Polygonum persicaria (Lady’s thumb)

Polygonum persicaria L.

Persicaria persicaria (L.) Small nom. inval.

Persicaria puritanorum (Fernald) Soják

Persicaria maculata (Raf.) Gray

Persicaria maculosa Gray

Persicaria ruderalis (Salisb.) C.F. Reed

Persicaria ruderalis (Salisb.) C.F. Reed var. vulgaris (Webb & Moq.) C.F. Reed

Persicaria vulgaris Webb & Moq.

Polygonum dubium Stein

Polygonum fusiforme Greene

Polygonum minus auct. non Huds.

Polygonum minus Huds. var. subcontinuum (Meisn.) Fernald

Polygonum persicaria L. var. angustifolium Beckh.

Polygonum persicaria L. var. ruderale (Salisb.) Meisn.

Polygonum puritanorum Fernald

Persicaria persicaria (L.) Small

Lady’s thumb, persicaria, redleg, spotted ladysthumb, Adam’s plaster, lily of the valley

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Caryophyllidae	Cacti, many other succulents, carnivorous plants, and leadworts
Order	Caryophyllales	Includes cacti, carnations, amaranths, ice plants, and many carnivorous plants
Family	Polygonaceae	Knotweed or smartweed family
Genus	Polygonum	Greek poly, “many,” and gonu, “knee,” for the swollen jointed stems
Species	persicaria	“Peach-like,” the medieval name for knotweed

About plant names...

Lady’s thumb, a native of Europe and Asia, became naturalized throughout the entire United States after its introduction there.

Identification: The plants reach 3' (91 cm) in height, though smaller plants are common. Leaves are long and narrow, up to about 5" (12 cm) long and an inch wide. Tiny pink and white flowers form spikes up to 3" (7.6 cm) long—the most noticeable feature of these rather inconspicuous plants. Leaves sometimes have a dark triangular ”thumbprint” on them.

Edibility: The leaves and young shoots are “palatable and nutritious”^[1] leaf vegetables. Young leaves may be added to salads, or cooked and served with vinegar, tasting a bit like spinach.^[2]

Online References:

Polygonum persicaria on

Polygonum persicaria on CalPhotos

Polygonum persicaria at Alaskawildflowers.us

Polygonum persicaria on Turner Photographics' Wildflowers site

Polygonum persicaria on Plants for a Future, a resource and information centre for edible and otherwise useful plants

Polygonum persicaria on spes.vt.edu

Polygonum persicaria at the University of Wisconsin's Robert W. Freckmann Herbarium

Polygonum persicaria on eFloras

References:

Peterson, Lee Allen, Peterson Field Guides: Edible Wild Plants of Eastern/Central North America, Houghton Mifflin Company, 1977

9/3/2009 · Nashua River Rail Trail, Ayer, Massachusetts
≈ 4½ × 5" (11 × 13 cm)

9/9/2013 · J. Harry Rich Forest, Groton, Massachusetts
≈ 9 × 6" (23 × 16 cm)

9/9/2014 · Bemis Road, Pepperell, Massachusetts
≈ 6 × 9" (16 × 23 cm)

8/17/2013 · Hopkinton State Park, Hopkinton, Massachusetts
≈ 6 × 9" (16 × 23 cm) ID is uncertain

9/9/2014 · Bemis Road, Pepperell, Massachusetts
≈ 8 × 5" (19 × 13 cm)

7/17/2009 · Mt. Lebanon St, Trail, Pepperell, Massachusetts
≈ 10 × 7" (26 × 17 cm)

9/9/2013 · J. Harry Rich Forest, Groton, Massachusetts
≈ 6 × 6" (16 × 14 cm)

9/14/2009 · Near Nashoba Hospital, Ayer, Massachusetts
≈ 18 × 21" (45 × 53 cm)

8/18/2013 · Bemis Road, Townsend, Massachusetts
≈ 4½ × 4" (11 × 10 cm)

9/9/2014 · Bemis Road, Pepperell, Massachusetts
≈ 11 × 7" (28 × 18 cm)

8/7/2010 · Nashua River Rail Trail, near Nashoba Hospital, Ayer, Massachusetts
≈ 7 × 10" (16 × 25 cm)

Usually pink, but may be greenish white or purple. · 8/7/2010 · Nashua River Rail Trail, near Nashoba Hospital, Ayer, Massachusetts
≈ 4 × 4" (10 × 10 cm)

¹See the Wikipedia article

²See Peterson, Lee Allen, Peterson Field Guides Edible Wild Plants, Eastern/Central North America, Houghton Mifflin Company, 1977, p. 116.

Polygonum persicaria description by Thomas H. Kent, last updated 25 May 2020.

9/10/2016 · Arlington St., Groton, Massachusetts

8/18/2013 · Bemis Road, Townsend, Massachusetts
≈ 4½ × 7" (12 × 18 cm)

A bit pinker than usual. · 9/18/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 5 × 4½" (13 × 11 cm)

8/17/2013 · Hopkinton State Park, Hopkinton, Massachusetts
≈ 3½ × 5" (9.7 × 13 cm) ID is uncertain

9/10/2016 · Arlington St., Groton, Massachusetts

A bit pinker than usual. · 9/18/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 6 × 9" (15 × 23 cm)

9/9/2014 · Bemis Road, Pepperell, Massachusetts
≈ 6 × 8" (14 × 20 cm)

9/14/2009 · Near Nashoba Hospital, Ayer, Massachusetts
≈ 16 × 24" (41 × 62 cm)

8/3/2009 · 111 Near 119, Pepperell, Massachusetts
≈ 5 × 6" (13 × 15 cm)

9/9/2013 · J. Harry Rich Forest, Groton, Massachusetts
≈ 9 × 6" (23 × 16 cm)

9/9/2014 · Bemis Road, Pepperell, Massachusetts
≈ 6 × 8" (14 × 20 cm)

8/6/2009 · Nashua River Rail Trail, Groton, Massachusetts
≈ 4 × 3" (10 × 7.7 cm)

8/6/2009 · Nashua River Rail Trail, Groton, Massachusetts
≈ 5 × 3½" (12 × 9.2 cm)

8/7/2010 · Nashua River Rail Trail, near Nashoba Hospital, Ayer, Massachusetts
≈ 9 × 6" (22 × 15 cm)

9/9/2013 · J. Harry Rich Forest, Groton, Massachusetts
≈ 9 × 6" (23 × 16 cm)

Range:

About this map...