The fruiting structure is a stout woody "cone", with a hairy appearance caused by the persistence of old withered flower parts. Up to 70 woody follicles, each of which contains a single seed, may be embedded in the cone. As with other "Banksia" species, only a small proportion of flowers go on to form follicles; in the case of "B. telmatiaea", the proportion is around 4% for those "cones" that set some fruit. About 80% of fruiting structures set no fruit at all. According to John K. Scott, "there no obvious reason on the basis of morphology of pollination for this lack of seed set".