"night vision" is picking up a thermal image (infared from the guys body hiding in the bushes that the helicopter is chasing
a thermal image can be produced from the heat of grow lights when they are in attics etc
but not shiled by layes of concrete walls inside houses
you seem to be saying that the plant itself is emitting a heat image that can be detected, and a picture of the leaf produced from this plant emitting thermal image
i think you have got that bit in a muddle , as far as i know plants don't emit measurable heat themselves like grow lights and folk being chased by helicopters do
just a thought
peace