Oliver wrote: > > >The whole thing is interesting, from two angles. One is 'how' and the other is >'why'. > >Taking the 'why' first, the presumed object of scent release is to attract >pollinators. If a plant releases a scent in the evening alone, one suspects >and evening visitor. However, if it smells thus during the dry afternoon and >so immediately after rain, is it attracting two separate pollinators: one that >is present in dry conditions and another which only flies when humidity is >high? If so, then this is a considerable evolutionary leap. Or perhaps normal, >quotidian pollinators get 'bored', and need the equivalent of sexy knickers to >raise their interest. In which case, why only after rain? > >In respect of the 'how', plainly the flower responds to higher turgor. The >speed with which it does so implies that it secretes or exposes pre-prepared >scents, rather than making them from scratch. I know of no record of organs >which do this in flowers of any species, but perhaps readers can correct my >ignorance. However, I wonder the could not be a chemical reaction between the >existing odorant and water which falls physically on the flower, rather than >being taken up by the roots. I will try the experiment as soon as we have a >warm day, but right now Britain is celebrating April with several inches of >snow. >______________________________ > >Oliver Sparrow
One thing I remember from botany/organic chemistry classes long ago was that certain fragrances are discerned differently at different concentrations. One of our professors said that the normally killer stink of the north american skunk (in it's very high concentration after the animal releases it) is actually a nice, floral-type fragrance when releases in much, much lower concentrations. Maybe with the orchid(s) it's a case that the scent released when wet is it's 'normal' intended fragrance when it's pumping out scent at high volumes, but when conditions aren't optimum and the speed at which scent release is possible is much 'slower' or lower and not having enough of the water component changes the perceived scent. Of course, a floral scent researcher would be able to tell if it is a case of different chemistry or different amounts of the same (which could have already been stated here and I have already forgotten -smile). regards, charles -- charles ufford oriskany, ny usa _______________________________________________ the OrchidGuide Digest (OGD) orchids@orchidguide.com http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
