Common cow-wheat

Melampyrum pratense

In other languages: Hengel (Nederlands) · Mélampyre des prés (Français)

Grows wild in Belgium.

Common cow-wheat is an annual plant of the broomrape family with narrow, opposite leaves and tubular, pale yellow to whitish-yellow flowers, always in pairs in the leaf axils and all facing one way. It is a hemiparasite: it makes its own chlorophyll, but uses its roots to tap water and nutrients from the roots of trees and shrubs such as oak, birch and beech, and of bilberry. You find it in open, acid woodland, along woodland paths, in wooded banks and on heath edges on sandy or loamy soil. In Belgium it is locally fairly common in the Campine and the Ardennes, but rare elsewhere. Bumblebees visit the flowers, ants spread the seeds and the plant is a food plant of the rare heath fritillary.

Updated on 9 October 2026

Light
Sun or partial shade
preferably some sun
Moisture
Dry to normal
no wet feet
Hardiness
Fully hardy
down to -30 °C
Size
0.3 m
tall, 0.2 m wide
Flowering
May–September

Key facts
Height	0.3 m
Native to Belgium	Yes
Flowering	May–September

Identify

How to recognise it

Growth habit: Slender annual of 10–40 cm with a branched stem; the branches usually spread in pairs.
Leaf: Opposite, narrowly lance-shaped to linear, 2–8 cm, untoothed and almost stalkless. The upper bracts sometimes have a few teeth at the base.
Flower: Tubular, two-lipped flowers of 10–18 mm, pale yellow to whitish yellow with a deeper yellow lower lip; the mouth is almost closed. In pairs in the leaf axils, all facing one way. From May to September.
Fruit/Seed: A flattened capsule with 1–4 large, elongated, whitish seeds of 4–5 mm, which look like grains of wheat or ant cocoons.
Roots: A small root system with suckers, by which the plant attaches itself to the roots of its hosts.
Confused with: Field cow-wheat has a dense spike with purplish-red bracts and grows in chalky fields; it is very rare. Yellow rattles are also hemiparasites with yellow flowers, but they grow in grassland and have an inflated calyx. Common cow-wheat: open woods, pale yellow flowers in pairs facing one way.

Flowering: May–September

In your garden

Why grow it?

Long-tongued bumblebees reach nectar deep in the flower tube; shorter-tongued bumblebees sometimes bite a hole in the tube to get at it.
Food plant for the caterpillars of the heath fritillary, a rare butterfly of woodland clearings.
The seeds carry a fatty appendage and are dragged by ants to their nests: that is how the plant spreads.
A characteristic plant of old, acid woods and woodland edges, showing that a spot has seen little fertiliser or disturbance.
A fascinating plant to watch: it lives half on its own and half on the roots of its neighbours.

Common cow-wheat: where does it grow best?

In the wild in open oak and birch woods, beechwoods, along woodland paths, on wooded banks, in clearings and on heath edges with bilberry.
Partial shade or light sun; in deep shade and in full, dry sun it disappears.
Acid, nutrient-poor, humus-rich sandy or loamy soil, moderately dry to moist, with a layer of leaf litter.
In the garden there is a chance only under existing oaks, birches or bilberries on acid, never-fertilised soil, in a natural woodland edge.

Goes well with

Bilberry: A favourite host, on the same acid, humus-rich soil.
Wavy hair-grass: A fine, silvery-green grass of the same acid woodland edges.
Heather: For the transition from woodland edge to heath.
Wood sage: Also flowers in summer in light, acid woodland edges, and is good for bees.
May lily: A small white spring flower of the same acid woods.

Maintenance

Common cow-wheat: when and how to plant it?

Be aware that it is tricky: cow-wheat is annual, needs a host and only germinates from fresh seed. Pot-grown plants hardly exist.
Look for seed at a nursery or seed supplier for native plants. If you can’t find it, never collect seed in nature reserves.
Sow the seed as fresh as possible, in late summer or autumn, just under the leaf litter at the foot of an oak, birch or bilberry. Don’t let the seed dry out.
The seed needs a cold winter and only germinates in late winter or early spring.
Leave the litter in place, don’t dig, don’t feed and don’t water: the plant lives off the soil as it is.
Never dig up plants from the wild: they are attached to the roots of their host and die when dug up.

Care

Water: Not needed. In a normal woodland edge there is enough moisture.
Feeding: Never. Fertiliser and lime drive cow-wheat out and let grass and bramble take over.
Leaf litter: Leave leaves and needles on the ground: that is where the seed germinates and overwinters.
Host: Spare the nearby trees, shrubs and bilberries: without their roots, cow-wheat fades away.
Letting it seed: Let all plants die back and set seed: as an annual it survives only through seed, and that seed is short-lived.

Tip: Only try cow-wheat if you already have acid soil with oak, birch or bilberry, and sow the seed fresh straight into the leaf litter: dried seed hardly germinates.

Pruning and mowing

When: No pruning or mowing is needed: cow-wheat is annual and disappears by itself in autumn.

How:

Leave the plants standing after flowering until they have dropped their seed.
Don’t clear away the dead plants: they rot down by themselves in the litter.
Keep a woodland edge open by cutting out the odd bramble or sapling, so there is enough light.

Caution: Don’t drive or walk over the site in spring: the seedlings are tiny and fragile.

Pruning calendar and basic rules

Propagation

Seed: Sow fresh seed from ripe capsules in July–September straight away under the litter near a host. Dried or old seed hardly germinates.
Ants: In a suitable woodland edge, ants spread the seed by themselves over short distances.

Common cow-wheat: how does it get through the winter?

Hardy to −30 °C.

Cow-wheat is annual: the plants die in autumn.
The seed overwinters in the moist leaf litter and germinates in late winter or early spring.
The seed survives frost well, but not drying out: that is why a layer of litter is so important.

Diseases and pests

Doesn’t germinate: Usually because the seed had dried out or was too old, or because there is no host nearby. Sow fresh seed close to oak, birch or bilberry.
Disappears: Because of too much shade, fertiliser, trampling or raking away the litter. Keep the spot light, poor and undisturbed.
Holes in the flowers: Short-tongued bumblebees bite the flower tube open to steal nectar. This is normal and does the plant no harm.
Overgrown: Bramble, bracken or grass can crowd it out. In a small woodland edge, cut them back now and then.

Through the year

February: The seed germinates under the litter.
March: Tiny seedlings; don’t trample.
May: First pale yellow flowers.
June: Flowering. Bumblebees on the flowers.
July: Flowering. First ripe capsules; ants carry seed away.
August: Flowers and seed. Sow fresh seed straight away.
September: Last flowers. Sow under the litter.
October: The plants die off; leave the litter in place.

You and this species

Did you know?

The name Melampyrum comes from the Greek melas, ‘black’, and pyros, ‘wheat’: seeds of field cow-wheat mixed in with grain turned the bread dark.
The seeds resemble ant cocoons in shape, size and colour. Ants carry them to their nests, eat the fatty appendage and leave the seed itself.
The name cow-wheat also refers to the seeds, which look like grains of wheat.

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