Leaf:  Alternate, simple; blades oval, lanceolate, or elliptical, pointed to round tipped; margins with tiny forward-pointing hairs; both surfaces nearly smooth; upper surface marked with purple to brown spot in center of blade; lower leaves with petioles to 3 cm long.

Flower:  Elongated clusters in shape of a spike (1.25 cm long) at the tip of the stem and stem joints;  beginning to appear when the leaves are partly grown in the early summer through late October; each flower about 0.3 cm long, with five pale pink rose-like petals, distinguishable only with magnification; generally only a few flowers being open at any time. 

Fruit:  Achene, round or nearly round, shiny and smooth; 2.2 to 3.5 mm in diameter; flat surface on 1 side and concave on the other; black to dark brown; with a single small seed. 

Stem:  Upright, branched, knotted stem; with papery sheath where leaves attach; swollen at the nodes; green or reddish-green; 0.3 to 1.2 m tall, sometimes sprawling as it gets bigger. 

Form:  Annual, loosely branched forb. 

Discussion

Polygonum means "many joints or knees", most likely referring to the knobby nature of the stem.  The species name persicaria means "from Persia", though Lady's Thumb gets the persicaria because its leaves look like the leaves of a peach tree.  The common names "pepperweed, smartweed, and bity-tongue" are sometimes applied to Lady's Thumb because it looks like another plant with an acrid, spicy taste, though Lady's Thumb itself lacks that characteristic.  The purple spot on the leaves was said to be caused when the Virgin Mary pinched the leaves and left a heart-shaped mark, thus the name "Virgin's Thumb".  The name "Heart's Ease" came from the idea that the heart-shaped mark was a sign that the plant held a remedy for heart problems.

Polygonum persicaria is thought to be an introduced species in North America, possibly transferred to the United States from Scotland.

The seed of the Lady's Thumb is eaten as food by various animals, such as waterfowl, shorebirds, quail, song birds, and even chipmunks.  It also provides cover and bedding for pheasants. 

In the present time some people use Lady's Thumb as duck and animal feed.

Europeans used Lady's Thumb as a medicine for heart problems. 

Distinguishing Characteristics

Lady's Thumb has a purple V-shaped or heart-shaped spot on its lower leaves and pink cone-shaped flower spikes.  The stipules are edged with short bristles instead of being smooth or having fuzz.

Distribution

Throughout the United States; in flooded or wet soil, roadsides, ditches, cultivated ground, waste places, and pond banks.

Images

Click each small picture to see a larger image. 

October, 2003 EW	October, 2003 TN	October, 2003 EW
October, 2003 TN	October, 2003 EW

Location

N 39.27932°     W -89.89064°
Southwest corner of vacant lot by McDonald's, 700 block West Main, Carlinville, Macoupin County, IL.     

Copyright

Photos © 2003 Tyler Newingham and Eric Wills, Carlinville High School, linke@carlinvilleschools.net       

References

Peterson, Roger Tory and Margaret McKenny. 1968. Wildflowers.   Houghton Mifflin Company, Boston. 420 pp. 

Stubbendieck, James, Geir Y. Friisoe, and Margaret R. Bolick. 1994.  Weeds of Nebraska and the Great Plains. Nebraska Dept. of Agriculture, Bureau of Plant Industry, Lincoln. 589 pp.

Werner, Jr., William E. 1988. Life and lore of Illinois wildflowers.  Illinois State Museum, Springfield. 238 pp.

University of Kentucky, College of Agriculture
http://www.uky.edu/Ag/Agronomy/Weeds/ladysthumb.htm 

 Click here to return to the plant list for Carlinville High School's South-Central Illinois flora studies.