"Banksia" subg. "Isostylis" was first published by Robert Brown in his 1810 "Prodromus Florae Novae Hollandiae et Insulae Van Diemen"; thus its full name, with author citation, is "Banksia" subg. "Isostylis" R.Br. Brown's arrangement was the first infrageneric arrangement of "Banksia", making "B." subg. "Isostylis" "Banksia"s first infrageneric taxon. Brown erected "B." subg. "Isostylis" to contain "B. ilicifolia", which was then the only known "Banksia" with a dome-shaped inflorescence. He did not explicitly name a type species for the subgenus, but "B. ilicifolia" is treated as the type because it was the only member when the subgenus was published.