I made mention on my home blog that my rhubarb was green and that I was adding elderberries to it to make it look more 'normal'. I have seen recipes that added strawberries to give colour. A few people asked if green rhubarb was safe.
Yes, it is.
The green stemmed rhubarb is a fast growing, thick stemmed hybrid. Quite safe.
The poisonous element in rhubarb is a chemical called Oxalic Acid and it is found at high levels (0.5%) in the leaves, regardless of the stem colour.
Oxalic Acid is also found in many other plants but not at the levels found in rhubarb leaves. Excessive Oxalic Acid consumption results in kidney stones (Calcium Oxalate). A lethal dose of rhubarb leaves is about 5kg.