cm ( 0 @.@ 1 in ) wide , with a flattened dark brown wing 1 @.@ 1 – 1 @.@ 7 cm ( 0 @.@ 4 – 0 @.@ 5 in ) wide . The woody separator has the same dimensions as the seed . 
 The bright green cotyledon leaves of the seedlings are oblong to linear in shape and measure 1 @.@ 5 cm ( 0 @.@ 6 in ) long by 0 @.@ 3 cm ( 0 @.@ 1 in ) wide . The greenish red hypocotyl is hairy , as are the stems of young plants . The hairy seedling leaves are crowded and oppositely arranged . They measure 0 @.@ 7 – 1 @.@ 3 cm ( 0 @.@ 2 – 0 @.@ 5 in ) in length and have recurved margins . Young plants often begin branching within their first year of life . 
 
 = = Taxonomy = = 
 
 The type specimen of Banksia violacea was collected by the West Australian botanist Charles Gardner on 14 December 1926 in the vicinity of Lake Grace . The following year , he published a description of the species in Journal and Proceedings of the Royal Society of Western Australia . He placed it in section Oncostylis of Bentham 's taxonomic arrangement of Banksia , giving it the specific epithet violacea in reference to the violet flowers . Thus the full name of the species , with author citation , is Banksia violacea C.A.Gardner. The species has been considered a variety of B. sphaerocarpa ( Fox Banksia ) ; this view was published by William Blackall in his 1954 How to know Western Australian wildflowers . He considered B. violacea to be a variety of B. sphaerocarpa with violet flowers . This description was an invalid publication , however , and a nomen nudum . In 1981 Alex George declared Banksia sphaerocarpa var. violacea Blackall a nomenclatural synonym of B. violacea . 
 In George 's 1981 arrangement , B. violacea was placed in subgenus Banksia because its inflorescence is a typical Banksia " flower spike " ; section Oncostylis because of its hooked styles ; and series Abietinae because its inflorescence is roughly spherical . It was placed in taxonomic sequence between B. incana ( Hoary Banksia ) and B. meisneri ( Meissner 's Banksia ) . 
 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 . B. ser . Abietinae was found to be very nearly monophyletic and so it was retained . It further resolved into four subclades , so Thiele and Ladiges split it into four subseries . B. violacea appeared in the last of these : 
 This clade became the basis of B. subseries Longistyles , which Thiele defined as containing those taxa with very long and slender styles , smoothly convex perianth limbs without a costal ridge , and thickened margins . In accordance with their cladogram , their arrangement placed B. violacea first in taxonomic sequence , followed by B. laricina ( Rose @-@ fruited Banksia ) . However , Thiele and Ladiges ' arrangement was not accepted by George , who , questioning the emphasis on cladistics , rejected most of their changes in his 1999 arrangement , restored B. series Abietinae to his broader 1981 definition , and abandoned all of Thiele and Ladiges ' subseries . George commented that the species has no close relatives , being " loosely allied " to B. sphaerocarpa ( Fox Banksia ) and B. telmatiaea ( Swamp Fox Banksia ) . Despite this , the sequence of the series was altered so that B. violacea fell between B. scabrella ( Burma Road Banksia ) and B. incana , and its placement in George 's arrangement may be summarised as follows : 
 Banksia 
 B. subg . Banksia 
 B. sect . Banksia ( 9 series , 50 species , 9 subspecies , 3 varieties ) 
 B. sect . Coccinea ( 1 species ) 
 B. sect . Oncostylis 
 B. ser . Spicigerae ( 7 species , 2 subspecies , 4 varieties ) 
 B. ser . Tricuspidae ( 1 species ) 
 B. ser . Dryandroideae ( 1 species ) 
 B. ser . Abietinae 
 B. sphaerocarpa ( 3 varieties ) 
 B. micrantha 
 B. grossa 
 B. telmatiaea 
 B. leptophylla ( 2 varieties ) 
 B. lanata 
 B. scabrella 
 B. violacea 
 B. incana 
 B. laricina 
 B. pulchella 
 B. meisneri ( 2 subspecies ) 
 B. nutans ( 2 varieties ) 
 B. subg . Isostylis ( 3 species ) 
 Since 1998 , an American botanist , 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 very greatly different from George 's arrangement , and somewhat different from Thiele and Ladiges ' . With respect to B. violacea , Mast 's results agree with its placement near B. laricina and B. incana , placing it in a clade with these two species and B. sphaerocarpa var. dolichostyla ( treated at species rank as B. dolichostyla ) . However , Thiele 's B. subseries Longistyles appears to be polyphyletic , as do both definitions of B. ser . Abietinae — that is , none form a natural grouping . 
 Early in 2007 , Mast and Thiele initiated a rearrangement of Banksia by merging Dryandra into it , and publishing B. subgenus Spathulatae for the taxa having spoon @-@ shaped cotyledons . 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. violacea is placed in B. subgenus Spathulatae . 
 
 = = Distribution and habitat = = 
 
 B. violacea occurs in southern regions of Western Australia , from Woodanilling to Esperance and as far north as Hyden . This distribution includes areas of the Avon Wheatbelt , Esperance Plains and Mallee biogeographic regions . It favours white sandy soils , often overlying laterite , clay or quartzite . It usually grows among heath and shrublands , associated with mallee eucalypts and Banksia sphaerocarpa var. caesia . Banksia violacea is classified as Not Threatened under the 1950 Wildlife Conservation Act of Western Australia . 
 
 = = Ecology = = 
 
 Like most other Proteaceae , Banksia violacea 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 , thus allowing their uptake in low @-@ nutrient soils such as the phosphorus @-@ deficient soils of Australia . B. violacea is highly susceptible to Phytophthora cinnamomi dieback . 
 Banksia violacea is one of a small number of Banksia species that has both lignotuberous and non @-@ lignotuberous populations . In both cases , plants are adapted to release their aerial seed bank following a bushfire , ensuring seedlings are established on clear and relatively fertile ground ; however the possession of a lignotuber makes plants much less reliant on fire regime for population maintenance and regeneration , as maternal plants are not killed by bushfire , but resprout from below ground level . Lignotuberous plants generally occur among the north @-@ eastern populations , in the vicinity of Woodanilling . An investigation into the biogeography of these plants failed to find any vegetative , climatic or other environmental factors associated with the possession of a lignotuber . 
 Banksia flowerheads in general play host to a variety of birds , mammals and insects . However , only wasps , ants and flies were recorded visiting flower spikes during observations for The Banksia Atlas in the mid @-@ 1980s . 
 
 = = Cultivation = = 
 
 Banksia violacea is rarely cultivated . It is a slow @-@ growing plant that tends to become untidy with age , and generally does not flower until four to five years after sprouting from seed . Flowers are an unusual colour , but occur within the bush where they grow within and are usually obscured by foliage . It tolerates light pruning not below the green foliage , except for the variant with a lignotuber , which may be pruned heavily . George recommends a sunny position in light , sandy soil . Professor Margaret Bernard Sedgley of the Waite Institute suggests the species is of no value to floriculture , as the inflorescences are too small and obscured by the foliage , although she does add that the purple colour may be a worthwhile character to select for in plant breeding . Seeds do not require any treatment , and take 19 to 50 days to germinate . 
 
 