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Rhamnus spp.

buckthorns

Rhamnaceae

Northern Hemisphere: Europe, Asia, North America

Attracts Pollinators Deer Resistant Drought Tolerant

Native to North America

SunFull Sun – Part Shade – Full Shade

WaterLow · drought-tolerant

HardinessZones 3–9

Overview

Rhamnus spp. is a genus of about 110 species of deciduous and evergreen shrubs and small trees in the family Rhamnaceae, distributed across the Northern Hemisphere and into parts of Africa and South America. Plants range from low shrubs 3 feet (90 cm) tall to small trees of 20 to 30 feet (6 to 9 m), with simple, often glossy leaves marked by prominent parallel veins. Branch tips of several species end in a short spine, the source of the name buckthorn. The small greenish to yellowish flowers are inconspicuous, opening in spring, and are followed by rounded berry-like drupes that ripen from red to black and each hold two to four seeds. The fruit of many species contains compounds with a strong laxative effect and is mildly toxic to people if eaten. The genus grows in woodland, hedgerows, scrub, and along watercourses on a wide range of soils. A limitation is that several species, including R. cathartica, are listed as invasive across much of North America, where birds spread the seed and the plants form dense thickets that crowd out native vegetation.

Native Range

Rhamnus spp. is native across the Northern Hemisphere, through Europe, Asia, and North America, with additional species in Africa and South America. Species grow in woodland, scrub, hedgerows, and streamside thickets, and R. cathartica of Eurasia has naturalized widely in North America.

Suggested Uses

Evergreen Rhamnus spp. species such as R. alaternus are used as hedges, screens, and clipped specimens in mild climates. Native species are grown in wildlife and woodland plantings, where the fruit supports birds, while invasive species are avoided in regions where they spread.

How to Identify

Identify Rhamnus spp. by its simple leaves with prominent, curving parallel veins, its short spine-tipped branchlets in many species, and its clusters of small greenish flowers. The rounded drupes ripen from green through red to glossy black and contain two to four hard seeds. The spine-tipped twigs and the curved leaf veins separate Rhamnus spp. from the closely related thornless Frangula spp..

Appearance

Size & Dimensions

Height3' - 30'

Width/Spread5' - 20'

Colors

Flower Colors

green

yellow

Foliage Colors

green

Bloom Information

Bloom Period

~4 weeks

Spring

Rhamnus spp. flowers in spring, roughly April through June, with small greenish to yellow flowers clustered along the twigs that are easy to overlook. Many species carry male and female flowers on separate plants. The fruit ripens through summer and autumn from red to black and is taken by birds.

Detailed Descriptions

Foliage Description

green to dark green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade SunFull Shade

Requires 3-12 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 - 8.0(Neutral)

357912

Soil Types

clay loam sand chalk

Drainageaverage

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

5-10 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Across the genus, Rhamnus spp. grows in full sun to part shade on a wide range of soils, from dry to moist and acidic to alkaline, with a soil pH of about 5.5 to 8.0. Established plants tolerate drought, poor soil, and shade, which contributes to the invasive spread of some species. Plants are grown from seed or cuttings, and the evergreen species are used for hedging in mild climates. Where R. cathartica and similar species are invasive, native or non-spreading species are chosen instead. Birds disperse the seed widely, so self-sown seedlings often appear near established plants.

Pruning

Plants tolerate pruning and shearing and are cut back in late winter to shape hedges or limit size. Evergreen species respond well to clipping during the growing season. Removing the fruit before it ripens reduces self-seeding from species that spread by bird-sown seed.