Monday, December 21, 2015

Shepherd's purse

I love the design of this plant.

Capsella bursa-pastoris, known by its common name shepherd's purse because of its triangular, purse-like pods, is a small, annual and ruderal (first to colonize disturbed lands) species. It is a member of the Brassicaceae or mustard family. It is native to Eastern Europe and Asia Minor that is Turkey. It is also naturalized and considered a common weed in many parts of the world such as Britain, North America, China and also in the Mediterranean and North Africa.

C. bursa-pastoris is used as a model organism due to the variety of genes expressed throughout its life cycle. Wikipedia informs us that a model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms.

Unlike most flowering plants, it flowers almost all year round. Like many other annual ruderals C. bursa-pastoris reproduces entirely from seed, has a long soil seed bank and short generation time. It is capable of producing several generations each year.

I found the one I photograph in Montreal, along a sidewalk, as I was walking to a store.

C. bursa-pastoris plants grow from a rosette of lobed leaves at the base.

From the base emerges a stem about 20 to 50 cm tall, which bears a few pointed leaves. The flowers are white and small, in loose racemes, and produce seed pods which are heart-shaped.

Like a number of other plants in several plant families, its seeds contain a substance known as mucilage. The fact that mucilage becomes sticky when wet has led to the thought that perhaps C. bursa-pastoris traps insects which then provide nutrients to the seedling, which would quite interestingly make it proto carnivorous.

Johann Georg Sturm (Painter: Jacob Sturm) - Figure from Deutschlands Flora in Abbildungen at


Capsella bursa-pastoris is a lovely familiar plant of mine that I enjoy seeing very much.


  1. Hi Beste - that mustardy flavour is so delicious ... we've lost the art of eating 'beneficial weeds' - yet it's probably very similar to mustard and cress - the child's seeds to watch grow. Interesting to read about - cheers and have a Merry Christmas and happy New Year - Hilary

  2. So lovely! I had no idea this was called shepherd's purse. What about the other plant along the sidewalks, the one that looks like dill gone to seed?