Earlier this summer (if you can call it that), I planted some
sunflower seeds from a packet I had had for some time, but had
forgotten all about.
About 5 or 6 germinated and grew to well over 2.5m tall, but no flower
at the top. Instead, what looks like a sort of a bud, except I can't
see any sign that it might at some point turn into an actual sunflower
head.
Am I wrong and will they flower, or are they just blind?
And if so, why is that?

TIA

Cat(h) (feeling awfully soggy)