This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Unlike flax, which is equally a weed of cultivation, Shepherd's Purse is not known in any early seed-bearing deposits. It is distributed throughout all Temperate and Arctic Europe, North Africa, and Asia to the Himalayas, and has become introduced into all temperate countries. This ubiquitous variable weed is found in every vice-county in Great Britain, and ascends to 1200 ft. in some parts.
Essentially a weed of waste places, Shepherd's Purse is a familiar sight wherever we turn on all ground which is not grass-grown, along our highways, in the farmyard, on waste heaps, in gardens, stableyards, and in the cornfield, or generally where open soil allows it to take a hold: and when it does so it comes up freely, flowering all the year round and forming abundant seed. To the farmer it is a pest, to the botanist an instance of mutations of great interest.
Photo. H. Hanley - Shepherd's Purse (Capsella Bursa-pastoris, Medic.)
The Shepherd's Purse has the rosette habit, the leaves lying flat on the ground, in a circle around the base of the stem, which is more or less leafless above. The root is long, tapering. The plant is extremely variable in the form of the leaves as well as in the shape and size of the pods. The stems are branched. The radical leaves are deeply divided nearly to the base, or they may be undivided, lance-shaped. The terminal lobe is often triangular. The upper leaves are clasping, auricled.
The flowers are white, or reddish-tinged in winter, like many other plants, e.g. White Deadnettle. The flower-stalks are slender. The sepals are spreading and equal. The pods are triangular, inversely heart-shaped, wedge-shaped, or rounded. The stigma is not stalked. The style is short. The valves are smooth. The seeds are numerous, oblong, clotted, very small. The pod has no wings, as in Thlaspi, in which the plant was once placed. The radical leaves as well as the pods are extremely variable.
This plant is often 2 ft. high, usually 1 ft. It is in flower all the year, and is a herbaceous annual, propagated by seeds.
The anthers and stigma are mature at the same time. The flowers are small and inconspicuous. Honey is secreted in 4 nectaries at the side of the short stamens. The longer stamens are of the same length as the style. Hence, as would be expected, the plant is usually self-pollinated. Female flowers have been found as well as complete (lowers, both on the same and on different plants. In the earlier flowers the stamens have been found to be incomplete, so that the above unusual conditions may be due to the variation in the thermal constant.
The visitors are Diptera, Syrphidae, Eristalis nemorum, Syrphus balteatus, Syritta pipiens, Ascia podagrica, Melithreptus script us, M. taeniatus, M. pictus, Muscidae, Anthomyia.
The plant is dispersed by its own agency. The pods are not winged and contain many seeds, and open and allow them to fall out around the parent plant.
Shepherd's Purse requires a sand soil, and is a sand-loving plant.
The fungus, Cystopus candidus, distorts the branches, and covers them with a white crust, and Peronospora parasitica also infests it. The Bath White Butterfly (Pieris daplidice), Arctia caja (Tiger Moth), Lepidoptera, and the Hemiptera Aphis brassicae, A. papaveris, Siphono-phora pisi are amongst those that feed on it.
Capsella is Latin for a little box or capsule, referring to the pods. Bursa-pastoris is Latin for Shepherd's Purse, also in allusion to the pods.
This ubiquitous plant is called Bad Man's Oatmeal, Blind-weed, Case-weed, Clappede Pouch, Cocowort, Fat Hen, Lady's Purse, Mother's Heart, Naughty Man's Plaything, Pepper-and-Salt, Pick Pocket, Pick Purse, Pick-your-Mother's-heart-out, Poor Man's Parmcetty, Sanguinary, Shepherd's Bag, Shepherd's Pouch, Shepherd's Scrip, Tooth-wort, Toywort, Ward-seed, Witches' Pouches. Pick Purse, etc., is given in allusion to the poorness of land. It was called Sanguinary because supposed to stanch a bleeding nose. Shepherd's Pouch alludes to the shape of the seed-vessel, as does Shepherd's Purse.
In the Eastern Border children play a game with the seed-pouch, one holding it out to a companion and telling him to take hold of it. It cracks, and the other triumphantly says, "You've broken your Mother's heart". The seeds are collected, and are given to birds.
Essential Specific Characters:35. Capsella Bursa-pastoris, Medic. - Stem erect, branched above, lower leaves pinnatifid, lanceolate, dentate, upper auricled, oblong, or sagittate at the base, flowers small, white, pouch triangular, obcordate, 2-valved, variable.