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.
The Common Laburnum is well known by its grey-green leaflets and drooping racemes of bright yellow Pea-like flowers in April and May. There are several varieties, including aureum, with golden leaves; cristatum monstrosum, a curious crested-leaved variety; Parksi and Watereri are both fine varieties with longer and deeper coloured racemes, and quercifolium has the leaflets lobed like Oak leaves. The purple Laburnum, Adami, is famous as a "graft hybrid" between Cytisus jmrpureus and the ordinary kind; it has sometimes yellow, sometimes purple flowers, and sometimes mixed. The Scotch Laburnum, alpinum, has large yellow flowers in June. All kinds grow in ordinary soil. Choice varieties are grafted on stocks of the common form which are easily raised from seeds.