I was thinking about geums and they seem like an unusual plant in that they look like weeds; hairy and arguably ugly plants. Indeed one of the most recent threads on this forum talks about geum urbanum and how the OP was advised to get rid of it.
And then you have plants like Geum Totally Tangerine and Blazing Sunset that seem to be quite popular (indeed I bought both during the winter). I'm sure there is no exact answer to this, but as a newbie gardener I'm wondering what is the dividing line that makes some geums worth £6, and sought after, for a small plant but others are seen as pure weeds.
In the case of geums, the wild one is rather invasive and has insignificant flowers. The cultivated variety has attractive flowers and has required a lot of effort and money to be developed.