The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

false water pepper, false water-pepper smartweed, mild waterpepper, renouée faux-poivre-d'eau, swamp smartweed, water-pepper

r enouée robuste, stout dotted smartweed, stout smartweed

Habit Plants perennial, 1.5–10 dm; roots also often arising from proximal nodes; rhizomes often present. Plants perennial, 3–20 dm; roots also sometimes arising from proximal nodes; rhizomes present, stolons sometimes present.
Stems

decumbent to ascending, usually branched, without noticeable ribs, glabrous or obscurely strigose distally.

ascending, usually branched proximally, scarcely ribbed, glabrous, glandular-punctate;

branches sometimes creeping and rooting at nodes.

Leaves

ocrea brown, cylindric, 5–23 mm, chartaceous, base inflated, margins truncate, ciliate with bristles (2–)4–10 mm, surface glabrous or strigose, not glandular-punctate;

petiole 0.2–2 cm, glabrous or strigose;

blade without dark triangular or lunate blotch adaxially, broadly lanceolate to linear-lanceolate, 5–25 × 0.4–3.7 cm, base tapered or acute, margins antrorsely appressed-pubescent, apex acuminate, faces glabrous or appressed-pubescent along midveins and sometimes on faces, usually punctate abaxially.

ocrea light brown, cylindric, 10–15 mm, chartaceous, base inflated, margins truncate, ciliate with bristles 3–12 mm, surface strigose, glandular-punctate;

petiole 0.2–2 cm, glandular-punctate;

blade without dark triangular or lunate blotch adaxially, lanceolate to elliptic-lanceolate, 4–20 × 2–4.5 cm, base tapered, margins antrorsely strigose, apex acute to acuminate, faces glabrous or main veins scabrous, glandular-punctate.

Inflorescences

terminal, sometimes also axillary, erect, uninterrupted or interrupted proximally, 30–80 × 2–5 mm;

peduncle 10–30 mm, glabrous or strigose;

ocreolae overlapping distally, often not overlapping proximally, margins ciliate with bristles to 2(–3) mm.

terminal and axillary, erect, uninterrupted, 20–80 × 5–10 mm;

peduncle 5–40 mm, glandular-punctate;

ocreolae usually overlapping, margins eciliate or proximal ones sometimes ciliate with bristles to 1 mm.

Pedicels

ascending, 1–1.5 mm.

ascending to spreading, 2–5 mm.

Flowers

bisexual or unisexual and staminate, 2–6 per ocreate fascicle, homostylous;

perianth roseate proximally, roseate, white, or greenish white distally, not glandular-punctate or sometimes glandular-punctate with punctae on tubes and inner tepals, scarcely accrescent;

tepals 5, connate ca. 1/3–1/2 their length, obovate, 2.5–4 mm in bisexual flowers, 1.5–2.5 mm in staminate flowers, veins prominent or not, not anchor-shaped, margins entire, apex obtuse to rounded;

stamens 8, included or exserted in staminate flowers;

anthers pink or red, elliptic to ovate;

styles 3, connate near middle.

2–4 per ocreate fascicle, homostylous;

perianth greenish proximally, white distally, glandular-punctate with punctae ± uniformly distributed, slightly accrescent;

tepals 5, connate ca.1/3 their length, obovate, 3.2–4.2 mm, veins prominent or not, not anchor-shaped, margins entire, apex obtuse to rounded;

stamens 6–8, included;

anthers pink or red, elliptic;

styles 3, connate proximally.

Achenes

included or apex exserted, brown to brownish black or black, 3-gonous, 1.5–3 × 1–2.3 mm, shiny, smooth.

included or apex exserted, dark brown to brownish black, 3-gonous, 2.7–3.6 × 2–2.5 mm, shiny, smooth.

Persicaria hydropiperoides

Persicaria robustior

Phenology Flowering Jun–Nov. Flowering Jul–Oct.
Habitat Wet banks and clearings, shallow water, marshes, moist prairies, ditches Peaty shores, often in water on coastal plain or near coast
Elevation 0-1500 m (0-4900 ft) 0-1500 m (0-4900 ft)
Distribution
from FNA
AK; AL; AR; AZ; CA; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; ND; NE; NH; NJ; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; VA; VT; WA; WI; WV; BC; NB; NS; ON; QC; Mexico; Central America; South America
[WildflowerSearch map]
[BONAP county map]
from FNA
CT; DE; FL; IN; KY; MA; MD; ME; MI; MO; NH; NJ; NY; OH; PA; RI; TX; VA; NS; ON; QC; Central America; South America; West Indies
[WildflowerSearch map]
[BONAP county map]
Discussion

The extreme variability in Persicaria hydropiperoides is reflected in its extensive synonymy. Among the segregates most often recognized in floras and checklists is P. opelousana, which C. B. McDonald (1980) showed to be broadly sympatric and highly interfertile with P. hydropiperoides. Consistent with this conclusion, R. S. Mitchell (1971) found that P. hydropiperoides and P. opelousana are unique among native North American smartweeds in consistently possessing multicellular plate-glands on the abaxial surface of their leaves. Such glands also are found on P. maculosa, an introduced European species.

Herbarium specimens of Persicaria hydropiperoides sometimes are misidentified as P. maculosa, especially when the roots are missing. The former species may be distinguished reliably by its achenes all trigonous (trigonous and biconvex achenes are mixed in the inflorescences of P. maculosa) and bristles on the margins of the ocreae that average longer. M. L. Fernald (1922c) reported hybrids with P. robustior from Nova Scotia.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Persicaria robustior often is synonymized with P. punctata.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 5, p. 585. FNA vol. 5, p. 584.
Parent taxa Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria
Sibling taxa
P. amphibia, P. arifolia, P. bicornis, P. bungeana, P. capitata, P. careyi, P. chinensis, P. glabra, P. hirsuta, P. hydropiper, P. lapathifolia, P. longiseta, P. maculosa, P. meisneriana, P. minor, P. nepalensis, P. orientalis, P. pensylvanica, P. perfoliata, P. punctata, P. robustior, P. sagittata, P. setacea, P. virginiana, P. wallichii
P. amphibia, P. arifolia, P. bicornis, P. bungeana, P. capitata, P. careyi, P. chinensis, P. glabra, P. hirsuta, P. hydropiper, P. hydropiperoides, P. lapathifolia, P. longiseta, P. maculosa, P. meisneriana, P. minor, P. nepalensis, P. orientalis, P. pensylvanica, P. perfoliata, P. punctata, P. sagittata, P. setacea, P. virginiana, P. wallichii
Synonyms Polygonum hydropiperoides, P. opelousana, P. paludicola, Polygonum hydropiperoides var. adenocalyx, Polygonum hydropiperoides var. asperifolium, Polygonum hydropiperoides var. breviciliatum, Polygonum hydropiperoides var. bushianum, Polygonum hydropiperoides var. digitatum, Polygonum hydropiperoides var. opelousanum, Polygonum hydropiperoides var. psilostachyum, Polygonum opelousanum, Polygonum opelousanum var. adenocalyx Polygonum punctatum var. robustius, P. punctata var. robustior, Polygonum punctatum var. majus, Polygonum robustius
Name authority (Michaux) Small: Fl. S.E. U.S., 378. (1903) (Small) E. P. Bicknell: Bull. Torrey Bot. Club 36: 455. (1909)
Web links