This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
[Capsella Medic. Pfl. Gatt. 1: 85. 1792.]
Annual or winter-annual erect herbs, pubescent with forked hairs; basal leaves tufted. Flowers racemose, small, white. Silicles cuneate, obcordate or triangular, compressed at right angles with the septum, the valves boat-shaped, keeled. Style short. Seeds numerous, marginless; cotyledons accumbent. [Middle Latin, purse, from the shape of the pod.]
About 4 species, natives of the northern hemisphere, the following typical. In addition to the following, another occurs in the western parts of North America.
Thlapsi Bursa-pastoris L. Sp. Pl. 647. 1753. B. past oris Weber in Wigg. Prim. Fl. Hoist. 47. 1780. Capsella Bursa-pastoris Medic. Pfl. Gatt. 1: 85. 1792. Bursa Bursa-pastoris Britton, Mem. Torr. Club 5: 172. 1894.
Erect, branching, 6-20' high from a long deep root, pubescent below, mainly glabrous above. Basal leaves more or less lobed or pinnatifid, forming a large rosette, rarely entire, 2'-5' long; stem-leaves few, lanceolate, auricled dentate or entire, flowers white, about 1" long; pedicels slender, spreading or ascending, $"-7" long in fruit; pods triangular, cuneate at the base, truncate or emarginate at the apex, 2"-4" long; seeds 10 or 12 in each cell.
In fields and waste places, very common. Naturalized from Europe, and widely distributed as a weed over all parts of the globe. Consists of several races. Jan.-Dec. Other names are St. James'-weed, case-weed, mother's heart. Pick-purse. Pick-pocket. Lady's-purse. Witches'-pouches. Shovel-weed. Wind-flower. Pepper-plant. Toothwort. Toywort.