Nynaeve: Even if they are not as useful as Healing, herbs are a part of the healing arts and understanding them cannot hurt a sister's comprehension & use of her Talent. All the sisters I know are very resistant to this concept, and even belittle me for making use of herbal medicines.
Egwene: Hah! That's where you're wrong Nynaeve! In her rooms in the Tower, Suana has a garden set up where she grows carrots and radishes.
Nynaeve: ...Wow. Nothing like finding out you have just wasted all those years I spent teaching you about medicine.