With strap-shaped flowers: some Asteraceae have tubular (regular) flowers in the center of the head, and strap-shaped flowers (ray flowers) along the margin....

...such as the daisies, where the strap-shaped flowers are white..:

... several other species whose flowers are all yellow...

...or some species of Achillea, where the flowers are all white:


Without strap-shaped flowers: in this case the flowers are all regular (tubular)...

We can distinguish at least 2 types of tubular flowers: in some cases they are very short, such as in Artemisia and in some species of Senecio..:

...in other cases the flowers have a long tube and long lobes, such as those of thistles:


In some genera, such as Centaurea, the marginal tubular flowers are much longer than the central ones and tend to radiate all aound the head: they should not be confused with strap-shaped flowers.