From 1960, Stebbins was instrumental in the establishment of the Department of Genetics at the University of California, Davis, and was active in numerous organizations involved in the promotion of evolution, and of science in general.

In California, Stebbins was enrolled at the Cate School in Carpinteria where he became influenced by Ralph Hoffmann, an American natural history instructor and amateur ornithologist and botanist.

[6] Stebbins started graduate studies at Harvard in 1928, initially working on flowering plant taxonomy and biogeography—particularly that of the flora of New England—with Merritt Lyndon Fernald.

Stebbins chose to concentrate his doctoral work on the cytology of plant reproductive processes in the genus Antennaria, with cytologist E. C. Jeffrey as his supervisor and Fernald on his supervisory panel.

Jeffrey and Sax argued over Stebbins's dissertation, and the thesis was revised numerous times to accommodate their differing views.

Here, Stebbins's interest was captured by talks given by Thomas Hunt Morgan and Barbara McClintock, who spoke about chromosomal crossover.

Stebbins reproduced McClintock's crossover experiments in the peony, and published several papers on the cytogenetics of Paeonia, which established his reputation as a geneticist.

[7] In 1935, Stebbins was offered a genetics research position at the University of California, Berkeley working with geneticist E. B. Babcock.

Babcock needed assistance with a large Rockefeller-funded project characterizing the genetics and evolutionary processes of plants from the genus Crepis and was interested in developing Crepis into a model plant, to enable genetic investigations similar to those possible in the model insect Drosophila melanogaster.

Like the genera that Stebbins had previously studied, Crepis commonly hybridized, displayed polyploidy (chromosome doubling), and could make seed without fertilization (a process known as apomixis).

In The American Species of Crepis, Babcock and Stebbins described the concept of the polyploid complex, and its role in plant evolution.

They also showed that hybridization in the polyploid complex could provide a mechanism for genetic exchange between diploid species that were otherwise unable to breed.

Their observations offered insight into species formation and knowledge of how all these complex processes could provide information on the history of a genus.

He became associated with a group known as the Bay Area Biosystematists, which included botanist Jens Clausen, taxonomist David D. Keck, physiologist William Hiesey and the evolutionary geneticist Theodosius Dobzhansky.

He produced an artificial autotetraploid grass from the diploid species Ehrharta erecta through treatment with the chromosome doubling agent colchicine.

[15] In the book Stebbins argued that evolution needed to be studied as a dynamic problem and that evolution must be considered on three levels: first, that of individual variation within an interbreeding population; second, that of the distribution and frequency of this variation; and third, that of the separation and divergence of populations as the result of the building up of isolating mechanisms leading to the formation of species.

One of the book's most original chapters used the cytogenetics work of C. D. Darlington to show that genetic systems like hybridization and polyploidy were also subject to selection.

Variation and Evolution in Plants continues to be widely cited in contemporary scientific botanical literature more than 50 years after its publication.

Stebbins regarded his contribution to the modern synthesis as the application of genetic principles already established by other workers to botany.

[20] At Davis, the focus of his research changed to incorporate newer areas, such as developmental morphology and genetics in crop plants, including barley.

Through the society, he created an active field trip program to increase interest in the native flora of California and to document rare plants.

Ledyard Stebbins was in the latter category; neither fish nor fowl, he frequently failed to receive credit for work in some areas, usually at the hands of narrower colleagues.

Few, however, have challenged his contributions to plant evolutionary biology, nor questioned his ability to synthesize disparate literature into a coherent framework.

His ability to read quickly, recognize novel insights, digest new material, and then integrate the knowledge were the hallmarks of his scientific work style.

The UC Davis Herbarium maintains a G. Ledyard Stebbins student grant program, established in celebration of his 90th birthday.