By Emjamobr
United Kingdom 
Hello. I bought 2 small plants from a garden Centre 2 years ago thinking they were 2 different varieties of clematis (not sure which now). They have never flowered and the large one which is deciduous grows very quickly in the summer- I have to cut back every 2 weeks. I really don't think either are clematis and would love to know what I'm fact they are. Can anyone help please?!!
The first 2 photos are of the fast growing plant and the 3rd is of the slower growing plant (which hasn't actually ever done much!)
24 May, 2015
Answers
The last one could be a cotoneaster of some sort. Perhaps the reason it hasn't done much is that it wants to be a large shrub and it hasn't got enough root room. Although the pot's quite big it's only half full of compost. Put it in a bigger pot or in the ground. If its standing on soil you may even find its has rooted through the drainage hole into the ground.
24 May, 2015
The second plant, in the last photo, appears to be a Cotoneaster variety - I'm not surprised its not doing much, its not got enough soil around its roots to do much. It's hard to say whether its Cotoneaster bullatus or Cotoneaster sternianus - both are reasonably large shrubs, should produce small flowers which the bees love, followed by bright red berries. Only not in that half filled pot, it won't...
I don't recognise the other plant, though it might be reasonable to assume its also a Cotoneaster of some variety, so maybe you bought two Cotoneasters - they're definitely not Clematis varieties.
24 May, 2015