In 1981,
Alex George published a thorough revision of
Banksia in his classic monograph
The genus Banksia L.f. (Proteaceae). He retained the name
Orthostylis, but demoted it to series rank, placing it in
B. subg. Banksia because of its elongate "flower spike", and in
B. sect. Banksia, because it has straight styles after
anthesis. 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. The result was a series of just eight species, all of which had been included in Bentham's
B. sect.
Orthostylis. The other eleven members of Bentham's
Orthostylis were moved into other sections and series. The placement and circumscription of
B. ser.
Orthostylis in George's 1981 arrangement may be summarised as follows: :
Banksia ::'
B.
subg. Banksia
' :::'
B.
sect. Banksia
' ::::
B. ser. Salicinae (9 species) ::::
B. ser. Grandes (2 species) ::::
B. ser. Quercinae (3 species) ::::'''
B. ser.
Orthostylis''' :::::
B. serrata :::::
B. aemula :::::
B. ornata :::::
B. menziesii :::::
B. speciosa :::::
B. baxteri :::::
B. candolleana :::::
B. sceptrum ::::
B. ser. Crocinae (4 species) ::::
B. ser. Cyrtostylis (12 species) ::::
B. ser. Prostratae (6 species) ::::
B. ser. Tetragonae (3 species) ::::
B. ser. Coccineae (1 species) :::
B. sect. Oncostylis (3 series, 21 species) ::
B. subg. Isostylis (2 species) 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".
B. aemula (wallum banksia) was also flagged as anomalous in having a conical
pollen-presenter, and
B. pilostylis (marsh banksia) was noted as the only species outside the series that has a hairy pistil. Overall, George accepted that the resultant series was "somewhat heterogeneous", but argued that the species had enough in common to warrant grouping them together. Since species of
B. ser.
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. ==According to Thiele and Ladiges==