I know lantana is considered a noxious weed in many parts of Australia (including Western Australia) but there are some that are still favoured as they don't appear to take over from other plants. One I particularly like is the yellow lantana and we have one growing in our back garden and doing very well (even competing with the weeds).
They are a very hardy plant. There are several planted near our small local shopping centre and I imagine they do get watered occasionally although I have never seen this happen. No matter they continue to thrive but do not grow very large. This makes this so suitable for small borders.
Another "L" plant I have always loved is the larkspur although I think most people usually call it a delphinium. I've never attempted to grow them but I do so love the blue ones.
Now to search for some pretty flowers beginning with "M".