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Cynoglossum officinale

hound's-tongue

Boraginaceae Europe and temperate Asia

Attracts Pollinators Deer Resistant Drought Tolerant

SunFull Sun – Part Shade

WaterLow · drought-tolerant

HardinessZones 4–8

Overview

Cynoglossum officinale is a biennial in the borage family, forming a basal rosette in its first year and an erect, branched flowering stem 1-4 feet (30-120 cm) tall in its second. The whole plant is covered in soft grey-green hairs, giving the lance-shaped leaves a flannel-like feel; the largest basal leaves reach 12 inches (30 cm) long. From late spring into summer, coiled clusters at the stem tips uncoil to open funnel-shaped flowers 0.3-0.4 inch (8-10 mm) across, dull reddish-purple to maroon with five rounded lobes. Each flower yields four flattened, teardrop-shaped nutlets covered in barbed prickles that cling to fur and clothing, spreading the seed. Crushed foliage gives off a scent likened to mice. All parts contain pyrrolizidine alkaloids that damage the liver of grazing animals and cause chronic poisoning in cattle and horses. The plant grows on disturbed ground, pastures, roadsides, and rangeland, and it is listed as a noxious weed across much of western North America. It tolerates poor, dry soils but is short-lived, dying after it sets seed.

Native Range

Native to Europe and temperate Asia, where it grows in grassland, scrub, and disturbed ground. It has naturalised widely in North America and is listed as a noxious weed in many western states and Canadian provinces.

Suggested Uses

Rarely planted by choice, it appears mainly as a weed of pasture and waste ground rather than a garden subject. Where it is grown for its historical use in herbal preparations, it is kept in contained beds away from livestock. Its flowers draw bees during the short bloom season.

How to Identify

Identify by the soft, grey, densely hairy lance-shaped leaves and the dull reddish-purple, funnel-shaped flowers borne in coiled clusters that unroll as they open. The barbed, teardrop-shaped nutlets that cling to fur and clothing are diagnostic once seed sets. A mouse-like smell from bruised foliage further marks the plant.

Appearance

Size & Dimensions

Height1' - 4'

Width/Spread1' - 2'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~6 weeks

Spring Summer

Dull reddish-purple flowers open from late spring through summer, the curled flower clusters straightening as the lower buds open first. Flowering continues for several weeks on a branched stem. Barbed nutlets ripen and detach from midsummer onward.

Detailed Descriptions

Foliage Description

grey-green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-10 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 Range6.0 - 8.0(Neutral)

357912

Soil Types

sand loam chalk rocky

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

Flowers in second year from seed

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Performs in full sun to part shade on dry to moderately moist, free-draining soil at a pH from 6.0 to 8.0, including poor, sandy, gravelly, or chalky ground. As a biennial it forms a rosette the first year, flowers and seeds the second, then dies. Established plants tolerate drought and neglect, which contributes to their spread on disturbed land. All parts are toxic to livestock, limiting any use near grazing animals. The barbed seeds spread readily on animals and equipment, so it escapes cultivation easily. It needs no winter protection in zones 4 to 8.

Pruning

No pruning is needed for the plant itself. Cutting or pulling stems before the nutlets ripen prevents the clinging seeds from spreading. Removing the basal rosette in the first year stops flowering the following season.