What is Purple Oxalis?
Purple oxalis, scientifically known as Oxalis triangularis, is a perennial plant widely appreciated for its deep purple, heart-shaped leaves and delicate pink or white flowers. Also referred to as purple shamrock or false shamrock, this plant is native to South America and is a popular choice for both indoor and outdoor gardening. A distinctive characteristic is its foliage, which opens in the morning and folds up at night or on cloudy days in a response to light. While its beauty is its primary appeal for many, the culinary potential of its leaves and flowers has been recognized for centuries. The leaves and flowers offer a pleasantly tart or lemony flavor, and for this reason, the plant is sometimes referred to as 'sourgrass'.
Understanding the Role of Oxalic Acid
The tangy flavor of purple oxalis is a direct result of its high concentration of oxalic acid. Oxalic acid is a naturally occurring compound found in many edible plants, including spinach, rhubarb, broccoli, and chives. While perfectly safe in the small quantities typically found in a varied diet, the elevated levels in Oxalis necessitate caution. The primary health concern associated with excessive oxalic acid intake is its ability to bind with minerals, especially calcium, which can inhibit the body's absorption of this vital nutrient. In large doses, this can lead to nutritional deficiencies and, more severely, contribute to the formation of kidney stones. It is critical to consume purple oxalis, and any plant high in oxalic acid, in moderation. Furthermore, individuals with pre-existing conditions like kidney stones, gout, or rheumatism should avoid consuming it altogether, as it could aggravate their condition. Cooking the leaves can help reduce the oxalic acid content, making them safer for consumption.
Culinary Uses and Preparation of Purple Oxalis
For those who choose to incorporate purple oxalis into their cooking, there are several simple and creative ways to do so. The vibrant purple leaves and delicate flowers make an excellent garnish that can add both color and a citrusy tang to a dish.
Here are some popular culinary uses:
- Garnish: Sprinkle the leaves and flowers over salads, desserts, or cocktails for a pop of color and flavor.
- Salads: Add a few fresh, washed leaves to green salads to introduce a bright, lemony zest.
- Drinks: Muddle the leaves with lemon and sugar for a refreshing, sorrel-flavored lemonade. A handful of leaves can also be steeped in water to create a tart tea.
- Herbal Butter or Cheese: Blend the leaves into softened butter or soft cheese along with other herbs like parsley or chives.
- Soups and Sauces: Add cooked leaves to soups or sauces, where the heat will reduce the oxalic acid content.
- Baking: The tart flavor can be a substitute for rhubarb in desserts like pies or crumbles.
Growing vs. Foraging: An Important Distinction
When considering adding purple oxalis to your plate, it is essential to distinguish between a plant you've grown yourself and one foraged from a public or unknown area. Nurseries and garden centers often use pesticides and other chemicals to maintain ornamental plants, making them unsafe for consumption. Therefore, relying on foraged plants from yards or gardens with unknown histories is risky. The safest approach is to grow your own in a controlled, pesticide-free environment. Oxalis triangularis can be easily grown from bulbs, or rhizomes, in pots or garden beds, ensuring you know exactly what has been used on it.
Safety Precautions for Humans and Pets
The toxicity of purple oxalis is a critical consideration for any household, especially those with children or pets. The high soluble calcium oxalate content is particularly dangerous for animals, including dogs, cats, and horses. Ingestion can cause a sudden drop in blood calcium, leading to a condition called hypocalcemia.
Symptoms of pet poisoning can include:
- Excessive drooling
- Vomiting and diarrhea
- Lethargy and weakness
- Changes in urination
- Tremors
To ensure the safety of your pets, always keep purple oxalis plants out of their reach. For humans, consume in very small quantities and be mindful of the warnings for those with certain health conditions.
Comparison of Oxalis and Common Culinary Greens
| Feature | Purple Oxalis (Oxalis triangularis) | Spinach (Spinacia oleracea) | Arugula (Eruca sativa) |
|---|---|---|---|
| Oxalic Acid Content | High | High | Low to Moderate |
| Primary Use | Garnish, flavor accent, moderate quantity | Main ingredient, cooked or raw | Salad green, flavor accent, liberal use |
| Flavor Profile | Sour, lemony, tart | Mildly earthy, can be slightly bitter | Peppery, pungent, and nutty |
| Recommended Consumption | Moderate quantities, limited to occasional use | Regular consumption as part of a varied diet | Liberal consumption, staple salad green |
| Health Precautions | Avoid if prone to kidney stones, gout, or rheumatism | Requires balance in a varied diet; not for individuals prone to kidney stones | Generally safe for most individuals |
Nutritional Profile and Health Considerations
Beyond its striking appearance and tart flavor, purple oxalis offers some nutritional benefits, though its use as a primary food source is limited. It is a good source of Vitamin C and contains some Vitamin K, B vitamins, and fiber. Historically, it has been used in small amounts to treat ailments like scurvy due to its Vitamin C content. However, due to the overriding concern of oxalic acid, it is not a vegetable you can eat in large quantities. Its nutritional contribution should be viewed as a minor addition, primarily for flavor and as a novel garnish, rather than a significant part of a healthy eating plan. For significant nutrient intake, it is far more effective and safer to rely on staple greens like spinach, kale, and other low-oxalate vegetables.
Conclusion: Moderation is Paramount
In conclusion, the question, 'Are purple Oxalis edible?', is answered with a qualified yes—they are, but only in moderation and with careful attention to safety. This beautiful houseplant offers a unique, lemony flavor that can enhance salads and other dishes when used as a garnish or in small quantities. The key takeaway is the plant's high oxalic acid content, which can be toxic in large amounts and poses risks to individuals with certain health conditions. For those who wish to consume it, it is best to grow your own to ensure it is free from harmful pesticides. Most importantly, pets should be kept away from the plant entirely due to its toxicity. By understanding and respecting these limitations, purple oxalis can be a safe and flavorful addition to a well-considered and balanced diet. For those interested in exploring wild edibles responsibly, the Foraging & More website provides useful guidelines on sourcing and preparation, including their profile on wood sorrel.
