The blade or green leaves of the plant contain oxalic acid crystals which can cause serious problems when eaten.
Crystals can cause the tongue and throat to swell, preventing breathing.
Therefore, the leaves should be removed before using. If the stems appear soft and mushy, do not eat. Rhubarb plants will occasionally send up flowers and seed stalks in the middle of the plants. The flowers and seed stalks can occur due to winter's chilling conditions. Stalks can also occur due to natural maturity of the plants.