[...] his original plan before the rolls above would be to shoot through the windows (at either the concrete ceilings or the plants, but generally into the rooms given that the roots are likely to be all over the place and not localized near their particular stalks. Say, three rooms for a start, at three different densities of 20, 40 and 80 pints of herbicide per room. Then to come back to take a look in the morning.
Sean squares his shoulders for the task ahead.
Over the course of 30 minutes, he identifies which plants are dangerous (there's nine patches of man-eaters and nine bulbs of toxin spore spitters), and carefully positions himself away from them as he begins spraying the herbicide.

His instincts turn out to be right as the plants lash out with their natural defenses when the chemicals douse them. They writhe unwholesomely as the weed killer soaks in.

After he is done doing his best to kill the offending flora, Sean retires outside, to rest until the next day. The riverboat people and the power plant fixers bunk down with the exiles to set up camp. The humans eat meals and drink water from the river but the mutants do not. The car wrecks are still on fire even when the rain picks up. They may still be burning for another hour or so.

(OC: Mark off meals eaten. Anyone got any business before we fast-forward to tomorrow?)