Wild Flowers of Pittsburgh

Field Pennycress (Thlaspi arvense)

An unimposing little weed, but it delights children by producing round, flat seedpods that look like coins. This one grew in a meadow near Cranberry, where it was blooming and already seeding in the middle of June.

Gray describes the genus and the species:

THLASPI [Tourn.] L. PENNY CRESS
Pod orbicular, obovate, or obcordate, flattened contrary to the narrow partition, the midrib or keel of the boat-shaped valves extended into a wing. Seeds 2-8 in each cell. Cotyledons accumbent. Petals equal.—Low plants, with root-leaves undivided, stem-leaves arrow-shaped and clasping, and small white or purplish flowers. (Name from thlaein, to crush, from the flattened pod.)

T. arvense L. (FIELD P. or MITHRIDATE MUSTARD.) Smooth annual; lower leaves wing-petioled, the upper sagittate-clasping; broadly winged pod 1.2 cm. in diameter, deeply notched at top; style minute. Waste places; not common, except along our northern borders, where too abundant and called “FRENCHWEED.” (Nat. from Eu.)

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One response

  1. Joanne Khew

    Dear Sir,

    We are presently writing a book about phytoremediation in Singapore for public services and non-profit educational purposes, and would like to seek permission to use this picture in our book.

    These materials will appear as originally published in the following book (presently being prepared for publication):

    The Periodic Table of Plants
    Published by Nanyang Technological University

    If you are the copyright holder, may I have your permission to use the above materials in this book? I will use the appropriate citations to acknowledge your publication.

    Thank you for your consideration. I look forward to hearing from you.

    Yours sincerely,

    Joanne Khew on behalf of

    Dr. Tan Swee Ngin
    Assistant Professor,
    Nanyang Technological University. Singapore.

    October 31, 2010 at 11:32 pm

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