Answer:  Camu-camu (Mycaria dubia) -- a low-growing shrub found in swampy or flooded areas of the Amazon rainforest.    In addition to vitamin C, it provides iron, niacin, riboflavin, phosphorus, potassium, beta-carotene, calcium, leucine, protein, serine, thiamin, and valine.

Source: http://www.rain-tree.com/camu.htm