University of Missouri Extension

IPM1007, Revised November 2009

Practical Weed Science for the Field Scout: Corn and Soybean

Smartweed, Pennsylvania (Polygonum pensylvanicum)

Summer annual broadleaf

Pennsylvania smartweed Pennsylvania smartweed
 

Pennsylvania smartweedA summer annual of horticultural, agronomic, and nursery crops that may reach 3-1/2 feet in height. Seedlings have cotyledons that are lanceolate in outline, with hairs along the margins. Mature plants have leaves that are arranged alternately along the stem and are also lanceolate in outline. Older leaves are usually only slightly hairy and often, but not always, have a purple spot in the middle of the leaf. Stems are branched, often reddish in color and swollen at the nodes. A thin membranous sheath called an ocrea encircles the stem at the base of each leaf petiole. Pink or white flowers are clustered in terminal spikes at the ends of stems.

Pennsylvania smartweed
 

IPM1007, revised November 2009

Wild thing
 

IPM1007 Practical Weed Science for the Field Scout: Corn and Soybean | University of Missouri Extension

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