| from the July 21, 2008 Newsletter, after a visit to Land
Between the Lakes National Recreation Area in northwestern Tennessee: THE TRUMPET CREEPER'S TOUCH-SENSITIVE STIGMA LOBES Trumpet Creeper vines, CAMPSIS RADICANS were at their peak of flowering at Land Between the LakesI was able to photograph their touch-sensitive stigma lobes. That's a lakeside Trumpet Creeper above. Now look at close-ups of a flower's bi-lobed stigma (the female part atop the ovary's style, where male pollen lands and germinates) before and then ten seconds after I touched it, nestled among anthers, below:
Touch a stigma with its two flat lobes open, and you can actually see the lobes closing up. It's been assumed that the Trumpet Creeper's touch- sensitive stigmas help plants cross-pollinate instead of self-pollinate. A 2004 study in China, however, found that both pollen from another plant as well as a flower's own pollen caused the stigmas to close permanently. The researchers could only conclude that the stigma-closing behavior probably helps pollination somehow. |
