On a fine day, a flower appeared on a city street. No one noticed the odd-looking flower and so it took this opportunity to grow. The growth rate is alarmingly fast, by the time somebody notices it and informs the authorities, the alien flower has already grown too big to be eradicated by conventional means. As it grew larger, the vines started to spread throughout the city and they spurred the growth of other plants, taking up any space they could find. In just a few days, the city has to be abandoned. There are no ways of removing this alien flower without destroying the city itself.
