The soil was, at it appeared at first, loose and clayey, and, except the stalks of the mustard plant, there was no vegetation.

They then played the sound to one set of mustard plants and left another set in silence.

Among the wild- mustard plants there appeared a moving luminosity, having an irregular, dancing motion, as of a will-o'-the-wisp singularly agitated.

The flowers have clearly decided to just get on with it, and the scorched spot now buzzes with mustard plants and bees.

Separated from us by a row of wooden stakes and a few meters of bare soil was a sea of green, predominantly mustard plants.