Blue flowers are rare in nature, and for good reason: the color is usually the result of mutations and quirks of acidity levels rather than an actual blue pigment. That makes genetically engineering a blue flower tricky, since you can't just make a straightforward tweak and expect a garden full of unnatural hues. Scientists have just managed a breakthrough, though. They've produced the first truly blue chrysanthemum (above) by splicing in genes from two naturally blue flowers, the butterfly pea and Canterbury bell. The modifications shifted the plant's acidity level, turning normally reddish pigments to the blue you see above.