[Taxacom] Dispersal... again

[Karl Magnacca]

On Tue, 25 Oct 2011 Dick Jensen wrote:
> I recall, from years ago, hearing a report
> of a plant species (I don't recall what it was) that was known to
> occur in two places in the world - Australia (where it was
> common)?and Cook County, Illinois (where it was quite rare).? The
> only logical explanation was long-distance dispersal.? How else?

A similar example would be the genus Shortia, which consists of four
species found in Japan, China, and Taiwan, and one in the southern
Appalachians (the Acony bell of Gillian Welch's song).  However,
that one almost certainly is the result of range contraction and
extinction of the intermediates in the distribution.

On the other hand, in addition to Fragaria chiloensis, from Hawaii
we also have Myoporum sandwicense (found in Hawaii and Mangareva in
the Cook islands), Pisonia brunoniana (Hawaii, Norfolk, Lord Howe,
Kermadec Islands, as well as NZ and Oz), Uncinia brevicaulis
(Hawaii, Juan Fernandez Islands, Tristan da Cunha, and mainland
South America), and Uncinia unciniata (Hawaii and NZ).  That's just
off the top of my head, I know there are many more examples.  It's
easy to see how those could be readily transported by birds -
Pisonia has sticky fruits, while Uncinia has hooked seeds that
easily catch on feathers.

Karl