But then of course African swallows are not migratory.
However, they could have been dragged overland by a killer rabbit. 
That’s the one I’ve seen outside my sister’s and girlfriend’s houses, the leaves seem a bit broader than I thought but I recognise the shape and what I assume are the seeds (the greyish bushy part underneath) are recognisable too.
Belfast is a mild part of the country, small as it is I can see the difference as I head westward to my parents house, the grey clouds gathering as I approach Tyrone
Here`s a photo of the famous Newport Beach coconut tree from last year.
It looks like its doing quite well.
Mangosteen: Take a look at this seedling, which has about the same amount of trunk:
http://www2.junglemusic.net/gallery/large/palms/cocos_nucifera_001_(young).gif
The Newport coconut has a very sparse crown, it’s also stunted, from what I hear from people who’ve had a good look at it.
Dont know about ireland but the Devon Cornwall palms are indeed Cordyline Australis, which I amm fairly certain actually come from New Zealand, although there are probably similar species in Australia
Of course Australis in this context just means southern continent and not the actual country of Australia. This dates from the belief of early explorers that there was a massive land mass called Terra Australis. To quote Wikipedia
*Terra Australis (more completely Terra Australis Incognita, “(the) unknown southern land”) was an imaginary continent, appearing on European maps from the fifteenth to the eighteenth century. *
Australis in this context just means southern. It’s got nothing to do with any continent or any mistaken belief that NZ and Australia were the same landmass. If the species were discovered tommorrow it would still probably be named C. australis, and rightly so since it is the species of cordyline with the furthest southern distribution, the majority being firmly tropical plants.
There are similarly numerous genera with ‘australis’ species or subspecies from the US and Europe, which nobody could have believed was part of any southern landmass. The epithet simply means that this is the southern representative of the group, although in many cases that was a bit premature and more southerly representatives have since been found.
Thanks for that clarification.
Here’s a random result from a Google image search on **Palms Ireland[/b:
http://www.saintmarys.edu/~finn7022/ireland/20020929/Wicklow_PalmTrees.jpg
-Those are typical of the ‘palms’ I’ve seen widely planted in parts of Ireland I’ve visited, but as I said, they’re not true palms, they’re Cordylines.
IIRC Ireland is the only place in the world where Tropical and Arctic plants grow naturally side-by-side.
Another reason to not believe the statement that launched the OP, that the palm trees date from past physical connection to Africa, is the effect of the Ice Ages. From this handy map we can see that pretty much all if Ireland was ice covered 20,000 years ago. The small area “not widely glaciated” would have been cold enough to kill off any palms.
In reading the text, it indicates that “…around 13,000 years ago, the first trees (hardy Junipers) began to grow.” This suggests there wern’t any palm trees. (They had to wait for the return of the swallows.) It would appear that the surrounding ice probably killed off most of the plant life, certainly anything very large.
I first learned about the Ice Age impact on Ireland from a Straight Dope thread on snakes in Ireland (or the lack thereof).
And what tropical plants are those?
These have to be species from the tropics, not relatives. Please list exact species.
I wouldn’t doubt that tropical and arctic species grow side by side in Ireland, many species of ‘tropical’ plants like bracken and nutgrass have an extremely broad distribution, as do many ‘arctic’ species like willows and blueberry. I have no doubt that there are ‘arctic’ species of willow growing next to ‘tropical’ bracken in Ireland. The real question is why Ireland would be considered unique in that regard.
Close to the Arctic, yet first stop for the Gulf Stream to dump tropical seeds.
My earlier statement is a half-remembered NPR documentary on Irish botany.
I agree. My point is, that unless Ireland has plants that grow within the tropics only (or primarily, but range into subtropical areas) but managed to wash ashore and grow in some anomalous microclimate on the beaches there, then you can’t really say that Ireland has tropical plants growing next to arctic plants.
An example of this is Dodonea viscosa, or Hopseed bush. It grows in Hawaii, which is in the tropics, but the plant is also found in Arizona, and New Zealand. I wouldn’t call it a tropical plant due to that.
As I’d said, just because tropical plant species of a specific genus are found in the tropics, that doesn’t mean all of the members are tropical. There are tropical Oaks and Maples, but that doesn’t mean maples or oaks are tropical either.
I agree. My point is, that unless Ireland has plants that grow within the tropics only (or primarily, but range into subtropical areas) but managed to wash ashore and grow in some anomalous microclimate on the beaches there, then you can’t really say that Ireland has tropical plants growing next to arctic plants.
An example of this is Dodonea viscosa, or Hopseed bush. It grows in Hawaii, which is in the tropics, but the plant is also found in Arizona, and New Zealand. I wouldn’t call it a tropical plant due to that.
As I’d said, just because tropical plant species of a specific genus are found in the tropics, that doesn’t mean all of the members are tropical. There are tropical Oaks and Maples, but that doesn’t mean maples or oaks are tropical either.