This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
The habitat of this plant is hedges, thickets, woods, chiefly on chalk. The plant has the shrub habit. The plant is rigid, much-branched, with black bark. The branches are opposite and spinous. i The leaves are grouped at the end of the shoots, egg-shaped, round, oval, coarsely toothed, the serratures curved, glandular, with spreading nerves, shortly-stalked. The thorns are terminal. The young leaves are downy below. The leafstalks are longer than the awl-like deciduous or falling stipules. The flowers are yellowish-green, solitary or grouped in the axils of the leaves on previous year's wood, the calyx of the male flower bell-shaped, of the female cupular, with acute sepals. The flowers have the parts in fours. The plant is dioecious, but each has rudimentary male ' or female flowers respectively. There are four forms: long-styled male, short-styled male, long-I styled female, short-styled female. The styles are 4- or 2-5-lobed, four united half-way up. The ' flowers are sweet-scented. The drupe is rounded, black, with four stones, which are inversely egg-j shaped, grooved on the back. The seeds are notched. The plant is 5-10 ft. high, flowering from May to July, and is a deciduous shrub.