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 best-known member of this large genus is the Hawthorn, Quick, or May Tree, G. Oxyacantha, well known by its lobed leaves, somewhat spiny stems, and glorious masses of white (or pink) sweet-scented flowers in May and June. It is raised in thousands from seeds to form quickset hedges, and to provide stocks upon which the choicer varieties are grafted. These are numerous, the best known being the double whites, double scarlets, double pinks, and also the single-flowered scarlet known as Gumperi. The variety proecox is famous as the Glastonbury Thorn, which comes into bloom at Christmas in mild winters. There are varieties having yellow fruits, like aurantiaca and aurea.