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 North American hardy herbaceous perennial, 3-4 ft. high, with oval heart-shaped toothed leaves and quadrangular spikes of purple flowers from July to September. It is increased by seeds, cuttings, or division in spring. Other species are nemorosa, 1 ft., rose purple; glabra, 3 ft., creamy white; obliqua, 3 ft., violet purple. The plant known as C. barbata is more correctly known now as Pentstemon barbatus (which see).