Ask Mr. Smarty Plants

Hybrids are the offspring of crosses between two different species in the same genus or, rarely, two species in different genera.  Most hybrids are sterile and unable to sexually reproduce, though many spread very successfully through vegetative means, e.g., rhizomes, stolon, bulbs, etc.  Though many hybrids are produced by intentional means by man, naturally hybrids arising in the wild are also common.  Some hybrids, both natural and man-bred, are capable of sexual reproduction

Cultivars may be hybrids of natural or man-made origin or they may simply be naturally-occurring species that has been singled out for horticultural reasons.  A cultivar is nothing more than a plant that has been selected and propagated for some desirable characteristic (prettier flowers, more compact growth habit, tastier fruit, higher fruit yield, etc.) and given a cultivar name.

The term, cultivar, is a portmanteau of cultivated variety.  The term was coined early in the 20th century to differentiate between cultivated varieties of garden plants and botanical varieties which are always of wild origin. 

So a native wildflower that has been selected for some desirable horticultural characteristic and given an official cultivar name is indeed an example of how a wild plant can become a cultivar with no more intervention than cultivation and naming.