26 FAMILIAR TREES 
sepals are generally united into a distinct cup below, 
the fleshy inner surface of which secretes the honey, 
whilst the petals and stamens spring from its 
margin. Another leading characteristic is that the 
stamens each stand in front of one of the petals, 
instead of between them, which latter is the case in 
the Spindle-tree. 
The fruit in most members of the Order is fleshy 
externally, whilst internally it consists of three, or less 
commonly two or four, hard one-seeded stones. It is 
the fleshy portion of the berries of the Buckthorns 
that yields the various colouring substances which 
constitute one of the chief economic products of the 
group; and fruit, bark, and, to some extent, the whole 
plant contain bitter, and sometimes astringent, 
principles often strongly purgative and employed as 
such medicinally. Thus a Mediterranean species, 
Rhamnus “infector'ius L, is much grown at 
Kaisaryeh in Asia Minor, the ancient Cesara in 
Cappadocia, and its unripe fruits are exported from 
Smyrna under the name of Persian or Yellow Berries. 
Other species, such as #. saxa'tilis L., from South- 
Eastern Europe, R. alater’‘nus L. and R. oleoi‘des L., 
from the Western Mediterranean area, and our 
British species R. catharticus, yield some of the 
berries of commerce, those from France, known as 
Avignon Berries, being considered inferior to. the 
Asiatic. These fruits are used to give a yellow colour 
to morocco leather. The ripe berries of the British 
and Asiatic species alike, with the addition of alum 
or lime-water and gum arabic, form the sap-green or 
bladder-green of painters. Ripe Buckthorn-berries 
