Possible Clues:

• That's a tin like this with spikes
• A staunch sort of plant?
• One might have a tin of it like this in the shrubbery
• Prickly-leaved shrub
• Prickly plant
• A tin this way has spikes from the Mediterranean
• Cash aunt scattered round plant
• Tin like this has spines
• Plant put in a container like this
• A container so appropriate for plant