In the ongoing debate about risks of transgenes escape to wild plant populations, data often seem as scarce as opinions are plentiful. Scott and Wilkinson take a critical look at whether transformation of the chloroplast genome can really reduce the risk of transgene escape (see pp. 330 and 390). To test this, they used chloroplast genes as markers to track gene flow from chloroplasts of oilseed rape (a common crop plant) to wild Brassica rapa (a related weed).