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.

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.

Resembling those of holly, its leaves are a dark shiny green colour, and variously obovate (egg-shaped), elliptic, truncate or undulate (wavy) in shape, and 3–10 cm (1.2–3.9 in) long.

The inflorescences pass through three colour phases, being initially yellow, then pink, then finally red, before falling away from the head.

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.

[4] In 1810, Brown published Prodromus Florae Novae Hollandiae et Insulae Van Diemen in which he arranged the genus into two unranked groups.

[11] 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.

[3] A specimen collected by Ludwig Preiss on 13 April 1839 from coastal sands in Perth was described as Banksia ilicifolia var integrifolia in Bentham's Flora Australiensis in 1870,[12] but has not been recognised since.

[13] This application of the principle of priority was largely ignored by Kuntze's contemporaries,[14] and Banksia L.f. was formally conserved and Sirmuellera rejected in 1940.

[17] A 1996 cladistic analysis of the genus by botanists Kevin Thiele and Pauline Ladiges assumed the status B. subg.

Isostylis as a subgenus and earliest offshoot within Banksia, so George's placement of B. ilicifolia was retained in their arrangement.

[19] The placement of B. ilicifolia was unchanged in George's 1999 arrangement, and can be summarised as follows:[7] Since 1998, American botanist Austin Mast and co-authors have been publishing results of ongoing cladistic analyses of DNA sequence data for Banksia and Dryandra.

[22] A relatively common species, the holly-leaved banksia is widely distributed within southwest Western Australia.

[4] Almost all occurrences are to the west (seaward) side of the Darling Scarp, although there are two outlying populations – one near Collie east of Bunbury and the other in the Tonbridge-Lake Muir area near Manjimup.

The dominant trees include Melaleuca 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.

[28] 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.

[29] 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).

[5] Hand-pollination experiments on wild populations near Perth showed that Banksia ilicifolia is self-compatible, although progeny produced have less vigour and seed production is reduced.

[3] It is weakly serotinous, like eight other Banksia species, all of which tend to occur in Western Australia's southwestern corner.

[17] All banksias have developed proteoid or cluster roots in response to the nutrient-poor conditions of Australian soils (particularly lacking in phosphorus).

[33] The plant develops masses of fine lateral roots which form a mat-like structure underneath the soil surface.

[34] Along with its shallow lateral roots, Banksia ilicifolia sinks one or more deep taproots seeking the water table.

[36] 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 of Banksia ilicifolia fall considerably (more so than other banksia species) since the mid-1960s.

[38] A study of Banksia attenuata woodland 400 km (250 mi) 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.

[39] Specimens in coastal dune vegetation were reported killed by Armillaria luteobubalina, with mycelial sheaths of the fungus beneath the bark of the root collar.

[40] Rarely cultivated,[41] Banksia ilicifolia requires a sunny position and sandy well-drained soil to do well.