This section is from the book "Harper's Guide To Wild Flowers", by Caroline A. Creevey. Also available from Amazon: Harper's Guide To Wild Flowers.
Family, Parsley. Color, white or sometimes purplish. Of the umbel, the outer flowers are larger than the others, with inversely heart-shaped petals. Both involucre and involucels of green bracts present. Leaves, thrice compound. Leaflets, broad, toothed.
A coarse, rough plant, sometimes 8 feet high, with a rank smell about its foliage. In swamps or wet grounds over nearly the whole country.
 
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