Respiratory System Herbal Supplement Stinging Nettle Blend Liquid Extract We prepare our Nettle Extract from the fresh (undried) leaf (65%) and the dry mature seed & calyx (35%) of Urtica dioica plants which are Certified Organically Grown or Custom Wildcrafted in their natural wild habitat. To assure optimal potency, the leaf is harvested in early spring and the seed & calyx are harvested in late summer. They are each extracted separately according to their individual biochemistry and are then blended together to produce a full-spectrum extract. Our Nettle is never fumigated or irradiated.