Winter afternoon

A lovely way to spend a winter afternoon... the Zoo's conservatory. When it's really cold and dry and lifeless outside, it feels so good to just sit and relax in a warm humid environment full of plants. Just sit there and read a book, or think about things, or wander around curiously observing. Quiet on days like this, just an occasional visitor or zoo worker, very peaceful.

Guess what is the tallest plant in the conservatory? I estimate about 9 metres tall and about 3cm diameter at the base, quite impressive. (ok the description gives it away)