Garden News Blog

Weed of the Month: Shepherd’s Purse

By Saara Nafici | May 22, 2015

Vacant lots, fields, and tree beds around Brooklyn are filled with shepherd’s purse (Capsella bursa-pastoris) right now. This prolific springtime weed has petite white flowers, and it’s common name refers to the nearly heart-shaped seedpods that form on its long stalks. They resemble the little leather pouches carried (at one time) by shepherds in Europe and Asia Minor, from whence the plant originated.

Shepherd’s purse spread across the globe with European colonization and is now one of the most common weeds in the world. In my own travels, I have seen it growing across the U.S., as well as in France, Iran, Turkey, and Canada!

Like other members of the mustard family, shepherd’s purse reproduces via abundant, long-viable seeds that burst out of the pods, and many generations can be produced within a single year. The leaves grow in a rosette and are edible in the early spring, much like dandelion or chicory greens. The seedpods add a peppery punch to stir fries and salads—they’re also a common ingredient in traditional Chinese cuisine. Historically, the vitamin K–rich plant was used for all manner of internal and external blood regulation. It’s been used to treat everything from nosebleeds to hemorrhages to menstrual problems. German soldiers during World War II relied on shepherd’s purse extract to treat wounds in the field when other medicines were scarce.

As I was poking around my weed reference books, reading up on the usual statistics like plant distribution and reproduction, I learned for the first time about an unusual adaptation exhibited by shepherd’s purse: myxospermy. When moistened in the soil, its seed exudes a sweet, mucilaginous substance that entraps and then digests small insects and microorganisms. As the seed germinates, the nutrients from the insects feed the seedling, making shepherd’s purse a “protocarnivorous” plant.

This is surprising. Most true carnivorous plants, like Venus flytraps and pitcher plants, live in nutrient-poor bogs and evolved to ingest insects to supplement their nutrient intake. But shepherd’s purse grows in fields, gardens, vacant lots—all the usual environments where weeds thrive. Scientists are puzzling over why this would be—does this adaptation hint at a long-ago trauma in the plant’s evolutionary history? Perhaps one day the mystery will be solved, but in the meantime, I’ll never look at shepherd’s purse in the tree pit in front of my building the same way.

Plant ID: What is this weed looking thing?

I’m fairly sure this is indeed Field Pennycress – the notch in the circular seed pod is a field mark. In my region, Shepherd’s Purse has a heart-shaped seed pod that’s smaller. There are several other related small mustards, but I’m fairly confident with that ID – and to my knowledge, all mustards are edible (if not all good tasting) – though I’m happy to be corrected on that.
I like this plant. It loves disturbed soil, and if it’s present, even if you mulch, you’ll get a bit here and there. The leaves before it goes to seed have a nutty/mustardy taste in salads which I quite like. That taste gets stronger when they go to seed, but in my opinion is still okay. I’m sure you can use it as a cooked green, and can probably eat the tenderest part of the stem when it’s growing quickly either raw or steamed. Flowerheads taste good to me too – though a bit strong flavoured. I’ve had people taste this and love it, and read descriptions that say it tastes awful. Try a small bit to make sure you like it.
In good conditions (full sun, various soil types) it gets very big, and produces many seed pods. In the past, I’ve gathered a bunch of big plants and hung them to dry, then gathered the seeds out of them. When ground, the dried seeds make a very nice seasoning a bit like black pepper (Pennycress is closely related to Peppergrass, as well as Shepherd’s Purse). There’s likely not much need to replant seed – it’ll be back!
Of course – make sure you’re confident with the ID yourself before consuming it.

Capsella bursa-pastoris was limited to wetter areas and field edges when tillage was common.

However, reduced tillage created new opportunities for the winter annual weed, which is more commonly known as shepherd’s purse.

Along with narrow-leaved hawk’s beard, cleavers, flixweed and stinkweed, this member of the mustard family appears early in spring to rob fields of water and nutrients.

Fall herbicide programs can help control it, but like stinkweed, it can be tough to control in spring. The recent trend to shallow, vertical tillage has provided some control.

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The weed is also known as shepherd’s pouch, St. James weed, pepper plant, mother’s heart, poor man’s parmacettie, sanguinary, shepherd’s heart and capsella.

It has joined the ranks of weeds that have developed resistance to Group 2 herbicides in Saskatchewan and Alberta.

Cotyledons are oval and have rounded tips when it is a seedling. The first leaves are lobed, and the leaves are covered in star-shaped hairs.

The immature plant’s leaf margins are highly variable, making identification tricky. They can be shallowly lobed or deeply cut.

The stems are sparsely branched and covered with star-shaped hairs. The stem leaves alternate. Balsal lobes of the leaves are pointed and clasp at the stem.

The weed grows up to 90 centimetres when not controlled and sprouts from a rosette at the ground. Mature plants have white flowers with four petals.

Flat pods form with a notched top and a small beak and each contains about 20 seeds.

Plants produce 45,000 seeds each. It begins flowering early and continue to produce seed throughout the season if allowed to reach maturity.

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Seeds are orange, oblong and have a pitted surface.

Broadleaf herbicides are available that can control it in spring crops, but it needs full rates and early treatment to fully stop the pest. Bromoxynil with MCPA and clopyralid with MCPA can be effective.

Both work in cereals and flax and there is a minor use expansion of Curtail (clopyralid) for canaryseed. As well, Buctril (Mextrol, Badge and Logic) is also registered for canaryseed.

The weed can run amok in non-herbicide tolerant broadleaf crops.

In-crop applications of Odyssey and imazethapyr are effective in peas.

Glyphosate is effective in post harvest and pre-seeding applications.

The weed is found in most areas of the Prairies with the highest populations in the canola belt.

However, fewer instances of shepherd’s purse are seen in the brown soil zone and Manitoba’s southern Interlake and Red River valley regions.

Some herbal remedies are created using the weed and its seed, but it contains glucosinolates, which can be hard on the digestive tract.

Shepherd’s Purse is originally from Europe, but has become very common in many parts of the world. The species name bursa-pastoris mean purse of the shepherd. This name refers to the fruit-capsule in the shape of a triangle, attached to slender stalk from its pointy end, with a notch on the top. Shepherd’s Purse grows in gardens, fields, waste grounds, and embankments with soils that are not too dry and that provide enough sunshine. This is rather a small plant, growing to 6-20 cm high. The basal leaves are lanceolate and dentate. The white flowers are arranged in loose racemes. Flowers are radially symmetrical with four petals. The seeds of this plant give off a viscous compound when moistened. Aquatic insects stick to it and eventually die. This can be used as a mosquito control method, killing off the mosquito larvae, and makes it a borderline carnivorous plant. The seeds, leaves, and root of this plant are edible. In China, it is commercially grown for consumption. Flowering: December-January.
Medicinal uses: In Manipur, it has been used to stop bleeding from internal organs.

Shepherd’s purse – Capsella bursa-pastoris

Shepherd’s purse

Capsella bursa-pastoris (L.) Medicus
Brassicaceae (Mustard family)

Life cycle

Erect winter or summer annual.

Leaves

Leaves initially develop from a basal rosette. Basal leaves are stalked and highly variable in shape; young leaves are first roundedand elongated, becoming variously lobed, toothed to wavy. Smaller stem leaves are alternate with smooth to toothed margins andclasping bases.

Stems

Erect, slender, hairy, up to 2-foot-tall stems bolt from a basal rosette to flower. Flower stems are usually unbranched with few to no leaves.

Flowers and fruit

White flowers with four small petals are found in terminal clusters. Fruit are distinctly heart-shaped to triangular pods found on elongated, unbranched stems.

Reproduction

Seeds.

Shepherd’s purse rosetteShepherd’s purse seedheadShepherd’s purse fruit

Plant & Pest Diagnostics

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Used by 17th century apothecary and herbalist, Nicholas Culpeper, who recommended that ‘the juice being dropped into the ears, heals the pains, noise and mutterings thereof’.

Shepherd’s-purse appears in the poetry of Robert Louis Stevenson (1850-1894). From ‘The Flowers’

‘All the names I know from nurse:
Gardener’s garters, Shepherd’s purse,
Bachelor’s buttons, Lady’s smock,
And the Lady Hollyhock.

Fairy places, fairy things,
Fairy woods where the wild bee wings,
Tiny trees for tiny dames –
These must all be fairy names!’

And in the poetry of John Clare (1793 -1864). From ‘The Flitting’

‘Een here my simple feelings nurse
A love for every simple weed,
And een this little shepherd’s purse
Grieves me to cut it up; indeed
I feel at times a love and joy
For every weed and every thing,
A feeling kindred from a boy,
A feeling brought with every Spring.
And why? this shepherd’s purse that grows
In this strange spot, in days gone bye
Grew in the little garden rows
Of my old home now left; and I
Feel what I never felt before,
This weed an ancient neighbour here,
And though I own the spot no more
Its every trifle makes it dear.’

Shepherd’s purse

Botanical name: Capsella bursa-pastoris
Family name: Brassicaceae

Shepherd’s purse is a fairly small annual weed which can germinate at most times of the year and is very commonly found in crops and gardens throughout New Zealand. It is often found in winter because of its ability to grow throughout the year, and so it can grow readily at times of the year when more competitive summer annuals are absent. It is usually present at other times of the year too, but just might not be quite as noticeable. Shepherd’s purse can complete its life cycle quickly, so can undergo several generations within one year. It has long-lived seed, lasting in the soil several decades under some conditions, so this coupled with the rapid life cycle means there can be quite a build-up of seed in the soil.

Distinguishing features

It starts as a rosette, with very variable leaf shapes which can make it difficult to identify at times while vegetative. For example, it could be easily confused with the rosette of hawksbeard, though the leaf shape is slightly different. Likewise a Cape weed rosette looks similar, though Cape weed usually has a larger rosette and is whitish under the leaf. However, shepherd’s purse often soon puts up a flower stem with small white flowers, then forms lots of its characteristic heart-shaped seed pods, which are evidently similar in shape to the purses that shepherds carried around back in ancient history, hence the name. Although the rosettes seldom get much bigger than 10-15 cm diameter, the stems can often get up to 20-30 cm tall if growing conditions are good.

Control

It tolerates quite a few different herbicides, being quite resistant to many selective herbicides such as dicamba, clopyralid, picloram and trifluralin, making it very difficult to control in forage brassicas. However, the herbicide clomazone (sold in products such as Director CS and Ombre Encaps) will control it in brassica crops if applied at pre-emergence. It is well controlled by MCPA and 2,4-D, and most crops other than the brassicas have a number of herbicides that can be used to control it. Non-selective herbicides such as glyphosate and amitrole easily kill it, as does cultivation.

Shepherd’s Purse

Shepherd’s purse (Capsella bursa-pastoris) and several similar wild mustard cousins grow as cool-season annuals throughout North America. Seedlings are hardy to 0 degrees F, and often begin flowering at a young age. Triangular seedpods quickly develop. Left uncontrolled, one plant may shed 40,000 seeds. Young plants are easy to pull from moist soil, and they make good compost fodder, provided they are not holding mature seeds. They also can be cultivated into submission with a sharp hoe.

Weed Control Techniques

Pulling. Most young weeds can be pulled from the soil. They will slide out most easily if you pull them when the soil is wet. Getting the root up is crucial, so think of the main stem as the root’s handle, and grasp it as close to the soil line as you can. If you find that the weeds are breaking off at the crown as you pull, slip a kitchen fork, dandelion weeder, or similar tool under the weed, and pry and twist as you pull it up. Weeds that have taproots, such as dandelion and plantain, usually must be pried out. A flexible pair of waterproof gloves will keep your hands comfortable as you weed, and it’s good to have a nice sitting pad, too. Let pulled weeds bake in the sun for a day or so before composting them. If pulled weeds are holding mature seeds, compost them separately in a hot, moist pile before using this compost in the garden.

Cultivating. Slicing and dicing weeds with a hoe works best when the soil is relatively dry, and the same goes for cultivating with a tiller. With their tops mangled and roots cut, most young weeds will quickly shrivel up and die. Be careful to cultivate only the top inch or two of soil or you may injure nearby garden plant roots and drag new weed seeds to the surface. A sharp hoe works much better than a dull one, so refresh the edge on your hoe with a steel file between weeding sessions. After using either a hoe or tiller to cultivate weeds, go back the next day to nip out any survivors. When battling perennial weeds, you can weaken the plants by chopping them down with a sharp hoe, but it’s best to combine hoeing with digging to achieve good control. Never use a tiller in soil that is infested with bindweed, quackgrass, or other weeds that regrow from small pieces of root; they are easily spread by rototilling.

Photo courtesy of Jenna Antonino DiMare, National Gardening Association

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