Banksia marginata ? seed pod
As the flower spikes or heads age, the flower parts dry up and may turn shades of orange, tan or dark brown colour, before fading to grey over a period of years. In some species, old flower parts are lost, revealing the axis; in others, the old flower parts may persist for many years, giving the fruiting structure a hairy appearance. Old flower spikes are commonly referred to as "cones", although they are not: cones only occur in conifers and cycads.
Despite the large number of flowers per inflorescence, only a few of them ever develop fruit, and in some species a flower spike will set no fruit at all. The fruit of Banksia is a woody follicle embedded in the axis of the inflorescence. These consist of two horizontal valves that tightly enclose the seeds. The follicle opens to release the seed by splitting along the suture, and in some species each valve splits too. In some species the follicles open as soon as the seed is mature, but in most species most follicles open only after stimulated to do so by bushfire. Each follicle usually contains one or two small seeds, each with a wedge-shaped papery wing that causes it to spin as it falls to the ground.
Source en.wikipedia.org/wiki/Banksia accessed 30 Jan 2010
Australia oz2009 695