Foothills, montane. Moist areas, pond edges, irrigation ditches. Summer.
Near Canyons of the Ancients National Monument, August 22, 2014.

Persicaria lapathifolia is a highly variable species, so much so that a partial synonymy in Intermountain Flora takes a full page. The plant ranges, according to IMF "from tiny, erect herbs barely 5 cm tall with linear, lanate leaves and small, erect inflorescences to robust herbs [as shown here] nearly 2 m tall with large, lanceolate leaves and elongate, drooping racemes".

Almost all floras agree that an arching inflorescence, a peduncle with yellow glands, and an anchor-shaped venation on the tepals are diagnostic characteristics for this species. The plants shown on this page certainly have the first and second characteristics, but most of the tepals have no veins, some have several faint veins, and a very few have anchor-shaped veins -- but the veins are only visible with a microscope. One flora does indicate, however, that the venation sometimes comes only with age.

Persicaria lapathifolia and P. pensylvanica are very similar, separated by upright vs. arching inflorescences, yellow vs. purple glands on the peduncle, and the venation on the tepals.

Stanley Welsh often has the most enlightening views on matters botanical and I like his comment on these two supposedly distinct species. Welsh tells us, as other botanists do, that the two species are separated from each other on the basis of the tepal venation, "but these [veins] are not always readily apparent and in some specimens must be sought with great care. Whether [P. pensylvanica] should be recognized as a taxon distinct from P. lapathifolia in any sense is questionable"

I should also add, regarding the supposed diagnostic value of the color of the peduncle glands, that James Reveal, Polygonaceae expert, indicates in his Intermountain Flora description of the two species: P. lapathifolia peduncles are "usually stipitate-glandular" and P. pensylvanica peduncles are "glabrous or stipitate glandular". Reveal does not indicate that the color of the glands is diagnostic; he does not even mention the color.

Persicaria lapathifolia was named and described by Linnaeus in 1753 and is native through Europe and western Asia and many parts of the northern hemisphere, including the United States. "Persica" is Latin for "peach" and "aria" means "pertaining to". The name refers to the similarity of the leaves of the two plants. "Lapathifolia" is Latin for "with Dock-like leaves".

Foothills, montane. Moist areas, pond edges, irrigation ditches. Summer.
Near Canyons of the Ancients National Monument, August 22, 2014.

The photograph focuses on the united stipules, the sheath over the stem joint, which in the Persicaria is called the "ocreae". The ocreae will split and peel as the joint swells from the young joint shown at left.

Foothills, montane. Moist areas, pond edges, irrigation ditches. Summer.
Near Canyons of the Ancients National Monument, August 22, 2014.

Numerous flowers are tightly clustered on 1-3" stems. Flowers typically have 4 tepals. The tepals of the plants shown on this page glisten because of innumerable glandular dots  --  especially noticeable at the bottom of the photograph.

Seeds develop quickly and by the time the top flowers open, the bottom are often swelling with seeds.

Foothills, montane. Moist areas, pond edges, irrigation ditches. Summer.
Near Canyons of the Ancients National Monument, August 22, 2014.

The peduncles at left have few glands, but some peduncles have far more.

Foothills, montane. Moist areas, pond edges, irrigation ditches. Summer.
Near Canyons of the Ancients National Monument, August 22, 2014.

Top and bottom of the leaves vary in pubescence and glandular pits. I enhanced the glossiness of the underside of the leaf so you could see the pits. In the top photograph notice the forward pointing stiff hairs at the edge of the leaf.

Foothills, montane. Moist areas, pond edges, irrigation ditches. Summer.
Near Canyons of the Ancients National Monument, August 22, 2014.

Seeds are about 2 mm x 2 mm.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Persicaria lapathifolia