Pachyphragma macrophyllum (giant spring brassica)

Pachyphragma spp.

Brassicaceae Caucasus and northeastern Turkey

SunPart Shade – Full Shade

HardinessZones 5–8

Overview

Pachyphragma spp. is a small genus in the family Brassicaceae, usually treated as the single species P. macrophyllum, a clump-forming herbaceous perennial of damp deciduous woodland in the Caucasus and northeastern Turkey. The plant spreads by short rhizomes to form low ground cover 8 to 12 inches (20 to 30 cm) tall in leaf, with flowering stems rising to about 16 inches (40 cm). Long-stalked basal leaves are rounded to kidney-shaped, 2 to 5 inches (5 to 13 cm) across, glossy dark green, with shallowly toothed margins, and release a faint garlic scent when bruised. In early spring, before the tree canopy closes, branched heads of small white four-petalled flowers, each about 0.4 inch (10 mm) wide, open above the emerging foliage. Flat, broadly winged seed pods follow. The foliage persists through the growing season and dies back in winter. Pachyphragma spp. grows in moist, humus-rich soil in part to full shade and tolerates heavy clay better than many woodland perennials. It can be slow to settle after planting and may take a season or two before flowering freely. The early bloom and weed-suppressing leaf cover account for its use in shaded plantings.

Native Range

Pachyphragma macrophyllum is native to the western Caucasus and northeastern Turkey, where it grows in moist, shaded deciduous woodland and along stream banks on humus-rich soil.

Suggested Uses

Pachyphragma spp. is grown as ground cover in shaded borders, woodland gardens, and under deciduous trees and shrubs. The early flowers and dense leaf cover fill the gap before later perennials emerge. It is planted on damp banks and in clay soils where many groundcovers fail.

How to Identify

Look for low clumps of long-stalked, rounded to kidney-shaped glossy leaves 2 to 5 inches (5 to 13 cm) wide with shallow teeth that smell faintly of garlic when crushed. In early spring, branched clusters of small white four-petalled flowers rise above the foliage. Flat, broadly winged seed pods and short spreading rhizomes confirm the genus.

Appearance

Size & Dimensions

Height8" - 1'4"

Width/Spread1' - 1'6"

Colors

Flower Colors

white

Foliage Colors

green

Bloom Information

Bloom Period

~3 weeks

Spring

Flowering occurs in early spring, often March to April, ahead of most woodland perennials and before the tree canopy leafs out. The small white cross-shaped flowers form branched heads and draw early bees. Winged seed pods develop over the following weeks.

Detailed Descriptions

Foliage Description

glossy dark green

Growing Conditions

Sun Requirements

SunPartial Shade SunFull Shade

Tolerates up to 4 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 - 7.5(Neutral)

357912

Soil Types

clay loam

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Pachyphragma spp. grows in moist, humus-rich soil in part to full shade, conditions that mirror its native woodland floor. It tolerates clay and seasonal dampness but declines in hot, dry, fully exposed sites. Plants establish slowly and spread by short rhizomes to form a steady ground cover over a few seasons. A mulch of leaf mold conserves moisture and feeds the soil. Once settled, the genus needs little care beyond an occasional clearing of old foliage in late winter.

Pruning

Routine pruning is not required. Old or tattered leaves can be cut away in late winter before the new spring growth and flowers emerge. Spent flower stems may be removed after bloom to keep the clumps tidy or left to set seed.

⚠️ Toxicity Warning

Unknown

Perennial