It was said that the Plants at Fukushima had mutated due to radiation after a tsunami in March of 2011. The radiation in the aria the daisies were said to be was 0.5 uSv/h at 1m above the ground. That is only slightly above the normal radiation and is classified as safe for medium to long term habitation. This wouldn't make any of the flowers mutate.
Where do you get reliable information?
Personally, I get my information anywhere, but for reliable info, Snopes and factcheck are always handy. Yes even those sights can have slip ups and be wrong, but the sights are made to be for facts.
How can you tell the information is reliable?
Usually if the website is a .org, it can be reliable. what i go with is if the information i am looking for is repeated on other sights.
How important is factual information to the success of our democracy?
To be honest, I think the more facts we have about the situation, the better. The lies that are spread around don't help any of the situations forever. Everything gets found out eventually. The false information gets spread around, and the people who read it will believe it. People who were actually there when the thing was discussed, will get their word out, and will win.