The sweet pea, Lathyrus odoratus, has a well-documented history of the
development of its cultivars in various parts of the world. Measureme
nts of genome size, using flow cytometry, and observations on the kary
otypes, as well as the analysis of meiotic pairing of F1 hybrids (betw
een the wild sweet pea and two modern cultivars), all show that this d
evelopment has not been accompanied by changes in karyotype or genome
size. However, the cultivars do differ in pollen size and guard cell c
hloroplast number, both characteristics that have been suggested to be
controlled by the nucleotype; however, this is clearly not the case i
n L. odoratus.