Species: Frangula purshiana

Cascara False Buckthorn

Species

Plants

Encyclopedia of Puget Sound

Classification

Kingdom

Plantae

Phylum

Anthophyta

Class

Dicotyledoneae

Order

Rhamnales

Family

Rhamnaceae

Genus

Frangula

NatureServe

Source:
ELEMENT_GLOBAL.2.157732

Classification

Other Global Common Names

Cascara Buckthorn - Cascara buckthorn

Informal Taxonomy

Plants, Vascular - Flowering Plants - Buckthorn Family

Formal Taxonomy

Plantae - Anthophyta - Dicotyledoneae - Rhamnales - Rhamnaceae - Frangula - J.O. Sawyer Jr. in Hickman (1993) briefly characterizes but does not formally recognize Rhamnus purshiana var. annonifolia (Greene) Jepson, which as Rhamnus anonaefolia Greene, 1896 is treated as a synonym of the species (without discussion) by Abrams (1951) and Munz and Keck (1959).

Ecology and Life History

Short General Description

A small tree (or a shrub in drier habitats, such as the southern parts of its range; Collingwood and Brush 1965, Habeck 1992, Kricher 1993) with glossy parallel-veined leaves, small greenish-yellow flowers in stalked clusters, and small purplish-black berries. Growing to (3-) 9-35 (-45) feet high and 6-15 (-36) inches in diameter, with smooth dark brown to ashy gray thin bark developing thin scales (well illustrated in Collingwood and Brush 1965). The deciduous leaves are tufted at branch tips. The (usually) bisexual flowers occur in clusters of 8 to 25 (-50) that are arranged in long-stalked umbels. The black or dark purplish to bluish berries (drupes) are round (about 1/4 - 1/2 inch or 6-14 mm in diameter) and slightly fleshy, with usually 3 (or 2) smooth olive-green hard seeds. In California the species may flower in April-July, with the fruit ripening in July-September (Collingwood and Brush 1965, Vance et al., in press).

Ecology Comments

Frangula purshiana is essentially an understory species which is very shade tolerant, and slow growing (Kricher 1993, Norse 1990). Cooke and Pratt (1998) have data on the size and growth rate of this species in low-elevation wetlands in the Puget Sound Basin of Washington. Habeck (1992) has summarized some information on growth rates. The species is considered a competitor plant species by forest vegetation managers concerned with producing crop trees. The competing "weed" [sic] species are those typical of sites being reforested in Washington, Oregon and northern California (Norse 1990, VMRC 1999). The species is usually top-killed by fire, but will sprout from the root crown after low-intensity fire. In southern Oregon, natural low-intensity fires in its habitat may occur at intervals of 30-60 years, to 100-320 years; in some associations that include the species, high-intensity fires may occur every 60-150 years. Its primary ecological role may be that of a long-lived invader species (Habeck 1992). The species is a prolific seeder. Birds eagerly eat the berries, and disperse the seeds (Collingwood and Brush 1965, St. John 1963, Schopmeyer 1974, Habeck 1992).

Conservation Status

NatureServe Global Status Rank

G4G5

Global Status Last Reviewed

2009-03-24

Global Status Last Changed

2009-03-24

Distribution

Conservation Status Map

Global Range

Southwestern Canada (British Columbia) and northwestern United States (Washington, Oregon and California, also Idaho and Montana). On the Pacific slope from southwestern British Columbia (including much of Vancouver Island) into northern California in outer Coast Ranges and the Sierra Nevada foothills (lower forest belt). Also disjunctly in the Rocky Mountains of southeastern British Columbia, far western Washington, northern (panhandle portion of) Idaho and northwestern Montana. The species' general distribution is mapped in Little (1971) and Krajina et al. (1982).

ELEMENT_GLOBAL.2.157732