Pentanema squarrosum (Ploughman's-spikenard)

Pentanema spp.

Attracts Pollinators Attracts Butterflies Deer Resistant Drought Tolerant Container Friendly

HardinessZones 4–9

Overview

Pentanema spp. is a genus of about 60 to 80 herbaceous perennials and subshrubs in the daisy family, recently segregated from Inula spp. and distributed across Europe, Africa, and Asia. Plants form clumps of upright stems 8-32 inches (20-80 cm) tall, clothed in narrow to lance-shaped leaves that are often hairy and aromatic when bruised. From early to late summer the stems carry yellow daisy-like flower heads 1-2.5 inches (2.5-6 cm) across, each with many slender ray florets surrounding a darker yellow disk. Several species, including P. ensifolium and P. orientale, were long grown in gardens under the name Inula spp. for their long summer display and compact habit. The genus generally grows in full sun on well-drained soil in meadows, rocky slopes, and open scrub, and most species tolerate lean conditions once established. Spreading habits vary across the genus from tight clumps to slowly creeping colonies. Flower heads draw bees, butterflies, and hoverflies, and the dry seed heads persist into autumn. Some species can self-seed where conditions suit. Foliage and roots of several species have a long history of folk medicinal use.

Native Range

Pentanema spp. is native across the temperate and subtropical Old World, spanning Europe, the Mediterranean, Africa, and much of Asia from the Caucasus to the Himalaya and China. Species grow in meadows, on rocky slopes, in open woodland, and in dry scrub.

Suggested Uses

Pentanema spp. is planted in sunny borders, gravel and meadow gardens, and pollinator plantings for its summer daisies. Lower, compact species suit the front of borders and rock gardens, while taller ones fill mid-border positions.

How to Identify

Look for clumps of upright, leafy stems bearing yellow daisy flower heads with many narrow ray florets around a yellow disk. Leaves are narrow to lance-shaped, often softly hairy and faintly aromatic when crushed. The summer bloom and ray-and-disk heads place it among the daisies once grouped under Inula spp..

Appearance

Size & Dimensions

Height8" - 2'8"

Width/Spread1' - 2'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~8 weeks

Summer

Flowering runs through summer, roughly June through September depending on species and climate. The yellow daisy heads open over several weeks and are followed by tufted seed heads that hold into autumn. Bees, butterflies, and hoverflies visit the open flowers.

Detailed Descriptions

Foliage Description

green to gray-green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 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 Range6.0 - 7.8(Neutral)

357912

Soil Types

loam sand rocky chalk

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

1-2 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Pentanema spp. grows in full sun on moderately fertile, well-drained soil and tolerates lean, dry ground once established. The genus needs good drainage and can rot in wet winter soils, though it withstands summer heat and short droughts. Most species are cold-hardy through temperate winters and return from the rootstock each spring. Lift and divide congested clumps every few years to renew growth. Plants may self-seed, so removing spent heads limits unwanted seedlings. Few serious pests affect the genus, though powdery mildew can appear in humid, crowded plantings.

Pruning

Cut stems back to the base after flowering or in late winter before new growth begins. Removing faded flower heads through summer extends the display and limits self-seeding. Divide clumps in spring to renew older plants.