Persicaria maculosa Gray, Nat. Arr. Brit. Pl. 2: 269 1821. (syn: Persicaria fusiformis (Greene) Greene; Persicaria maculosa var. argentea Gray; Persicaria mitis Garsault [Invalid]; Persicaria mitis Delarbre; Persicaria persicaria (L.) Small; Persicaria salicifolia Gray; Polygonum biforme Wahlenb.; Polygonum fusiforme Greene; Polygonum persicaria L.; Polygonum persicaria var. ruderale (Salisb.) Meisn.; Polygonum puritanorum Fernald; Polygonum ruderale Salisb.);
Temp. Eurasia, N. Africa: Afghanistan, Albania, Algeria, Altay, Amur, Austria, Azores, Baleares, Baltic States, Belarus, Belgium, Bulgaria, Central European Rus, China North-Central, China South-Central, China Southeast, Corse, Czechoslovakia, Denmark, East European Russia, East Himalaya, Egypt, Finland, France, Germany, Great Britain, Greece, Hungary, Inner Mongolia, Iran, Iraq, Ireland, Irkutsk, Italy, Japan, Kazakhstan, Kirgizstan, Korea, Krasnoyarsk, Krym, Laos, Lebanon-Syria, Madeira, Manchuria, Morocco, Nepal, Netherlands, North Caucasus, North European Russi, Northwest European R, Norway, Pakistan, Poland, Portugal, Qinghai, Romania, Sardegna, Saudi Arabia, Sicilia, South European Russi, Spain, Sweden, Switzerland, Tadzhikistan, Transcaucasus, Tunisia, Turkey, Turkey-in-Europe, Turkmenistan, Ukraine, Uzbekistan, Vietnam, West Himalaya, West Siberia, Xinjiang, Yemen, Yugoslavia as per POWO;
Lady’s-thumb, Redshank, Spotted lady’s-thumb , Smart weed; 

Persicaria maculosa (syn. Polygonum persicaria) is an annual plant in the knotweed family, Polygonaceae. Common names include lady’s thumb,[1] spotted lady’s thumb, Jesusplant, and redshank.[2]
It is native to Eurasia and present as an introduced and invasive species in North America, where it was first noted in the Great Lakes region in 1843.[3]
Redshank is an annual herb with an erect rather floppy stem with swollen joints, growing to a height of 10 to 60 cm (4 to 24 in). The leaves are alternate and almost stalkless. The leaf blades often have a brown or black spot in the centre and are narrowly ovate and have entire margins. Each leaf base has stipules which are fused into a stem-enclosing sheath that is loose and fringed with long hairs at the upper end. The inflorescence is a dense spike. The perianth of each tiny pink flower consists of four or five lobes, fused near the base. There are six stamens, two fused carpels and two styles. The fruit is a shiny black, three-edged achene. This plant flowers from July to September.[4]
It is native to Europe and Asia, where it can be mistaken for Polygonum minus. The latter has narrower leaves, usually less than 1 cm wide. It has been introduced to North America and is naturalised throughout the mainland continent,[5] growing along roadsides, riverbanks, and on fallow ground. In the USA, it is very similar to Pennsylvania smartweed, but redshank has a fringe of hairs at the top of the ochrea, something which Pennsylvania smartweed lacks.
This plant contains persicarin and tannins. In medicine, Redshank is used against diarrhoea and infections. The leaves and young shoots may be eaten as a palatable and nutritious leaf vegetable. It is often seen as a weed and rarely cultivated. A yellow dye can be produced from this plant with alum used as a mordant.
(From Wikipedia on 8.1.14)


Persicaria maculata ABAUG2017/40 : 4 posts by 2 authors. Attachments (10)
These plants are shorter with more upright, denser, flower-spikes. The leaves have black markings. I think this is Persicaria maculata. Please advise.
Persicaria maculata?
Mcleodganj and above, Dharamshala, HP
1700m and above.
26 August 2017 and 03 August 2016 (fruit)

I think you are talking of Persicaria maculata S.F.Gray synonym for Persicaria lapathifolia subsp. lapathifolia (also available in efi) as per Catalogue of Life & not Persicaria maculata (Raf.) A. Löve & D. Löve (not available in efi).
I also think matches with images in efi at Persicaria lapathifolia

Ochrea looks different from Flora of North America illustration of Persicaria lapathifolia (L.) S. F. Gray.

You may be right about this being Persicaria maculosa Gray as per


Persicaria maculosa from Brampton Canada-22112022-1: 5 very high res. images.
Sharing Persicaria maculosa from Brampton, Canada growing on roadsides, clicked on