Excerpts from Jim Conrad's
from the February 23, 2009 Newsletter, issued from near Natchez, Mississippi:
Above you see a cluster of plum flowers arising from recently opened buds. At the upper right notice how the petals have fallen from one blossom leaving five triangular, green sepals. Do you see the slender, greenish, flat- topped item arising from the center of that flower? The flat platform atop the slender thing is the stigma and the slender thing itself is the style. The style arises atop the ovary down inside the shadowy, cuplike structure from which the sepals arise.
The green, cuplike thing below the triangular sepals is worth paying attention to. You can see how male stamens with their white filaments and yellow, pollen- producing anthers arise on the cup's outer rim, and how the ovary -- the future plum -- resides down in the cup's center. The flower's separate petals also arise from the cup's rim. This cup is something most flowers don't have, but it's very typical of the Rose Family, to which plums, genus PRUNUS, belong. Technically the cup is referred to as a hypanthium.
On the twigs, notice the white, flaky "skin" peeling off here and there, and see how some of the maroon- colored flower-bud scales are silvery at their bases. This paleness is called glaucescence and it's thought to protect a plant's tender parts from intense sunlight, causing some of it to reflect away.