The veggie burger has emerged as the latest battleground over traditional American values.

Several states have passed labelling laws banning the use of the word meat - and even meat-related terms such as burger or hot dog - for plant-based products.

The row has pitched high-tech food innovators against the ranchers' trade body US Cattlemen's Association and mainly conservative politicians in America's rural heartland.

Environmentalists extol the planet-friendly virtues of plant-based meat, arguing that it is responsible for far lower methane emissions than cattle.

From the other corner conservatives, like Texas Republican senator Ted Cruz, have been scathing about vegan food.

During his bitter election battle with Beto O'Rourke, he claimed on Twitter that the Democrats would ban barbecues across the state.

Mississippi, Missouri, Louisiana and Arkansas have led the way in passing strict labelling laws, imposing fines on companies who transgress.