The Indian potato vine. This twining plant has clothed its tripod with bluish pinnate leaves, through which emerge, rather reluctantly, closely packed racemes of plum mousse coloured flowers, each looking like a medieval helmet and together looking like some impenetrable formation.
The common name is at once misleading and indicative. It does produce fine, tasty, potato-like tubers but it is native to the Americas, not India. To add to its geographical confusion, it is only Japan that has managed to farm this promising food source to harvest.