Bottle gourds have different shapes and are found in Africa and Asia. In Europe, they were seen more during the Roman times. Researchers studied ancient bottle gourd seeds and DNA from Roman sites in France and Switzerland. The seeds varied in size and shape, suggesting different types of bottle gourds were present in Europe. The DNA of the bottle gourd from France and a commercial cultivar showed they came from Asia. This supports the idea that Asian bottle gourds were in Europe early on. The seeds from Switzerland didn't have Asian DNA markers, but had DNA matching a plant family called Cucurbitaceae, showing that DNA can be preserved in old, waterlogged plant remains.