I'll second the botanical gardens, just a bus ride away. There is a section devoted to Bonsai there, you really could get some interesting close up stuff of quite old trees.

Almost every day (it seemed) there was someone pruning very carefully and very slowly, a tree here and there.

Picnic lunch there is good it's a welcome rest from the hustle and bustle of the city and it's direct environs.

Mick.