What vegetable would you find in the Greek yogurt dip called tzatziki?

Tzatziki is made of strained yogurt (usually from sheep or goat milk) mixed with cucumbers, garlic, salt, olive oil, and sometimes lemon juice, and dill or mint or parsley. The Greek-style tzatziki sauce is commonly served as a meze, to be eaten with bread, fried eggplant, or zucchini. Some variations are made with cattails or purslane. Purslane is called glistrida in Greek and this may be called glistrida me yiaourti meaning "purslane and yogurt salad" rather than tzatziki. One simple recipe calls for purslane, olive oil, red wine vinegar, and dill. Another is made with purslane, mint, cilantro, parsley, and ground coriander, along with the standard yogurt-cucumber base.

Source: Wikipedia