- You are here:
- Simple Key
- All other flowering non-woody plants
- All other herbaceous, flowering dicots
- Persicaria amphibia
Persicaria amphibia — water smartweed
Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.
Facts
water smartweed is a native perennial that inhabits still or slow moving water of lakes, rivers, marshes and swamps, and is variable in habit, growing underwater, floating or emergent. The inflorescence is a dense cluster of many five-lobed pink flowers.
Habitat
Anthropogenic (man-made or disturbed habitats), lacustrine (in lakes or ponds), marshes, riverine (in rivers or streams), shores of rivers or lakes, swamps, wetland margins (edges of wetlands)
New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
Found this plant? Take a photo and post a sighting.
Characteristics
- Habitat
-
- aquatic
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Flower petal color
- pink to red
- Leaf type
- the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
- Leaf arrangement
- alternate: there is one leaf per node along the stem
- Leaf blade edges
- the edge of the leaf blade is entire (has no teeth or lobes)
- Flower symmetry
- there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
- Number of sepals, petals or tepals
- there are five petals, sepals, or tepals in the flower
- Fusion of sepals and petals
- the petals or the sepals are fused into a cup or tube
- Stamen number
- 5
- Fruit type (general)
- the fruit is dry but does not split open when ripe
- Fruit length
- 2–3 mm
-
Clonal plantlets
- Bulbils
- the plant does not appear to have bulbils
- Bulblets replace flowers
- there are no bulblets where the flowers are located
-
Flowers
- Anther color
- there is a noticeable pink, reddish or purplish tint to the anthers
- Anther opening
- the anthers have narrow slits or furrows that run lengthwise along the anthers
- Anther spurs
- the anthers do not have spurs on them
- Calyx growth after flowering
- the calyx does not grow to cover or partially cover the fruit
- Calyx symmetry
- there are two or more ways to evenly divide the calyx (the calyx is radially symmetrical)
- Carpels fused
- the carpels are fused to one another
- Cilia on petals
- the petal margins do not have cilia
- Corolla palate
- no
- Corona lobe length
- 0 mm
- Epicalyx
- the flower does not have an epicalyx
- Epicalyx number of parts
- 0
- Filament surface
- the filament is smooth, with no hairs or scales
- Flower description
- the flower has a superior ovary, and lacks a hypanthium
- Flower orientation
- the flower points upwards or is angled outwards
- Flower petal color
- pink to red
- Flower reproductive parts
-
- the flower has both pollen- and seed-producing parts
- the flower has either only pollen- or only seed-producing parts
- Flower symmetry
- there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
- Flowers sunken into stem
- no
- Form of style
- the style is branched above the base
- Fringed petal edges
- the petals are not fringed
- Fusion of sepals and petals
- the petals or the sepals are fused into a cup or tube
- Hairs on inflorescence
-
- at least some of the hairs on the axis of the inflorescence have glands
- the axis of the inflorescence has no hairs on it
- Horns in hoods (Asclepias)
- NA
- Hypanthium
-
- the flower does not have a hypanthium
- the flower has a hypanthium
- Inflorescence length
- 10–150 mm
- Inflorescence one-sided
- the flowers are arrayed in a spiral around the inflorescence axis or branches, or occur singly, or in several ranks
- Inflorescence width
- 8–20 mm
- Inner tepals (Rumex)
- NA
- Length of flower stalk
- 0.5–1.5 mm
- Length of peduncle
- 10–50 mm
- Marks on petals
- there are no noticeable marks on the petals
- Nectar spur
- the flower has no nectar spurs
- Number of branches in umbel
- 0
- Number of carpels
- 2
- Number of pistils
- 1
- Number of sepals, petals or tepals
- there are five petals, sepals, or tepals in the flower
- Number of styles
- 2
- Ovary position
- the ovary is above the point of petal and/or sepal attachment
- Perianth shape
- the perianth is campanulate (bell-shaped, with a tube about as long as wide, flaring at the mouth)
- Petal and sepal arrangement
- the flower includes two cycles of petal- or sepal-like structures
- Petal and sepal colors
- pink to red
- Petal appearance
- the petals are thin and delicate, and pigmented (colored other than green or brown)
- Petal folds or pleats
- the petals of the flower do not have folds or plaits
- Petal glandular dots or scales
- no
- Petal hairs (Viola)
- NA
- Petal hairs on inner/upper surface
- there are no hairs on the inner/upper petal surface
- Petal length
- 4–6 mm
- Petal number
- 2
- Petal shape
-
- the petal outline is elliptic (shaped like an ellipse; widest near the middle and tapering at both ends)
- the petal outline is obovate (roughly egg-shaped, but with the widest point above the middle of the leaf blade)
- Petal tip shape
-
- the petal tip is acute (sharply pointed)
- the petal tip is rounded
- Petal tips (Cuscuta)
- NA
- Raceme attachment (Veronica)
- NA
- Reproductive system
-
- all the flowers have both carpels and stamens (synoecious)
- all the flowers on each plant have only carpels or only stamens, with only one type being present on each plant (dioecious)
- Scales inside corolla
- no
- Sepal and petal color
- the petals and sepals are similar
- Sepal appearance
- the sepals resemble petals in color and texture
- Sepal appendages
- the sepals do not have appendages on them
- Sepal appendages (Oenothera)
- NA
- Sepal cilia
- the sepals do not have cilia
- Sepal color
- pink to red
- Sepal features
- NA
- Sepal length
- 4–6 mm
- Sepal number
- 3
- Sepal shape
-
- the sepal outline is eliiptic (widest near the middle and tapering at both ends)
- the sepal outline is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
- Sepal texture
- the sepals are either very thin but flexible, like a membrane, or they are leaf-like in texture
- Sepal tip shape
-
- the sepal tip is acute (is sharply pointed)
- the sepal tip is rounded
- Sepal uniformity
- all the sepals are about the same size
- Sepals fused only to sepals
- the sepals are fused to each other (not other flower parts), at least near their bases
- Stamen morphology
- the stamens within each cycle are the same
- Stamen number
- 5
- Stamen relative length
-
- anything
- anything
- Staminodes
- there are no staminodes on the flower
- Style length
- Up to 4 mm
- Style petal-like
- the styles are not petal-like
- Style relative length
-
- the stigma does not protrude beyond the mouth of the corolla
- the stigma protrudes beyond the mouth of the corolla
- Umbel flower reproductive parts
- NA
- Upper lip of bilabiate corolla
- NA
-
Fruits or seeds
- Achene relative orientation
- the achenes are perpendicular to the plane of the perianth (vertical)
- Achene shape
-
- the achenes are circular in outline
- the achenes are oval in outline
- Achene surface (Polygonum)
- NA
- Achene type
- the fruit is an achene (dry, indehiscent, and usually one-seeded)
- Berry color
- NA
- Capsule color (Viola)
- NA
- Capsule ribs
- NA
- Capsule splitting
- NA
- Carpel beak length
- 0 mm
- Fruit (pyxis) dehiscence
- NA
- Fruit cross-section
- the fruit is at least somewhat flattened
- Fruit features (Brassicaceae)
- NA
- Fruit length
- 2–3 mm
- Fruit length relative to sepals
- the fruit is shorter than its associated sepals
- Fruit locules
- one
- Fruit shape
- the fruit is flat or strongly compressed
- Fruit stalk orientation
- the fruits point upward or spread or curve outward
- Fruit type (general)
- the fruit is dry but does not split open when ripe
- Fruit type (specific)
- the fruit is an achene (dry, usually one-seeded, does not separate or split open at maturity)
- Fruit width
- 1.5–2.6 mm
- Hair type on fruit
- NA
- Hairs on fruit
- the fruits are not hairy
- Legumes (Fabaceae)
- NA
- Mericarp length
- 0 mm
- Mericarp segment shape (Desmodium)
- NA
- Other markings on berry
- NA
- Ovary stipe
- the ovary or fruit does not have a stipe
- Ovary stipe length
- 0 mm
- Placenta arrangement
- the plant has basal placentation, where one or a few ovules develop at the base of a simple or compound ovary
- Rows of seeds in fruit (Brassicaceae)
- NA
- Schizocarpic fruit compression
- NA
- Schizocarpic fruit segments
- 0
- Seed number
- 1
- Septum in fruit (Brassicaceae)
- NA
- Wings on fruit
- the fruit does not have wings on it
- prickles on fruits
- the fruits do not have thorn-like defensive structures
-
Glands or sap
- Glands on leaf blade
- the leaf blades do not have glandular dots or scales
- Sap
- the sap is clear and watery
- Sap color
- the sap is clear
-
Growth form
- Growth form
- the plant is an herb (it has self-supporting stems)
- Horizontal rooting stem
-
- the plant does not have stolons
- the plant has stolons
- Lifespan
- the plant lives more than two years
- Parasitism
- the plant is not parasitic
- Plant color
- the leaves or young stems of the plant are green
- Plants darken when dry
- no
- Spines on plant
- the plant has no spines
- Underground organs
- the plant has a rhizome (a horizontal underground stem with roots growing from it)
-
Leaves
- Bracteole number (Apiaceae)
- 0
- Bracteoles
- the plant has bracteoles between the primary bracts and the flowers
- Bracts in plantain (Plantago)
- NA
- Final leaf segment length (compound lvs only)
- 0 mm
- Final leaf segment length to width ratio (compound lvs only)
- 0
- Final leaf segment width (compound lvs only)
- 0 mm
- Floral bract texture
- NA
- Floral bracts
- the flower does not have bracts
- Flower bract length
- 0 mm
- Hairs on leaf stalk
-
- the petiole has hairs on it
- the petiole has no hairs on it
- Hairs on underside of leaf
-
- the underside of the leaf is fuzzy or hairy
- the underside of the leaf is not hairy, or it has very few hairs
- Hairs on upper side of leaf
-
- the upper side of the leaf is fuzzy or hairy
- the upper side of the leaf is not hairy, or it has very few hairs
- Hooked hairs on underside of leaf
- no
- Inflated hairs on leaf
- the leaf blade does not have inflated hairs on it
- Leaf arrangement
- alternate: there is one leaf per node along the stem
- Leaf blade base
-
- the leaf has a distinct leaf stalk (petiole)
- the leaf has no stalk
- Leaf blade base shape
-
- the base of the leaf blade is cuneate (wedge-shaped, tapers to the base with relatively straight, converging edges), or narrow
- the base of the leaf blade is rounded
- Leaf blade base symmetry
- the leaf blade base is symmetrical
- Leaf blade bloom
- the underside of the leaf has no noticeable bloom
- Leaf blade edges
- the edge of the leaf blade is entire (has no teeth or lobes)
- Leaf blade flatness
- the leaf is flat (planar) at the edges
- Leaf blade hairs
- the leaf blade has simple hairs with no glands, and not tangled or wooly
- Leaf blade length
- 20–230 mm
- Leaf blade primary vein pattern
- the secondary veins branch off at intervals from the primary vein
- Leaf blade shape
-
- the leaf blade is elliptic (widest near the middle and tapering at both ends)
- the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
- the leaf blade is oblong (rectangular but with rounded ends)
- the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
- Leaf blade surface colors
- the upper side of the leaf blade is relatively uniform in color
- Leaf blade texture
- the leaf blade has a fleshy or spongy texture
- Leaf blade vein pattern
- the major veins of the leaf blade branch, but do not rejoin
- Leaf blade veins
- the leaf blade has one main vein running from the base towards the tip (it may or may not have secondary veins)
- Leaf blade width
- 10–80 mm
- Leaf duration
- the leaves drop off in winter (or they whither but persist on the plant)
- Leaf form
- the leaves are green, with an expanded blade and a leaf-like texture
- Leaf hair orientation
- the hairs are flat against the leaf surface, mostly pointing towards the leaf tip
- Leaf shiny
- the upper side of the leaf is dull or slightly shiny
- Leaf spines
- there are no spines on the leaf edges
- Leaf stalk
-
- the leaves have leaf stalks
- the leaves have no leaf stalks, but attach directly to the stem
- Leaf stalk attachment to leaf
-
- NA
- the petiole attaches at the basal margin of the leaf blade
- Leaf stalk base
- the petiole base is narrow where it attaches to the stem
- Leaf stalk length
- 1–70 mm
- Leaf teeth and lobes
- the edge of the leaf blade is entire (has no teeth or lobes)
- Leaf tip
-
- the tip of the leaf blade is acuminate (tapers to a long, thin point)
- the tip of the leaf blade is acute (sharply pointed)
- Leaf type
- the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
- Leaf types
- NA
- Leaf variation
- the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
- Leaflet number
- 0
- Leaflet petiolules
- NA
- Leaves per node
- there is one leaf per node along the stem
- Pinnately compound leaf type
- NA
- Specific leaf type
- the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
- Stipels
- NA
- Stipule features
-
- at least some of the stipules on a plant are expanded and with leaf-like color and/or texture at their tips
- glabrous on the surface
- the stipules are hairy with hairs standing out at a 45 to 90 degree angle, or pressed to the stipule surface
- the stipules are straight (or somewhat slanted) across the top
- the stipules do not have tiny hairs (cilia) at their tips
- the stipules have a fringe of cilia along the top edge
- Stipule length
- 5–50 mm
- Stipule shape
- the stipules are tubular (cylindrical and hollow)
- Stipules
- the plant has stipules
- Teeth per side of leaf blade
- 0
-
Place
- Habitat
-
- aquatic
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- edges of wetlands
- in lakes or ponds
- in rivers or streams
- man-made or disturbed habitats
- marshes
- shores of rivers or lakes
- swamps
-
Scent
- Plant odor
- the plant does not have much of a smell
-
Stem, shoot, branch
- Branched tendrils
- NA
- Direction of stem hairs
-
- the hairs are pressed flat against the plant, pointing towards the plant's tip
- the hairs point mostly upwards to outwards
- Flowering stem cross-section
- the flowering stem is circular, or with lots of small angles so that it is roughly circular
- Hair between stem nodes
-
- the stem has hairs between the nodes
- the stem has no hairs between the nodes
- Hairs between stem nodes
-
- the hairs on the stem are plain, without glands or branches, and not tangled
- the stem has no hairs between the nodes
- Hooked hairs on stem between nodes
- no
- Leaves on stem
- there is at least one full leaf above the base of the flowering stem
- Plant height
- 20–300 cm
- Stem bloom
- there is no powdery or waxy film on the stem
- Stem nodes swollen
- the stem is swollen at the nodes
- Stem orientation
-
- the stems are upright or angled outwards
- the stems trail at the base, but may turn upwards at the tips
- Tendril origin
- NA
- Tendrils
- the plant does not have tendrils
- Wings on stem
- the stem does not have wings on it
Wetland status
Occurs only in wetlands. (Wetland indicator code: OBL)
In New England
Distribution
- Connecticut
- present
- Maine
- present
- Massachusetts
- present
- New Hampshire
- present
- Rhode Island
- present
- Vermont
- present
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Maine
- unranked (S-rank: SNR)
- Massachusetts
- widespread (S-rank: S5)
Subspecies and varieties
Our subspecies is Persicaria amphibia (L.) S.F. Gray ssp. laevimarginata (Hultén) Soják.
From Flora Novae Angliae dichotomous key
1. Persicaria amphibia (L.) S.F. Gray ssp. laevimarginata (Hultén) Soják N
water smartweed. Persicaria amphibia (L.) S.F. Gray var. stipulacea (Coleman) Hara; Polygonum amphibium L. ssp. laevimarginatum Hultén; P. amphibium L. var. natans Michx.; P. amphibium L. var. stipulaceum Coleman; P. coccineum Muhl. ex Willd. var. rigidulum (Sheldon) Stanford; P. natans (Michx.) Eat. • CT, MA, ME, NH, RI, VT. Shallow, still or slow-moving water of lakes and rivers, marshes, shorelines, swamps, ditches. Numerous attempts have been made to subdivide the Persicaria amphibia complex, some with a priori assumptions of the morphological variation. Though some intermediate material does exist, two taxa can be recognized in North America—an aquatic species with an amphibious form when water levels decline ( P. amphibia) and a wetland species that can form floating leaves when submerged ( P. coccinea). It is known that these taxa have a genetic basis; however, several characters that have been deemed critically important are known to be almost completely controlled by environment (specifically, depth of inundation). These include pubescence of the leaf blades, presence/absence of stipitate-glands on the peduncle, and apex shape of leaf blades. Preliminary surveys suggest about 10% of our material shows substantial intermediacy. These plants are probably best interpreted as F₁ hybrids. European P. amphibia (ssp. amphibia) is very similar to North American P. amphibia (ssp. laevimarginata), except that it usually has truncate- to cordate-based floating leaf blades that frequently show stout, forward-pointing cilia along the margin and never produces foliaceous, outward-flanged stipules on emersed forms.
Native to North America?
Yes and no (some introduced)
Sometimes confused with
- Persicaria coccinea:
- widest leaf blades mostly 32-63 mm wide, primary inflorescece mostly 29-90 mm long, and stipules on plants that stand up out of the water lacking a green, out-flaring flange (vs. P. amphibia, with the widest leaf blades mostly 17-29 mm wide, primary inflorescence mostly 13-28 mm long, and stipules on plants that stand up out of the water with a green, out-flaring flange).
Synonyms
- Persicaria amphibia var. stipulacea (Coleman) Hara
- Polygonum amphibium L. ssp. laevimarginatum Hultén
- Polygonum amphibium L. var. natans Michx.
- Polygonum amphibium L. var. stipulaceum Coleman
- Polygonum coccineum Muhl. ex Willd. var. rigidulum (Sheldon) Stanford
- Polygonum natans (Michx.) Eat.