The Toxic Culprit: Rhubarb Leaves
The primary and most dangerous part of the rhubarb plant that is inedible is the leaves. These large, heart-shaped leaves contain high concentrations of a corrosive acid called oxalic acid, which can be poisonous if ingested in sufficient quantities. While the stalks also contain this substance, the concentration is significantly lower and safe for consumption.
During World War I, some individuals tragically became ill and died after being advised to eat rhubarb leaves as a vegetable substitute. While fatalities are rare and typically require consuming large quantities, the severe health risks mean the leaves should be avoided entirely. Symptoms of rhubarb leaf poisoning can range from mild issues like nausea and stomach pain to much more serious complications, including kidney damage and seizures.
Symptoms of Oxalic Acid Poisoning
- Gastrointestinal Distress: Nausea, vomiting, and abdominal pain are common initial symptoms.
- Burning Sensation: A burning feeling in the mouth and throat can occur after ingestion.
- Kidney Issues: In severe cases, the accumulation of calcium oxalate crystals in the kidneys can lead to kidney stones or even kidney failure.
- Neurological Effects: Extreme poisoning can manifest as muscle twitches, cramps, and seizures.
Safe and Savory: The Edible Rhubarb Stalks
In stark contrast to the leaves, the colorful stalks (petioles) are the delicious and perfectly safe part of the rhubarb plant. These stalks, which can range from vivid ruby red to pale green, are the part used in everything from pies and jams to sauces and crumbles. As a general rule, the redder the stalk, the sweeter and less tart the flavor will be.
Preparing Rhubarb Stalks
- Remove and Discard Leaves: Immediately upon harvesting or purchasing, cut the toxic leaves completely off the stalks and dispose of them properly. Do not compost them where animals might reach them.
- Wash the Stalks: Rinse the stalks thoroughly under cool water to remove any dirt or debris.
- Trim and Peel (Optional): For older or tougher stalks, use a vegetable peeler or a sharp knife to remove the tough, stringy outer layer. Younger, forced rhubarb may not require peeling. Trim the base and top of the stalk.
- Chop: Cut the stalks into your desired length, typically 1-inch pieces, for cooking.
Harvesting and Garden Safety
When harvesting rhubarb from your garden, it is important to follow safe practices to protect yourself and your plants. Harvest stalks by holding the base and twisting gently to pull them from the crown. Never cut the stalks, as this can lead to rot in the remaining stump. Ensure you only take about one-third of the plant's stalks at a time to allow it to continue growing vigorously. The leaves should be immediately and completely separated from the stalks and disposed of safely, away from pets or small children. Compost is a suitable destination for the leaves, as the oxalic acid breaks down naturally during decomposition.
Rhubarb Plant Parts Comparison
| Feature | Rhubarb Leaves | Rhubarb Stalks | Notes |
|---|---|---|---|
| Edibility | Highly toxic | Edible and delicious | The leaves contain poisonous oxalic acid. |
| Oxalic Acid Level | Very high | Low and safe | Cooking further reduces oxalic acid levels in stalks. |
| Culinary Use | None (Poisonous) | Pies, jams, sauces | The stalks are primarily used in desserts and sweet dishes. |
| Taste | Extremely bitter | Tart and slightly sweet | The taste profile is distinct and enjoyable when prepared. |
| Appearance | Large, umbrella-like | Long, celery-like stalks | Stalk color can indicate sweetness and variety. |
Conclusion
It is essential to understand that only the stalks of the rhubarb plant are edible. The large, green leaves contain high levels of toxic oxalic acid and must be completely removed and discarded before cooking or consumption. By following safe preparation and harvesting guidelines, you can enjoy the distinctive tart flavor of rhubarb while ensuring your health and safety. Remember to always stick to the stalks and leave the leaves behind. If accidental ingestion of leaves occurs, especially in large amounts, seek immediate medical attention.
Frequently Asked Questions
1. What is the poisonous substance in rhubarb leaves?
The toxic compound in rhubarb leaves is oxalic acid.
2. Can you cook rhubarb leaves to make them safe?
No, cooking does not neutralize the high levels of oxalic acid in the leaves enough to make them safe for consumption.
3. Is the redder rhubarb sweeter?
Yes, as a general rule, the redder the rhubarb stalk, the sweeter the flavor tends to be.
4. What happens if a pet eats rhubarb leaves?
Like humans, pets should not ingest rhubarb leaves due to the risk of oxalic acid poisoning, which can cause severe illness.
5. Can rhubarb leaves be added to compost?
Yes, it is safe to add rhubarb leaves to your compost pile, as the oxalic acid breaks down during the decomposition process.
6. What are the symptoms of rhubarb leaf poisoning?
Symptoms can include nausea, vomiting, abdominal pain, a burning sensation in the mouth, and, in severe cases, seizures and kidney damage.
7. How should you harvest rhubarb stalks?
Harvest stalks by gently pulling and twisting them from the base of the plant, rather than cutting them, to prevent rotting.
8. Can you eat raw rhubarb stalks?
Yes, the stalks can be eaten raw, but they are very tart. They are typically cooked and sweetened for use in recipes.
