Shepherd's Purse

Last Thursday, we began a new season of IPM crop scouting at the BCCAC.  One of the weeds we identified during our session was Shepard's Purse (Capsella bursa-pastoris). Shepherd's purse is a winter annual or biennial plant that reproduces by seed and is a member of the Mustard family. 

Three major characteristics separate the mustard family from all other plant families:

1. The stamens are tetradynamous, meaning there are four long stamens and two short stamens in each flower (six in total).
2. Each flower bears four petals that form a cross, hence the alternate family name“Cruciferae,” from the Latin cruciform which means “cross-shaped.”
3. The seed pods each have a thin, translucent inner membrane, the replum, that separates the two chambers of the pod, and to which the seeds are attached

 A plant must have all three characteristics to be a mustard.

Shepherd's Purse consists of a rosette of basal leaves up to 9" across, from which one or more flowering stalks develop that are little branched and up to 2½' tall. The size of a plant varies considerably with the fertility of the soil and availability of moisture.  Flowers on Shepherd's-purse are small and white with 4 petals set in the shape of a cross. They are 1/12 to 1/6" wide and occur in elongated clusters at ends of branches on slender stems. Shepherd's Purse can be a problem in grain crops since it can reduce yields.


History

Shepherd's Purse is a literal translation of the species name, bursa-pastoris, which refers to the shape of the seed pods. The pods resemble the pouches carried by early European peasants. Worn at the waist, these purses were packed with enough food to last the day when shepherds tended their flocks far from home.

In southern Europe and southwestern Asia, shepherd's purse has been prized since ancient times for its medicinal value. A tea made from the dried crushed leaves has long been used to stop internal hemorrhages, especially of the stomach, lungs, uterus, and kidneys. During World War I Shepherd's Purse was used to stop internal hemorrhages.

Control

Shepherd's purse has a slender taproot and can be easily hand-pulled or hoed from moist soil in flower and vegetable gardens while plants are young.

In lawns, post-emergent herbicides provide easier control of Shepherd's purse than pre-emergents. Spot treat by spraying individual plants, rather than applying a weed and feed over the entire lawn. If you would rather not spray, the herbicide can be brushed on instead. Apply the herbicide in mid-spring and again in mid-autumn if a new crop of shepherd's purse emerges.

These herbicides are most effective when temperatures are between 60-80 degrees F. Do not spray if temperatures are projected to exceed 85 degrees within the next 48 hours. Choose a time when no rain is forecast for at least 24 and preferably 48 hours. To avoid herbicide drift, spray only when the air is still. Drift can harm or kill desirable broadleaf plants such as flowers, vegetables, trees and shrubs.

Additional Information

UC - Davis - Weed Gallery

Virginia Tech Weed Gallery Photos of Shepherd's Purse

Flora of China - Capsella bursa-pastoris

Penn State - Shepherd's Purse

PA wildflowers by the month - The Rice Pages

The Mustard Family

Mustard Identification - Washington State University