Sunday, July 6, 2014

Oenothera biennis (Evening Primrose)

 Oenothera biennis, one of many evening primroses, have been a nightly joy in my garden for several weeks, and are keeping up their nightly extravaganza. I can see from the number of buds formed at the top of the stalk that they plan to continue for some time to come.
 When the light begins to fade in the evening the chosen buds seem to rise in preparation for the nightly show. First a single petal begins to emerge from the once tightly wound bud, then the sepals snap back from the bud, releasing it to open in a swirl of petals that is fast enough to see and cause a gasp in any sentient being. The time required for any single bud to unfold may vary from a few seconds to a minute or two. The speed of the opening seems to be related to the humidity and the soil moisture. Sometimes the petals unfold all in one fluid motion; at other times, there will be a pause right before the final wide open display.
Hawksbill moths, yes the same that lay the eggs that will become tomato horn worms, begin visiting the flowers as soon as they unfurl. As soon as a flower is fully open, they arrive out of nowhere to probe the interior, taking nectar and pollinating the flowers to produce the prodigious amount of seed that will follow. Once I saw a hawksbill hover over a partial opened flower that had paused in its opening. It apparently was not moving fast enough for the moth, who decided to go ahead and get the nectar, ready or not. It was a rape of the flower.
 Some of the flowers open just as dark is setting in, but others wait till good dark. All the ones that will open that evening will have opened in about 30 minutes from the time the first one starts. Add to the flower drama, the moth escapades, the singing of cicadas, frogs, toads, katydids, and one bird calling in concern for Chuck's Widow, and it is a magical evening.

The plants reseed mightily and I usually cut the seed stalks off before they can all cast their seed, or I could grow little else. These plants, as the name indicates, take 2 years to make flowers (biennis), but they get a jump on the first year by starting the new year when the seed are cast. I acquired my first seed in North Carolina from a neighbor who called them Pennsylvania Poppers. They do seem to pop open suddenly. But not only to Pennsylvania are these plants native but to most of  North America. In fact they have spread worldwide to temperate and subtropical areas, carried by gardeners eager to share the magic.

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