Banksia violacea

Species of plant

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. 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. 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. 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'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.

[[Image:Banksia violacea map. png|thumb|right|Distribution of B. violacea, shown on a map of Western Australia's 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. 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. 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. Seeds do not require any treatment, and take 19 to 50 days to germinate.