This section is from the book "The Gardener V3", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
This furnishes some of the most splendid flowers of spring. The later-flowering varieties, which are derived from T. Gesneriana, are unsurpassed in the variety and brilliancy of their colours; and the earlier-flowering ones, which, if less varied, are not less brilliant, are derived chiefly from T. suaveolens, both species being natives of southern Europe. Two of the best early-flowering species are T. Clusiana and T. praecox, the latter bright scarlet, the former purple, white, and red.
Craigleith Nursery, Edinburgh.