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ROSE BLOSSOMS

Rose BlossomThe 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 at the right, that flower has many more than five petals. That's because the rose in the picture, and most of the roses you'll run across in average backyards, are horticultural varieties that have been hybridized and otherwise changed around by humans so that they have extra petals, which make them more gaudy.

In the 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.

structure of a rose blossomAt the left you see a cross-section of a rose blossom showing the parts better. Now it's clear that rose flowers are different from our Standard Blossom in other important ways, too.

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?

rose anther developing petal featuresIt 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!

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