later B. oligantha. Banksia ilicifolia is the only common member of that subgenus; the two other species are rare and threatened, 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, a 2004 study of genetic divergence within the subgenus yielded both other possibilities: some analyses suggested B. ilicifolia as basal, while others suggested B. oligantha. Biogeographical factors suggest that B. ilicifolia would be the most basal of the three species: it occurs in the High Rainfall Zone where relictual species are most common, whereas the others are restricted to the Transitional Rainfall Zone, where more recently evolved species are most common. 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. The placement of B. ilicifolia was unchanged in George's 1999 arrangement, and can be summarised as follows: Banksia B. subg. Banksia (3 sections, 11 series, 73 species, 11 subspecies, 14 varieties) B. subg. Isostylis B. ilicifolia B. oligantha B. cuneata 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. Their analyses suggest a phylogeny that differs greatly from George's taxonomic arrangement. Banksia ilicifolia and B. oligantha form a clade, that is they are each other's closest relative, with Banksia cuneata resolving as the next closest relative, suggesting a monophyletic B. subg. Isostylis; but the clade appears fairly derived (that it, it evolved relatively recently), suggesting that B. subg. Isostylis may not merit subgeneric rank. 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. Distribution and habitat A relatively common species, the holly-leaved banksia is widely distributed within south west Western Australia. It occurs within of the