Oxalic Acid Metabolism in Begonia semperflorens

The primary accumulation of oxalate in the early seedling stages accompanies the synthesis of both protein and reserve carbohydrate. A further accumulation accompanies the normal growth of the young expanding leaf. Free oxalic acid accounts for most of the total oxalate content at the various stages. The form in which nitrogen is supplied to the young seedling (ammonium nitrogen or nitrate nitrogen) markedly affects both growth and the amount of oxalate formed. More oxalate and poorer growth is found in plants grown on ammonium as a sole source of nitrogen. In the mature leaf the oxalate content remains constant under a wide variety of different conditions. No enzyme systems could be detected which might be active in the formation of oxalate. It is concluded that oxalic acid is only formed during rapid growth in Begonia, and that once formed it takes little further part in metabolism.