Origins and Botanical Classification
While often grouped together as 'leafy greens,' kale and arugula have distinct botanical profiles and histories. Both are members of the Brassicaceae family of cruciferous vegetables, which also includes broccoli, cabbage, and cauliflower. However, they are different species within this family. Kale is classified as Brassica oleracea, a species known for its hardy, winter-harvested forms. Arugula, or Eruca vesicaria, is more closely related to radishes and is technically an herb, though it is used as a salad green.
Kale's roots trace back to the Eastern Mediterranean and Anatolia around 2000 BCE, cultivated as a staple vegetable for centuries. Its ability to withstand cold weather made it a popular crop in many ancient and medieval European cultures. Arugula has a similarly long history, originating in the Mediterranean region and dating back to ancient Roman and Old Testament times, where it was celebrated for its peppery flavor.
Taste, Texture, and Appearance Differences
One of the most noticeable distinctions between these two greens is their sensory profile.
Taste Profile
- Kale: The flavor of kale depends on the variety and maturity. Mature kale has a robust, earthy, and sometimes slightly bitter taste. Baby kale is milder and sweeter. The flavor becomes less harsh and sweeter when cooked.
- Arugula: Arugula is famous for its distinctive peppery, slightly spicy, and mustard-like flavor. The younger the leaf, the milder the taste, while mature arugula can have a much more pungent bite.
Texture and Appearance
- Kale: Known for its firm, fibrous, and hearty leaves. Varieties include curly kale, with its ruffled edges, and lacinato (dinosaur) kale, with its flat, bumpy leaves. The leaves are tough and require massaging or cooking to become tender enough for many raw preparations.
- Arugula: Features more delicate, tender leaves with a smooth texture. The leaves can be spoon-shaped or have deeply lobed, wing-like formations. Baby arugula is even more tender than its mature counterpart.
Culinary Uses and Preparation
Their different flavors and textures mean that kale and arugula are best suited for different culinary applications.
Kale Applications
- Salads: Mature kale must be massaged with a little oil to soften the fibrous leaves, while baby kale can be used as is.
- Smoothies: Kale's sturdy nature makes it an excellent green for blending into smoothies without becoming watery.
- Sautéing and Soups: Kale holds up well to heat and can be sautéed with garlic or added to soups and stews, retaining its texture even after cooking.
- Baked Kale Chips: The leaves can be baked until crispy for a nutritious snack.
Arugula Applications
- Raw Salads: Arugula's peppery flavor is perfect for raw salads, often paired with milder ingredients like fresh mozzarella or pears.
- Pizza Topping: The tender leaves are often added to pizzas and flatbreads right after they come out of the oven.
- Pesto: Arugula can be used to make a spicy, peppery pesto, sometimes mixed with basil.
- Sandwiches and Wraps: Adds a zesty bite to sandwiches and wraps without overpowering other ingredients.
- Lightly Sautéed: Unlike kale, arugula is typically only cooked for a very short time to avoid losing its delicate texture.
Nutritional Comparison
Both kale and arugula are incredibly nutritious, but their specific vitamin and mineral compositions differ slightly.
| Nutrient | Kale | Arugula |
|---|---|---|
| Vitamin K | Very high (significantly higher) | Lower |
| Vitamin A | High (significantly higher) | Lower |
| Vitamin C | Higher | Lower |
| Calcium | High, but not as bioavailable as in arugula | Higher (more bioavailable) |
| Iron | Lower | Higher |
| Fiber | Higher | Lower |
Growing Conditions
The difference between the two plants is also evident in their ideal growing environments. Kale is a cool-weather vegetable that thrives in colder temperatures and is often grown as a winter crop. It can be more tolerant of different light conditions but generally prefers full sun. Arugula is also a cool-season green but is known for being more adaptable to temperature shifts. It matures much faster than kale and is more prone to bolting (producing flowers and turning bitter) in hot weather.
Conclusion: Not Identical, But Both Beneficial
In summary, the notion are kale and arugula the same thing is a common misconception, but the answer is a definitive 'no.' While both are highly nutritious members of the cruciferous family, they are distinct plants with unique flavors, textures, and culinary uses. Kale is the hearty, earthy, and more fibrous green, better suited for cooking and robust dishes. Arugula is the delicate, peppery herb, ideal for adding a zesty bite to salads and sandwiches. Incorporating both into your diet can provide a diverse range of nutrients and add different dimensions of flavor to your meals. A-Z Animals offers more insight into these differences.
Frequently Asked Questions
Why does arugula taste peppery?
Arugula's peppery, mustard-like flavor comes from sulfur-containing compounds called glucosinolates, which are also found in other cruciferous vegetables.
Can you substitute arugula for kale?
Yes, you can substitute arugula for kale, but it depends on the recipe and the desired outcome. Baby kale is a better substitute for raw arugula in salads, while regular arugula is a viable substitute for kale in soups, though the flavor profile will change.
Is kale healthier than arugula?
Neither is definitively "healthier," as both offer unique nutritional benefits. Kale is higher in vitamins K and A, while arugula contains more iron and calcium. A balanced diet often includes both.
What is arugula also called?
Arugula is also known as rocket, roquette, and rucola, particularly in Europe.
Why is kale considered a superfood?
Kale earned its superfood reputation due to its high concentration of vitamins, minerals, and antioxidants, and its low-calorie, high-fiber profile.
Can I eat arugula stems?
Yes, the stems of arugula are edible and generally tender, especially in baby arugula. The stems of more mature leaves can be slightly tougher but are still fine to eat.
Does cooking kale and arugula change their nutritional value?
Yes, cooking can slightly alter the nutritional value of both greens. Cooking kale softens its fibers and can make some nutrients more bioavailable, while overcooking arugula can diminish its vitamin C content and reduce its peppery flavor.
