I have a couple begonia "weeds" in my backyard. One is kinda nice with reddish stems and leaves while the other is boring...plain green leaves and small white flowers. Eventually I'd like to try and create a better weed. Basically I'd cross the weedy begonias with more showy begonias. Ideally the result would be showy and weedy.
I'd do the same thing if I had any orchid weeds.
A good measure of effectiveness would be how eager my plant friends would be to help me pull weeds.
I also have some of those little white flowered begonias running loose around here. They're pretty well behaved and are in only a few areas. I just run the lawn mower over them.
They look very much like the one I grew in my living room back in Ak., except that this one is not as red as the other.
Got a "bunch" of Oncid and Catt inter-generics recently opened and getting ready to open.
When this flush of orchids are all open I'll post pics in another thread.