This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A genus closely related to the Cistus, and having several species of shrubby plants suitable for dry sunny places. In most cases the flowers are yellow with a dark crimson or purple blotch at the base of the petals. The best-known kind is vulgare, a trailing British plant having single- and double-flowered varieties with shades of yellow, rose, magenta, crimson, etc. The Portuguese H. formosum has yellow flowers with purple blotches, and grows about 4 ft. high.