The blossoms of wild, native roses are similar to our Standard Blossom in that they possess five colorful petals. However, as you can see in the rose blossom pictured above, that rose has many more than five petals. That's because the rose in the picture, as are most of the roses you'll run across in average backyards, is a horticultural varieties that has been hybridized and otherwise changed around by humans so that it produces extra petals, which makes it more colorful.
In the above picture, the small, round, yellowish spot is several stigmas. Surrounding this cluster of stigmas are several mealy looking stamens, which consist of anthers atop their stemlike filaments. Then surrounding the stamens are the blossom's many bright petals. Below, you can get a better idea how the parts fit together:
For one thing, instead of possessing a single ovary, rose flowers have several. Each ovary's style joins with other styles and extends in a column upward through the surrounding stamens, and ends with its own stigma.
Even more profoundly different from our Standard Blossom is the fact that the ovaries are positioned on the side of a cuplike structure known as the hypanthium. The upper rim of the hypanthium more or less closes over the ovaries inside it, leaving only a hole large enough for the styles to pass through.
Atop the hypanthium there's a circular disk from which many stamens arise. Our Standard Blossom had only 5 stamens, so this is yet another difference between it and the average rose flower.
You might ask, How did horticulturists get wild, 5-petaled rose flowers to produce so many extra petals, and therefore make the flower more spectacular?
It happens that the genetic information that produces stamens is closely associated with that which produces petals. The proof of that is that sometimes in rose flowers you can find a stamen with certain features of a petal, or a petal with certain features of a stamen. As I was dissecting the above blossom I happened to find just such a thing, which is shown at the right. There you see a cluster of stamens removed from the staminal disk, with one of the stamens' anthers clearly becoming "petaloid" on one side. In this same blossom I also found petals with what appeared to be remnants of stamen filaments along their edges!