Spinach

Spinach is sold either as bunches or as loose leaved, baby spinach. Probably first grown in the Middle East, it was taken eastwards to China before arriving in western Europe with the Moors in the 12th century.
A relatively small plant, growing up to 30cm high, the leaves are rounded or oval to arrow shaped, and are soft and quite thick. Both the leaves and stems can be eaten after being washed well to remove any dirt or grit. Baby leaves are great in salads, use larger leaves if you plan to remove the stalks. The leaves do reduce a lot so if cooking them, buy more than you think you will need. It doesn't require much cooking, just steaming for a few minutes with no water after washing will suffice, helping to preserve the many nutrients it has.
Spinach is considered a 'superfood', although the much touted iron and calcium are bound up with oxalate and so are largely unavailable for absorption. However it does contain lots of vitamins such as A, C, E, K and B complex vitamins, protein, and many trace elements. Spinach doesn't store well and should be kept refrigerated and eaten within a few days of picking to be at its best.