<em>Silene latifolia</em>, or white campion (formerly <em>Melandrium album</em>)
Silene latifolia, or white campion (formerly Melandrium album), is a well-recognized historical model of plant dioecy and heteromorphic sex chromosomes. Its large genome of 3012 Mbp is organized in 12 pairs of chromosomes, one of these pairs being sex chromosomes: XY in males and XX in females. The metaphase sex chromosomes can be easily distinguished from autosomes because the Y chromosome is the largest at c. 570 Mbp, and the X chromosome is second largest, at c. 400 Mbp. The Y chromosome has at least three genic regions responsible for the development of male (staminate) flowers; one of these Y-linked genic regions corresponds to suppression of carpel development in male flowers. The absence of the Y chromosome leads to female floral development (exclusive carpel formation). This fluorescence image shows the metaphase chromosomes from a male individual with the X and Y chromosomes indicated. Chromosomes were counterstained with DAPI (diamino phenylindole, here in red) and tagged with two fluorescent DNA probes-X-43.1 subtelomeric repeat (green) and (CAT)10 microsatellite (yellow).