178 THE BUCKTHORN FAMILY. 



The JE. latifolius, from the continent of Europe, the E. atropur- 

 pureus, from North America, and some other exotic species, are occa- 

 sionally planted in our shrubberies. 



XXIII. THE BUCKTHORN FAMILY. UHAMNACEiE. 



An extensive family, widely dispersed over the globe, but con- 

 fined in Britain to the single genus Buckthorn. The exotic genera 

 all agree with that one, and differ from the adjoining families in 

 the position of the stamens, alternating with fche sepals, the petals 

 either small and opposite to (or underneath) the stamens, or 

 wanting. 



The CeanotJiuses of our gardens belong to this family. The Grape 

 Vine, the Virginian creeper, and other species of Vitis have the same 

 relative position of the stamens and sepals ; but the stamens being more 

 decidedly hypogynous, and the habit different, they form the indepen- 

 dent Vine family. 



I. BUCKTHORN. RHAMNUS. 



Shrubs, with alternate undivided leaves, and small green flowers on 

 short pedicels, usually clustered in the axils of the leaves. Calyx with 

 4 or 5 short, deciduous teeth or sepals. Petals none or very small. 

 Stamens 4 or 5, alternating with the teeth of the calyx and opposite 

 the petals, inserted on a disk which lines the base of the calyx. Ovary 

 free, 3- or 4-celled, with one erect ovule in each cell. Style very short. 

 Fruit a small berry (or drupe) enclosing 3 or 4 small one-seeded nuts. 

 Embryo in a fleshy albumen. 



A considerable genus widely spread over the northern hemisphere, 

 both in the new and the old world, penetrating into the tropics, with a 

 few southern species. 



Leaves minutely toothed. Branches often thorny. Flowers 



dioecious ; stamens 4 , . . . 1. Common B. 



Leaves entire. No thorns. Flowers hermaphrodite ; stamens 5 2. Alder B. 



The evergreen Alaternus of our shrubberies is a species of Buck- 

 thorn (JR. Alaternus) from southern Europe. 



