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Polygonum sagittatum

Polygonum sagittatum L.

Persicaria sagittata (L.) Gross.

Polygonum sagittatum L. var. gracilentum Fernald

Tracaulon sagittatum (L.) Small

Tracaulon sagittatum (L.) Small var. gracilentum (Fernald) C.F. Reed

Truellum sagittatum (L.) Soják

Arrow Tearthumb

KingdomPlantaePlants, but not fungi, lichens, or algae
SubkingdomTracheobiontaVascular plants—plants with a “circulatory system” for delivering water and nutrients
DivisionMagnoliophytaFlowering plants, also known as angiosperms
ClassMagnoliopsidaDicotyledons—plants with two initial seed leaves
SubclassCaryophyllidaeCacti, many other succulents, carnivorous plants, and leadworts
OrderCaryophyllalesIncludes cacti, carnations, amaranths, ice plants, and many carnivorous plants
FamilyPolygonaceaeKnotweed or smartweed family
GenusPolygonumGreek poly, “many,” and gonu, “knee,” for the swollen jointed stems
SpeciessagittatumLatin for “Arrow-shaped”

About plant names...

These North American natives favor wet, marshy ground.

Identification: These plants have hollow vinelike stems up to 3-6' (91-182 cm) long, with squared edges and tiny, backward-pointing prickles. The prickles help the plant attach to surrounding plants as it meanders over them. Stems may be green, pink, or red. The leaves are shaped like arrowheads, attached via short ⅜" (1 cm) stems. The base of each leaf tends to wrap around the stem. Leaf edges also have tiny prickles. Flowerheads are less than ⅜" (1 cm) in diameter, white to pink in color. Each rounded flowerhead consists of 5-20 individual flowers at the end of a long stem, which emerges from a leaf node. Fruits are small nutlets, brown to black.

 

Polygonum sagittatum (Arrow Tearthumb)

8/18/2010 · J. Harry Rich Woods, off Nod Rd., Groton, MA
≈ 6 × 4" (15 × 10 cm)

Polygonum sagittatum (Arrow Tearthumb)

9/11/2013 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 5 × 4½" (13 × 12 cm)

Polygonum sagittatum (Arrow Tearthumb)

8/18/2010 · J. Harry Rich Woods, off Nod Rd., Groton, MA
≈ 5 × 3½" (13 × 9.2 cm)

These similar species are most easily distinguished by leaf shape:

 
Polygonum arifolium
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Polygonum sagittatum
Common Name

Halberd-leaved Tearthumb

Arrow Tearthumb
Flowers Flowerheads are less than ⅜" (1 cm) in diameter, white to light pink, with 5-20 individual flowers at the end of a long stem Flowerheads are less than ⅜" (1 cm) in diameter, white to pink in color. Each rounded flowerhead consists of 5-20 individual flowers at the end of a long stem.
Leaves Leaves are shaped like arrowheads, except that the backward-pointing barbs point outward (technically, “hastate”). Leaves are hairy, 4-4½" (10-11 cm) long Shaped like narrow arrowheads, attached via short ⅜" (1 cm) stems. The base of each leaf tends to wrap around the stem. Leaf edges also have tiny prickles.
Stem Vine has weak stems that are green, pink or red, with many tiny backward-pointing barbs, 24-48" (60-121 cm) long Stems 3-6' (91-182 cm) long, green, pink, or red, hollow, vinelike, with squared edges and tiny, backward-pointing prickles.
Fruit Seeds are rounded reddish-brown nutlets about ⅛" (3.2 mm) around Small nutlets, brown to black.
Range/ Zones

Habitats Marshes, swamps, wet meadows Wet, marshy ground
Type Wild Wild

 

Online References:

Polygonum sagittatum on Missouriplants.com

Polygonum sagittatum on the Connecticut Botanical Society's Connecticut wildflowers site

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

Polygonum sagittatum on the Virginia Tech Weed Identification Guide

Polygonum sagittatum at the Lady Bird Johnson Wildflower Center

Polygonum sagittatum (Arrow Tearthumb)

8/4/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 11 × 7" (27 × 18 cm)

Polygonum sagittatum (Arrow Tearthumb)

9/11/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 6 × 4" (15 × 10 cm)

Polygonum sagittatum (Arrow Tearthumb)

8/18/2010 · J. Harry Rich Woods, off Nod Rd., Groton, MA
≈ 4½ × 3" (11 × 7.9 cm)

Polygonum sagittatum (Arrow Tearthumb)

8/18/2010 · J. Harry Rich Woods, off Nod Rd., Groton, MA
≈ 4½ × 3" (11 × 7.9 cm)

Polygonum sagittatum (Arrow Tearthumb)

8/18/2010 · J. Harry Rich Woods, off Nod Rd., Groton, MA
≈ 5 × 3½" (13 × 9.2 cm)

Polygonum sagittatum description by Thomas H. Kent, last updated 17 Sep 2013.

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Polygonum sagittatum (Arrow Tearthumb)

9/14/2013 · Whitewater Rafting Trip, Barryville to Pond Eddy Leg, Delaware River, Barryville, PA
≈ 5 × 3½" (13 × 8.7 cm)

Polygonum sagittatum (Arrow Tearthumb)

9/11/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 7 × 4½" (17 × 11 cm)

Polygonum sagittatum (Arrow Tearthumb)

9/11/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 6 × 4" (15 × 10 cm)

Polygonum sagittatum (Arrow Tearthumb)

9/14/2013 · Whitewater Rafting Trip, Barryville to Pond Eddy Leg, Delaware River, Barryville, PA
≈ 5 × 3½" (13 × 8.7 cm)

Polygonum sagittatum (Arrow Tearthumb)

9/11/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 6 × 4" (15 × 10 cm)

Range:

About this map...