Orthostylis consisted of those Banksia species with flat leaves with serrated margins, and rigid, erect styles that "give the cones after the flowers have opened a different aspect".

The series was given a rather stricter circumscription to that of Bentham: it was defined as containing only those species with a hairy pistil that is prominently curved before anthesis.

Orthostylis in George's 1981 arrangement may be summarised as follows: The placement of B. sceptrum (Sceptre Banksia) in this series was initially tentative, as George felt that "in some respects it also shows a relationship to the series Cyrtostylis".

Overall, George accepted that the resultant series was "somewhat heterogeneous", but argued that the species had enough in common to warrant grouping them together.

Orthostylis occur in both western and eastern Australia, George suggested that it had evolved early, and was widespread across southern Australia before aridification and marine incursion established the Nullarbor Plain as a barrier to genetic exchange.

[3] In 1996, Kevin Thiele and Pauline Ladiges undertook a cladistic analysis of morphological characters of Banksia, which yielded a phylogeny somewhat at odds with George's taxonomic arrangement.

Crocinae:[4] B. ornata B. serrata B. aemula B. candolleana B. sceptrum B. baxteri B. speciosa B. menziesii B. burdettii B. victoriae B. hookeriana B. prionotes On the basis of this clade, Thiele and Ladiges abandoned B. ser.

They then divided the series into two subseries, placing B. ornata (Desert Banksia), B. serrata and B. aemula in B. subser.

Banksia in Thiele and Ladiges' arrangement may be summarised as follows:[4] Thiele and Ladiges' arrangement remained current only until 1999, when George's treatment of the genus for the Flora of Australia series of monographs was published.

[3] Since 1998, Austin Mast has been publishing results of ongoing cladistic analyses of DNA sequence data for the subtribe Banksiinae.

[5][6][7] Early in 2007 Mast and Thiele initiated a rearrangement of Banksia by transferring Dryandra into it, and publishing B. subg.

Mast and Thiele have foreshadowed publishing a full arrangement once DNA sampling of Dryandra is complete.