Question time!

Anyone know what this bush is?

I was thinking of planting it OUTSIDE the boundary wall, as a 'deterrent' (along with my crocodile) as it seems to be very thorny

Any reason why a cannot plant this for this purpose?

Thanks in advance


The bush



The thorns

Alternatively...any other / better suggestions for thorny plantings to deter attempts to climb the wall.
(I know the determined will always 'find a way', I/m thinking of all the others!)