Банксия иллицифолия: описание и особенности

Tree in the family Proteaceae endemic to southwest Western Australia
Speciesbox
| name = Holly leaved banksia
| image = Banksia ilicifolia marchetti latebud2 email. jpg
| genus = Banksia
| parent = Banksia subg. Isostylis
| species = ilicifolia
| authority = R. Br. |synonyms ref = is a tree in the family Proteaceae. Endemic to southwest Western Australia, it belongs to Banksia subg. Isostylis, a subgenus of three closely related Banksia species with inflorescences that are dome shaped heads rather than characteristic Banksia flower spikes. It is generally a tree up to tall with a columnar or irregular habit. Both the scientific and common names arise from the similarity of its foliage to that of the English holly Ilex aquifolium; the glossy green leaves generally have very prickly serrated margins, although some plants lack toothed leaves. The inflorescences are initially yellow but become red tinged with maturity; this acts as a signal to alert birds that the flowers have opened and nectar is available. Robert Brown described Banksia ilicifolia in 1810. Although Banksia ilicifolia is variable in growth form, with low coastal shrubby forms on the south coast near Albany, there are no recognised varieties as such. Distributed broadly, the species is restricted to sandy soils. Unlike its close relatives which are killed by fire and repopulate from seed, Banksia ilicifolia regenerates after bushfire by regrowing from epicormic buds under its bark. It is rarely cultivated.

Banksia ilicifolia is a variable species. It usually grows as an erect tree up to in height, but some populations along the south coast consist of small trees or even spreading shrubs. It is generally a high small tree in the Margaret River region. The leaves arising from many short branchlets make a dense foliage close to the trunk and branches. Banksia ilicifolia has a stout trunk up to in diameter, and rough, fibrous, grey bark which is up to thick. The cotyledon leaves are a dull green with no visible nerves or markings. Transversely elliptic in shape, they measure 8 to 13 mm long by 12 to 18 mm wide and range from convex to concave. The pointed spreading auricles are 1.5 mm long. The cotyledon leaves sit atop the stout hypocotyl, which is green and smooth. The seedling leaves are crowded above the cotyledons. Resembling those of B. coccinea, they are lined with triangular lobes or "teeth" (with a u or v shaped sinus) and obovate to broadly lanceolate in shape. The first set of leaves measure in length and around in width, with three or four lobes in each margin. Both upper and lower seedling leaf surfaces are covered in spreading hairs, as is the seedling stem. Juvenile leaves are obovate to truncate or mucronate with triangular lobes and measure long by wide. These lobes are smaller toward the petiole and apex of the leaf. The species was also drawn by the expedition's botanical artist Ferdinand Bauer. Like nearly all of Bauer's field drawings of Proteaceae, the original field sketch of B. ilicifolia was destroyed in a Hofburg fire in 1945. A painting based on the drawing survives, however, at the Natural History Museum in London. Brown eventually published the species in his 1810 work On the natural order of plants called Proteaceae. The shrubby, coastal ecotype was published as a separate species Banksia aquifolium by John Lindley in his 1840 A Sketch of the Vegetation of the Swan River Colony, but this is now regarded as a taxonomic synonym of B. ilicifolia. This application of the principle of priority was largely ignored by Kuntze's contemporaries, and Banksia L. f. was formally conserved and Sirmuellera rejected in 1940.

The unranked group Isostylis, with its one species, was reclassified as a section in the 1856 arrangement of Carl Meissner, and 1870 arrangement of George Bentham. In his 1981 revision of the genus, Alex George reclassified the group as a subgenus—Banksia subg. Isostylis—defined by the dome shaped flower heads, with B. ilicifolia joined by newly described species B. cuneata and later B. oligantha. and are protected under the Environment Protection and Biodiversity Conservation Act 1999. Relationships between B. ilicifolia and the other members of B. subg. Isostylis still remain unclear. Although DNA studies found B. cuneata to be the most basal of the three species, The placement of B. ilicifolia was unchanged in George's 1999 arrangement, and can be summarised as follows: Early in 2007, Mast and Thiele rearranged the genus Banksia by merging Dryandra into it, and published B. subg. Spathulatae for the taxa having spoon shaped cotyledons; thus B. subg. Banksia was redefined as encompassing taxa lacking 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. ilicifolia is placed in B. subg. Banksia.

A relatively common species, the holly leaved banksia is widely distributed within south west Western Australia. It occurs within of the coast, from Mount Lesueur to Augusta, and then east to the Cordinup River east of Albany. In the Margaret River region, it grows on yellow sand plains behind the Leeuwin Naturaliste Ridge. Banksia ilicifolia grows exclusively on sandy soils; its range ends where heavy soils are evident. Banksia ilicifolia is a component of the critically endangered Assemblage of Tumulus Springs (organic mound springs) of the Swan Coastal Plain community north of Perth, which is characterised by a permanently moist peaty soil. The dominant trees include M. preissiana, swamp banksia (B. littoralis) and flooded gum (Eucalyptus rudis), with understorey ferns such as bracken (Pteridium esculentum) and Cyclosorus interruptus, and shrubs swamp peppermint (Taxandria linearifolia) and Astartea fascicularis.

Banksia ilicifolia has been recorded as a source of nectar for the honey possum (Tarsipes rostratus) in winter to early summer (May to December), from field studies in the Scott National Park, replaced by Adenanthos meisneri in the summer. Several honeyeater species visit and pollinate Banksia ilicifolia. The western spinebill (Acanthorhynchus superciliosus) in particular prefers this species over other banksias. A field study carried out at Jandakot Airport south of Perth and published in 1988 found that birds and insects overwhelmingly preferred visiting yellow coloured flowerheads. The species recorded include several species of honeyeater, including the red wattlebird (Anthochaera carunculata), western wattlebird (A. lunulata), western spinebill, brown honeyeater (Lichmera indistincta), New Holland honeyeater (Phylidonyris novaehollandiae), white cheeked honeyeater (P. nigra), singing honeyeater, (Lichenostomus virescens), as well as the twenty eight parrot (Barnardius zonarius semitorquatus)

An analysis of the invertebrate population in the canopy of Banksia woodland found that mites and ticks (Acari), beetles (Coleoptera) and ants, bees and wasps (Hymenoptera) predominated overall, with the three orders also common on B. ilicifolia, although outnumbered by thrips (Thysanoptera). More arthropods on B. ilicifolia might be related to a higher nutrient (potassium) level in the leaves. Lower overall numbers of invertebrates on Banksia species were thought to be related to the presence of insectivorous birds. Further experiments show that seedlings of outcrossing with plants greater than apart are more vigorous and adaptable, suggesting that plants breeding within small fragmented populations are subject to reduced vigour and genetic inbreeding. Banksia ilicifolia regenerates after bushfire by regrowing from epicormic shoots under its bark. Follicles open and release seeds after several years. The other two species of the subgenus Isostylis are killed by fire and regenerate by seed. The plant develops masses of fine lateral roots which form a mat like structure underneath the soil surface. These enable it to extract nutrients as efficiently possible out of the soil. A study of three co occurring species in Banksia woodland in southwestern Australia—Banksia menziesii, B. attenuata and B. ilicifolia—found that all three develop fresh roots in September after winter rainfall, and that the bacteria populations associated with the root systems of B. menziesii differ from the other two, and that they also change depending on the age of the roots. Along with its shallow lateral roots, Banksia ilicifolia sinks one or more deep taproots seeking the water table. It is an obligate phreatophyte, that is, it is reliant upon accessing groundwater for its survival; it is more closely tied to the water table than the co occurring B. menziesii and B. attenuata, and must remain in areas where the depth of the water table is less than below the surface. Recent falls of the water table on the Swan Coastal Plain from use of the Gnangara Mound aquifer for Perth's water supply combined with years of below average rainfall have seen the population and vigour or Banksia ilicifolia fall considerably (more so than other banksia species) since the mid 1960s. Like many Western Australian banksias, Banksia ilicifolia has been shown to be highly sensitive to dieback from the soil borne water mould Phytophthora cinnamomi. A study of Banksia attenuata woodland southeast of Perth across 16 years and following a wave of P. cinnamomi infestation showed that B. ilicifolia populations were present but significantly reduced in diseased areas. Specimens in coastal dune vegetation were reported killed by Armillaria luteobubalina, with mycelial sheaths of the fungus beneath the bark of the root collar.

Rarely cultivated, Banksia ilicifolia requires a sunny position and sandy well drained soil to do well. A slow growing plant, it takes up to ten years to flower from seed. The glossy green foliage and long flowering period, combined with prominently displayed flowers give it horticultural potential, although its prickly foliage makes fallen leaves a problem if planted near lawns or walkways. Difficulties in collection and low seed set make seed relatively expensive. Seeds are often eaten by insects before they can be collected.