When does it produce catkins? If its about now, Garrya elliptica would fit the bill - get the variety 'James Roof' it has the longest catkins of all. Better in the ground, but would tolerate a large container for a few years (2-5), though you'd need to prune it yearly once its bigger, probably.

thats what came to my mind by the description Bamboo. they are lovely plants arnt they.

Plantaholic and I have recently posted photos of this plant in flower

I agree it sounds like garrya Elliptica

http://www.rhs.org.uk/Media/Images/Plants/GarryaEllipticaJamesRoof2_L?width=510

Here are more links ... I hope they help ...

http://www.growsonyou.com/photo/slideshow/63423-my-love-affair-with-j-r/member/terratoonie

http://www.growsonyou.com/photo/slideshow/134006-at-last-the-sky-is-blue-more-pics-in-blog-spring-time-in-my-gardens/member/terratoonie

http://www.growsonyou.com/photo/slideshow/56365-happy-2009-from-my-garrya-elliptica-james-roof/member/terratoonie

The wonderful silk tassle tree! Can be easily pruned to remain as a bush too. Cut down after flowering. Any good nursery should have some, especially now as they are flowering. Depending on the size of bush/tree you want a large container should be okay. For a 2m bush/tree I would use a 75l pot minimum, preferably more. Can you let it root out through the bottom of the pot?