New Zealand Spinach

I have been itching to try growing New Zealand Spinach for a number of years now and finally I bought a packet last week whilst in the USA. Not related to ordinary spinach this type (Tetragonia tetragonoides) is supposed to have been brought back from the Pacific by Captain Cook. It survives hot Summer conditions well, and you just pinch off the tops of the rambling plant and it lasts until the first frosts knock it back. I have seen it growing and I have eaten it and it tastes wonderful. But what a surprise when I opened the packet to see what the seeds looked like!! From the appearance of these seeds I guess that this is not related to the spinach / beet family that we are familiar with here in the UK. Normally a spinach or beet seed is actually 3 or 4 seeds fused in a corky layer. Some monogerm varieties have only one seed per seed. Does anyone know what happens here with New Zealand spinach? Are these strange winged pods actually containing multiple numbers of seeds? or will I get one plant out of each? Answers please.