This section is from the book "How To Know The Wild Flowers", by Frances Theodora (William Starr Dana). Also available from Amazon: How To Know The Wild Flowers.
Stem. - Low, branching. Root-leaves. - Clustered, incised or toothed. Stem-leaves. - Arrow-shaped, set close to the stem. Flowers. - White, small, in general structure resembling other members of the Mustard family. Pod. - Triangular, heart-shaped.
This is one of the commonest of our wayside weeds, working its way everywhere with such persistency and appropriating other people's property so shamelessly, that it has won for itself the nickname of pickpocket. Its popular title arose from the shape of its little seed-pods.
 
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