B127 

 (leaf 2) 



of the term boxthorn. Rliamnus is the Latinized form of the an- 

 cient Greek name for the genus. 



The buckthorns are shrubs or (mostly small) trees, with ever- 

 green or deciduous ? mostly alternate leaves, and small, usually green- 

 ish flowers, borne in axillary clusters. The fruit, which is a fleshy, 

 two- to four-seeded berrylike drupe, serves readily to distinguish 

 the buckthorns from the closely related genus Ceanothus in which 

 the fruit is a dry capsule. 



Cascara buckthorn (R. purshia'na) is probably the most common of the sev- 

 eral other species of Rhamims occurring in the West. It is a frequent, but not 

 abundant, shrub or small tree occurring in the forested mountains from British 

 Columbia to western Montana and northern California. It shares its southern 

 range with California buckthorn. However, these two species can usually be 

 distinguished by the typically arborescent habit of cascara buckthorn which, 

 moreover, has larger, thin and deciduous leaves, and prefers moist and shaded 

 sites in the timber. Cascara buckthorn is browsed very lightly by sheep and, 

 to some extent, by deer, but for all practical purposes its forage value is 

 negligible. This plant is important chiefly as the source of cascara sagrada 

 (literally, sacred bark) of commerce, which is used medicinally as a laxative. 

 Most of the bark is collected in Oregon and Washington and is preferable to 

 the California material which is often largely composed of California buck- 

 thorn. 2 3 * However, the name cascara sagrada is also used in the trade for the 

 bark of California buckthorn, "which is a popular remedy in many places in 

 California, especially among the Mexican inhabitants, whose settlements reach 

 not much farther north than San Francisco, and are, therefore, not in the 

 region of typical Purshiana." 5 



Alder buckthorn (R. alnifo'lia), as the name indicates, has alderlike foliage. 

 It is a low shrub, from 2 to 4 feet high, inhabiting moist situations from. New- 

 foundland to British Columbia, northern California, Idaho, Wyoming, Nebraska, 

 Illinois, and New Jersey. It may have some value as local sheep browse. 



Hollyleaf buckthorn (R. cro'cea) in its typical form is a low, evergreen, 

 spiny-leaved, short- and stiff-branched shrub, apparently confined to the coast 

 and coastal mountains from central to southern California, and perhaps, also, 

 Lower California. However, in its several varieties it attains tree size (up to 

 30 feet in height). In the varieties (a) iliclfo'lia (syn. R. ilicifo'lia), with the 

 leaves often golden beneath, and (b) pilo'sa (syn. R. pilo'sa), with narrow, 

 revolute, more or less hairy leaves, it extends into Arizona; in the variety (c) 

 insula'ris (syn. R. insula'ris), a form with larger, almost toothless leaves, it 

 also occurs in the islands off the coast of both southern California and Lower 

 California. The leaves of hollyleaf buckthorn are elliptic in outline; the 

 flowers lack petals ; and the fruits are bright red berries, which served as food 

 for the Indians. 



The introduced common buckthorn (R. cathar'tioa), as well as some of the 

 native species, are intermediate hosts for the crown rust disease of oats. 6 



2 Munger, T. T. THE CASCARA BARK INDUSTRY ON THE SIUSLAW NATIONAL FOREST. 

 Jour. Forestry 17 : 605-607. 1919. 



3 Chicanot, E. L. CASCARA BARK. AN IMPORTANT MINOR FOREST PRODUCT. Empire For- 

 estry Jour. [London] 5 : 102-105. 1926. 



4 Starker, T. J., and Wilcox, A. R. CASCARA. Amer. Jour. Pharm. 103 : 73-97, 147-175, 

 illus. 1931. 



B Brandegee, K. RHAMNUS CALIFORNICA AND ITS ALLIES. Zoe 1 : 240-244. 1890. 

 6 Dietz, S. M., and Leach, L. D. METHODS OF ERADICATING BUCKTHORN (RHAMNUS) SUS- 

 CEPTIBLE TO CROWN RUST (PUCCINIA CORONATA) OF OATS. U. S. Dept. Agr. Cll'C. 133, 



16 pp., illus. 1930. 



