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Frangula spp.

false-buckthorns

Rhamnaceae

Europe, North Africa, western Asia, and the Americas

Attracts Pollinators Attracts Butterflies

Native to North America

SunFull Sun – Part Shade

WaterMedium

HardinessZones 4–9

Overview

Frangula spp. is a genus of about 50 deciduous and evergreen shrubs and small trees in the buckthorn family (Rhamnaceae), separated from Rhamnus spp. by their thornless twigs, alternate leaves, and flowers with five petals. Plants reach 6-30 feet (2-9 m) tall depending on the species, with smooth grey bark and glossy oval leaves marked by neat, parallel veins. The small greenish-yellow flowers are 0.1-0.2 inch (3-5 mm) across and inconspicuous, opening in late spring and summer, and they are followed by pea-sized berries that ripen from green through red to black. Birds eat the fruit and scatter the seed, and one species, the glossy buckthorn F. alnus, has become an aggressive invasive in wetlands and woodlands of northeastern North America. Other species, such as the western coffeeberry F. californica and cascara F. purshiana, are grown as native landscape and habitat plants. The bark and unripe fruit contain anthraquinone compounds that act as a strong laxative and cause stomach upset if eaten.

Native Range

Frangula spp. occurs across Europe, North Africa, and western Asia, and through the Americas from Canada to South America. North American species include the western coffeeberry F. californica, cascara F. purshiana, and Carolina buckthorn F. caroliniana.

Suggested Uses

Used as informal hedges, woodland-edge and wildlife shrubs, and screening in native and habitat plantings, spaced 4-8 feet (1.2-2.4 m) apart. The native coffeeberry and cascara are grown for their berries and bird value. The European glossy buckthorn is excluded from plantings in regions where it is invasive.

How to Identify

Recognized by thornless twigs, alternate oval leaves with 6-12 pairs of straight, parallel side veins, and clusters of tiny greenish-yellow five-petalled flowers in the leaf axils. The pea-sized berries ripen from red to black, often with several colours present at once. The lack of spines separates Frangula spp. from the true buckthorns (Rhamnus spp.).

Appearance

Size & Dimensions

Height6' - 30'

Width/Spread6' - 15'

Reaches mature size in approximately 5 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~6 weeks

Spring Summer

The small greenish flowers open over a long season from late spring into summer, roughly May to July, rather than in a single flush. Bees work the flowers steadily. The fruit colours from green through red to black over late summer and autumn.

Detailed Descriptions

Foliage Description

glossy green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-8 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.5(Neutral)

357912

Soil Types

loam sand clay

Drainageaverage

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

3-5 years to flowering size

Care & Maintenance

Care Guide

Grow Frangula spp. in full sun to part shade in most soils, from moist or wet ground for F. alnus to dry, lean slopes for F. californica, across a pH of about 5.5-7.5. Once established, plants need little attention and tolerate pruning, poor soils, and a range of moisture. Water new plants through their first seasons until rooted. Where the glossy buckthorn F. alnus is grown, bird-sown seedlings spread into wild ground, and it is regulated or banned in several US states and Canadian provinces. A spring mulch conserves moisture for the moisture-loving species.

Pruning

Prune in late winter while dormant to shape the plant, thin crowded stems, or limit size; the shrubs resprout readily from cut stems. Removing fruit before it ripens reduces unwanted seedlings from the weedy species. Overgrown plants tolerate hard renewal pruning.