These florets are called disk florets because they form the central disk of the capitulum in typical daisies. The disk florets are usually surrounded by an outer ring of ray florets. These have bilaterally symmetric tubular corollas. The best known weedy composite, the common dandelion, has a third kind of floret, a ligulate floret. These resemble ray florets in having a bilaterally symmetric corolla, but ligulate florets are bisexual and have five apical teeth at the end of the strap.
Thistles have yet another kind of floret, bilabiate florets.
Like ligulate florets, bilabiate florets are usually bisexual. Although some of these distinctions may seem rather picky when you are first learning to identify members of the Asteraceae, it is important to realize that bilabiate, ray, and ligulate florets are not identical when one is trying to understand relationships within the family, or place a plant that one has never seen before. One way to help keep them straight is to redraw them in order from most primitive to most advanced. Apart from their differences in corolla shape and sexuality, the four types of floret are very similar. The ovary is inferior and encloses a single seed.