I have just returned from over a week working at DESY (das Deutsches Elektronen Synchrotron) at Hamburg, and when I am not so tired I hope to write up some more synchrotron stuff for you all.  We were working over the Easter holiday, and while the DESY Bistro provided a magnificent brunch over that four-day period, on Sunday and Monday the only place within walking distance where we could find something to eat in the evening was Burger King (very appropriate for Hamburg, don’t you think?)
In the meantime, here are two plants which I saw there, both of which were new to me.  The first is the Cornelian Cherry, Cornus mas, of which the English Wikipedia article says:
The wood of C. mas is extremely dense, and unlike the wood of most other woody plant species, sinks in water. This density makes it valuable for crafting into tool handles, parts for machines, etc. Cornus mas was used from the seventh century B.C. onward by Greek craftsman to construct spears, javelins and bows, the craftsmen considering it far superior to any other wood.
The German Wikipedia article is much longer and more informative, and tell us, among other things, that the spring flowers of this plant are very useful for bees, and that its fruit is used for making liquor in Austria and further east.

I saw these shrubs/small trees growing both on the DESY campus and outside.  Pictures of this lovely plant growing in Canada can be seen here.  Alas, people tend to plant the more garish Forsythia, but the Cornus is, I think, much more wildlife-friendly.
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There is another plant which was new to me, and even more spectacular, which I saw in many gardens in the region surrounding DESY.  I do not have a copyright-free picture, but you can look at it in this article, and tell me if you know what it is.  I have not seen this plant outside Germany.
Saalfelder Ostereierbaum

(16 May 2013: from Wikimedia Commons, a magnificent specimen of this tree, in Saalfeld, quite close to the Czech Republic.  Thumbnail links to high resolution version)