In their native New Zealand these plants are known as spaniards, which tells us little, or spear grass, which tells us everything. They make dense tufts of slender leaves, which in most species are viciously sharp. Walk into the bigger ones, which can be a metre tall in leaf, double that in flower, at your peril. Male and female flowers are on separate plants, but both are striking, usually off white or golden yellow, and with the tall spike (aptly named) lined with - yes, you got it - vicious spines. Well worth growing, but get them in the right place, and don't attempt transplanting.

Aciphylla aurea is a mid-sized species, just a ferocious as its big brothers, with so-called golden leaves - somewhere between gold and khaki. When it flowers it sends up an armoured spike with a head of many small white flowers. An architectural plant that can be placed to keep unwelcome visitors at bay.