> >---end quote. One wonders how this actually happened: Protea branches bobbing >in the ocean, and rooting on a foreign strand? It works for so-adapted palms >and mangroves, but proteas? Or more likely, therefore, seeds ingested by a >wandering, migrating bird? Applied to orchids, however, one truly wonders... >Theoretically, an orchid seed could blow many tiems round the world before >settling. But if so, and gioven the vast number of seeds that are dispersed, >why is the worlkd not uniformly covered with them? Darwin's famous calculation >about what would happen if all of the seeds from an Orchis plant were to >germinate in ideal distribution: in the first generation, they would cover a >large field, in the second, the Isle of Wight, in the third, they would carpet >the whole planet. >______________________________ > >Oliver Sparrow
Hello Oliver, It's possible that they did cover larger or different areas but with many climate changes they just aren't found there now. I saw a public television program about migrating birds a few weeks ago, and with the numbers of birds that move large distance back and forth (including butterflies as well) It isn't that unlikely that tiny seeds could hitchhike to different continents within days, which is very much within the lifespan of an orchid seed. One thing to consider is that the climates found generally north or south of any particular area are likely to have very different climates seasonally and non-terrestrial orchids might have a tougher time of finding a spot with the same weather. Also tropical areas that are covered in plant life might make it very difficult to start up where all of the likely niches might already be taken up. Darwin's calculations are likely correct if they fall in perfect conditions for that plant (like a hillside full of trees covered with tissue culture agar that doesn't mold), and microclimates abound that are very different one from each other. regards, charles -- charles ufford oriskany, ny usa _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
