"I thought it was the live ones that were deadly." He sets off that way anyway, with a glance to check that she's following.

"Anything you've found effective against them -- apart from slicing their heads off? I'm short of boomerangs at the moment."

This last is not a joke, although it sounds like one -- batarangs would be ideal if these triffids are anything like the ones Dick remembers from his reading.