This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A fine North American perennial, 2 ft. high, with lance-shaped leaves and large lavender-blue flowers in autumn; the variety alba has white flowers. Likes well-manured loamy soil, and may be increased by slips and seeds. Some years ago the flowers of this plant were popular for florists' work in autumn.