Plant people

I'm searching for a manga which I've read like two years ago (?) and I don't know the name or genre anymore. I don't remember that much about it unfortunately.

There are people who eat certain seeds and then they gain the ability of the plant - not all seeds do that though. But the government thinks of them as monsters (or something like that), so they try to either kill these people or inprison them for experiments. Or something along these lines.
The protagonist lives with his father (foster father?) who cares a lot about plants and makes experiments to get these seeds but kinda... the police storms the house and sets it on fire, so the father stuffs the protagonist a seed in his mouth and makes him escape. Prota-kun gets his plant powers but passes out somewhere and is found by nice people who help him. He makes friends with the son of his helpers. But the goverment/police/Idk try to catch a lot of plant people so they say "We need young men to help construct a buildung and it's mandatory". Prota and friend are drafted in and have to work very hard but the people with plant power need water or else something happens (I forgot what exactly) and the government/police/idk mix something in the water of the workers which won't do anything to the humans but will the plant people make lose control and go on a rampage. Prota-kun is kinda special though so he gets taken away from a high-ranking person. The last thing I remember is that Prota and the high-ranking person are in a carriage and then there is a... landslide? And high-ranking person thinks Prota is gonna escape because that would be his chance but Prota decides to stay.

Yeah, it'd be nice if someone could understand my explanation and tell me which manga this is ^^