Interspecific and intergeneric pollen-tube growth was investigated using
controlled hand pollinations of Banksia coccinea R.Br.,
35 species of Banksia L.f., and three species of the
related genus Dryandra R.Br. Currently, the relationship
between B. coccinea and other species groups within
Banksia is unclear. Some species supported no
germination of B. coccinea pollen, some supported normal
pollen-tube growth and others produced pollen-tube abnormalities including
thickened walls, bulbous swellings, directionless growth, burst tips and
branched tubes. Control of pollen-tube growth in the pistil was imposed in the
pollen presenter and upper style. There was no significant reciprocal effect
on pollination success in the lower style. The results of pollen-tube
compatability in the lower style indicated that
B. coccinea has a closer affinity to the section
Oncostylis, than the section
Banksia where it is currently placed. Intergeneric
crosses of B. coccinea with
Dryandra species resulted in some compatibility, with
one cross having low numbers of pollen-tubes in the pollen presenter and upper
style region. These results indicate a close relationship between
Banksia and Dryandra, which are
sister genera in the tribe Banksiae, family Proteaceae.