It is a common theme. Coreopsis was a much simpler group of only a few specie and cultivars in the 1980s. There are now too many hybrids and cultivars to keep track of. They have been bred so extensively that they do not produce viable seed like the old fashioned types that can self sow so nicely, and were more closely related to the unimproved specie that would be found in the wild.
Breeding did more than expand the range of floral color and form. It combined the more impressive flowers with the resiliency of the toughest of perennial specie. Because they are sterile, some of the modern hybrids may not need to be deadheaded like more traditional types. Although tougher modern hybrids can capitalize on the sustainability fad, they can not proliferate and naturalize.
Coreopsis blooms in summer and autumn. The small daisy like flowers can bloom yellow, orange, red or pink, but traditional bright yellow is still the favorite color. Most cultivars are less than two feet tall and wide. A few can get nearly twice as tall. The most compact cultivars are only about half a foot tall. Coreopsis wants good sun exposure, and will bloom less and likely mildew if shaded.