122 RHAMNACE^E. 



RHAMNACE/E. 



Character of the Order. — Shrubs or small trees, with simple, alternate 

 leaves, often thorny branches, and small polygamous or dioecious flowers. 

 Calyx with 4 or 5 short deciduous teeth or sepals, valvate in the bud. Petals 

 4 or 5, very small, folded inward in the bud ; sometimes wanting. Stamens 

 as many as the sepals and alternating with them, inserted with the petals 

 on a disk which lines the tube of the calyx. Ovary 2- to 5-celled, each cell 

 1-ovuled ; style very short ; stigmas 2 to 5. Fruit a small berry or drupe 

 enclosing 2 to 5 one-seeded nuts. 



A widely distributed order of more than forty genera, about a dozen 

 of which are represented in North America — two, Rhamnus and Ceanothus, 

 comprising medicinal species. 



RHAMNUS. —Buckthorn. 



Character of the Genus. — Calyx 4- or 5-cleft, cup-shaped, lined with a 

 thin disk. Corolla : petals as many as the teeth of the calyx, small, short- 

 clawed, notched at the end, folded about the stamens ; sometimes wanting. 

 Ovary free, 2- to 4-celled. Drupe or berry containing 2 to 4 nutlets. 



Shrubs or small trees. Leaves smooth, feather-veined. Flowers small, 

 greenish, in axillary clusters. Fruit black. 



Rhamnus cathartica Linne. — Common Buckthorn. 



Description. — Calyx 4-cleft. Corolla : petals very narrow, not longer 

 than the teeth of the calyx. Fruit about the size of a pea. 



A smooth shrub, 6 to 15 feet high, with spreading branches, the smaller 

 ones often ending in a stout thorn. Leaves 1£ to 2 inches long, two-thirds 

 as wide, ovate, acuminate, serrate, with a few prominent, obliquely diverg- 

 ing veins. Flowers dioecious, thickly clustered in the axils of the leaves, 

 appearing in May and June. 



Habitat. — A native of Europe and Asia, but sparingly naturalized in the 

 Northern Atlantic States. 



Rhamnus Purshiana De Candolle. — California Buckthorn, Sacred 

 Bark. 



Description. — Calyx 5-cleft. Corolla : petals 5, two-lobed. Styles 

 rather short, united to the summit ; stigmas 3. Fruit turbinate, 3-seedecl, 

 the size of a large pea. 



A shrub or small tree, 10 to 20 feet high, with a trunk sometimes 8 or 

 9 inches in diameter. Leaves 3 to 5 inches long, 1^ to 2 inches in diam- 

 eter, sometimes slightly cordate at the base, rarely acute or with a slight 

 acumination ; the lower surface strongly pubescent, the lateral veins prom- 

 inent. Flowers umbellate, in clusters of 10 to 20. 



Habitat. — On the Pacific Coast from California northward. 



