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Polygonum sagittatum L.

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.

Plants: 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.

Leaves: Shaped like arrowheads, attached via short ⅜" (1 cm) stems. The base of each leaf is clasping—it tends to wrap around the stem. Leaf edges also have tiny prickles.

Flowers: 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: Small nutlets, brown to black.

 

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

8/17/2020 · Otter Brook Preserve, Harpswell, Maine
≈ 7 × 4½" (18 × 12 cm)

These similar species are most easily distinguished by leaf shape:

 
Polygonum arifolium
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Polygonum sagittatum

Polygonum perfoliatum
Common Name

halberd-leaved tearthumb

arrow tearthumb

Asiatic tearthumb
Plant 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. Vines have reddish stems with backward-pointing hooks that allow it to clamber over other plants.
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. Flowers and fruits emerge from the ocreas. Flowers are white, but inconspicuous.
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. Mile-a-minute vine has leaves that are almost perfect triangles, small curved barbs along its stems, and saucer-shaped leaves (ocreas) at its stem nodes. Although ocreas are present in all Polygonums, they usually take the form of a fibrous sheath wrapped tightly around the plant stem.
Fruit Seeds are rounded reddish-brown nutlets about ⅛" (3.2 mm) around Small nutlets, brown to black. Tightly packed clusters of 10-30 lobed metallic blue fruits, each about ⅛-¼" (3.2-6.3 mm) around. Each lobe or segment contains a single glossy, black or reddish black seed.
Range/ Zones

Habitats Marshes, swamps, wet meadows Wet, marshy ground Almost anywhere there are warm moist or wet open areas: woods, wetlands, roadsides, fields, stream banks, forest edges.
Type Wild Wild Wild
Occurrence Common Common Invasive

 

Online References:

Polygonum sagittatum on

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

Polygonum sagittatum on

Polygonum sagittatum on spes.vt.edu

Polygonum sagittatum at the Lady Bird Johnson Wildflower Center

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

8/17/2020 · Otter Brook Preserve, Harpswell, Maine
≈ 10 × 6" (24 × 16 cm)

Polygonum sagittatum (arrow tearthumb)

7/20/2021 · Otter Brook, Harpswell, Maine
≈ 6 × 4" (16 × 10 cm)

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

8/18/2010 · J. Harry Rich Woods, off Nod Rd., Groton, Mass­a­chu­setts
≈ 3 × 3" (7.6 × 7.4 cm)

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

8/15/2021 · Bass Falls Preserve, Alna, Maine
≈ 2½ × 2½" (6.6 × 6.7 cm)

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

8/15/2021 · Bass Falls Preserve, Alna, Maine
≈ 3½ × 6" (9.4 × 14 cm)

Persicaria sagittata (L.) Gross.

Polygonum sagittatum L. var. gracilentum Fernald

Tracaulon sagittatum (L.) Small

Truellum sagittatum (L.) Soják

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

 

Polygonum sagittatum description by Thomas H. Kent, last updated 8 Sep 2021.

© FloraFinder.org. All rights reserved.


 

Polygonum sagittatum (arrow tearthumb)

8/15/2021 · Bass Falls Preserve, Alna, Maine
≈ 4 × 4" (11 × 10 cm)

Polygonum sagittatum (arrow tearthumb)

7/20/2021 · Otter Brook, Harpswell, Maine
≈ 2 × 3" (5.7 × 8 cm)

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

8/15/2021 · Bass Falls Preserve, Alna, Maine
≈ 4½ × 2½" (11 × 7.2 cm)

Polygonum sagittatum (arrow tearthumb)

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

Polygonum sagittatum (arrow tearthumb)

8/15/2021 · Bass Falls Preserve, Alna, Maine
≈ 4½ × 3½" (11 × 9.4 cm)

Polygonum sagittatum (arrow tearthumb)

9/11/2010 · Nashua River Rail Trail, Groton Center, Groton, Mass­a­chu­setts
≈ 5 × 4" (13 × 10 cm)

Polygonum sagittatum (arrow tearthumb)

8/28/2021 · Otter Brook Preserve, Harpswell, Maine
≈ 2 × 2" (5.7 × 5.3 cm)

Range:

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