A seminal scientific figure of the 20th century, Stebbins at the time of his death had established himself as the world's leading authority on plant evolution. Working with eight other scientists, he was one of the architects of the intellectual watershed known as the "evolutionary synthesis," wherein knowledge from the study of fossils, genetics, cells, and the evolutionary history of organisms was incorporated into the theories of Charles Darwin, modernizing them and creating the field of evolutionary biology. By demonstrating the now "obvious" idea that plants are subject to evolutionary processes just as animals are, Stebbins almost single-handedly established the discipline of plant evolutionary biology. The importance of this synthesis to the fields of plant breeding and biodiversity management cannot be overstated.
Stebbins' research interests included apomixis in some genera of the Aster family, the cytogenetics of peonies, and the production and analysis of species hybrids in grasses. His intensive studies on polyploidy led him to significant work on chromosome doubling, a technique he perfected and used to synthesize new species of grasses. As leader of the forage grass improvement project of the College of Agriculture, he produced over fifty new strains, representing over 20 new species, in just five years. Through all of these investigations, Stebbins formulated certain hypotheses about the relationship between chromosome pairing, fertility or sterility, and the behavior of derived polyploids in the progeny of interspecific hybrids. From related work on the developmental and biochemical genetics of stomatal patterns in grasses and mutant difference in barley, he deduced generalizations about the evolutionary importance of genetically-based mechanisms for regulating gene activity.
Stebbins was a prolific lecturer and celebrated teacher and labored indefatigably to communicate his ideas to both the scientific community and the public at large. His professional bibliography includes 252 publications and over half-a-dozen books; the landmark Variation and Evolution in Plants (1950) and Chromosomal Variation in Higher Plants (1971) are still regarded as significant in their field. His lifelong interest in the developmental aspects of genetics, in selection, and in natural hybridization, led him to become a vocal advocate for gene banks and biodiversity preservation. In 1980, the UC Regents honored the eminent plant evolutionist with the dedication of the Stebbins Cold Canyon Reserve, a 577-acre parcel of protected land set aside for research located about 20 miles west of the Davis campus. An avid naturalist and conservationist, Stebbins said the honor was far more satisfying than having his name on a campus building.