Excerpts from Jim Conrad's
from the the April 6, 2009 Newsletter, issued from near Natchez, Mississippi:
BEFORE THE HEARTS BURST
Yet another very common plant -- a slender, lithe bush about shoulder high -- flowering now with very unusual and pretty blossoms you'd only notice if you were consciously walking around looking at things closely is that of the Hearts-a-bustin' or Strawberry Bush, EUONYMUS AMERICANUS. Its flower clusters curiously held almost flush with its paired, or opposite, leaves jutting out at right angles to the stem are shown above.
Its curious, greenish-yellow blossom is shown close-up below:
The five large, roundish, veined items are petals and the five much smaller, yellow things are pollen producing anthers atop very short filaments. The broad, smooth, round object occupying the flower's center is something fairly distinctive for the genus Euonymus. It's a disk attached to the calyx and completely covering the ovary lying hidden below the disk. In the disk's very center you see a very short stigma-bearing style poking through. Pollen from other flowers will germinate on the stigma and the male sex germ will migrate down through the style to the ovary below the disk. I'm guessing that the disk's function is simply to protect the delicate ovary.
None of this explains those names, "Heart-a-bustin'" and "Strawberry Bush." It's the fruits that people notice and inspire the name givers. In the fall the fruits turn red and warty like strawberries, then they BURST open releasing glossy, orange-red seeds. The fruits are very conspicuous and if you walk in eastern US forests where the species lives you'll probably recognize them in the fruit picture at http://www.wildflower.org/gallery/result.php?id_image=18943.