Although natural hybridization in the genus Narcissus (daffodils) is not infrequent, that between phylogenetically distant species differing in basic chromosome number involves significant genome changes. Using PI and DAPI flow cytometry, Marques et al. compare variation in genome size between natural populations of two hybrids (N. ×perezlarae and N. ×alentejanus) and their progenitors as well as F1 reciprocal synthetic hybrids. Natural hybrids exhibit a wide population variation, with higher than expected genome size values, especially as determined with DAPI. Genome size in artificial hybrids is largely dependent on the direction of the cross, due to a strong maternal effect.