Aconitum napellus. Majestic spikes of attractive, poisonous, helmet-like blue flowers that make great border plants. Likes rich, moist, well-draining soil, in full sun to part shade. Seeds need stratification. Aconite is an important homeopatic medicine that is used to treat fear, anxiety, and restlessness; acute sudden fever; symptoms from exposure to dry, cold weather or very hot weather; tingling, coldness, and numbness; influenza or colds with congestion; and heavy, pulsating headaches.