"Agastache syn. Brittonastrum ('giant hyssop') is a genus of 9–12 species of aromatic flowering herbaceous perennial plants in the family Lamiaceae, native to eastern Asia (one species) and North America (the rest).
Most species are very upright, 0.5–3 m tall, with stiff, angular stems clothed in toothed-edged, lance shaped leaves ranging from 1–15 cm long and 0.5–11 cm broad depending on the species. Upright spikes of tubular, two-lipped flowers develop at the stem tips in summer. The flowers are usually white, pink, mauve, or purple, with the bracts that back the flowers being of the same or a slightly contrasting color. Leaf tips can be eaten and made into teas.
They are easily grown in moist, well-drained soil and prefer a sunny position. Winter hardiness varies; the hardiest is A. foeniculum, hardy to USDA plant hardiness zone 1 in the north of its range; A. nepetoides, A. rugosa, A. scrophulariifolia and A. urticifolia are hardy to zones 3–5 in the northern parts of their ranges. Propagate from seed or cuttings. Popular cultivars include A. cana 'Heather Queen'. The cultivar 'Blue Fortune' has gained the Royal Horticultural Society's Award of Garden Merit."
Taken from wikipedia's page at: http://en.wikipedia.org/wiki/A...