Lady’s Thumb, Redshank, Heart’s Ease, Heartweed, Spotted Knotweed
Synonyms: Persicaria dolichopoda (Ohki) Nakai, Persicaria fallax Greene, Persicaria fusiformis (Greene) Greene, Persicaria granulata Greene, Persicaria incana Gray, Persicaria interrupta Gray, Persicaria mitis Delarbre, Persicaria opaca (Sam.) Koidz., Persicaria persicaria (L.) Small, Persicaria pusilla Gray, Persicaria rivularis Opiz, Persicaria salicifolia Gray, Persicaria vulgaris Webb & Moq., Peutalis persicaria (L.) Raf., Polygonum biforme Wahlenb., Polygonum fusiforme Greene, Polygonum opacum Sam., Polygonum persicaria L., Polygonum persicaria var. angustifolium Beckh., Polygonum praelongum Gand., Polygonum vernum Raf.
Persicaria maculosa Gray is the correct and accepted scientific name for the Lady’s Thumb. It was named and described by Samuel Frederick Gray in Natural Arrangement of British Plants in 1821. Persicaria maculosa var. amblyophylla is currently the only accepted variety of P. maculosa listed by Plants of the World Online and are native of Japan. POWO list 19 synonyms of the species including Polygonum persicaria which is one of the most common.
The genus, Persicaria Mill., was named and described by Philip Miller in the fourth edition of Gardener’s Dictionary in 1754. According to Plants of the World Online by Kew, there are currently 129 accepted species in the genus Persicaria (as of when I am writing this page on 9-23-19). Many species of Persicaria were transferred from the Polygonum genus.
The above distribution map is from Plants of the World Online by Kew and is current as of October 11, 2019. The green is where they are native and the purple is where they have been introduced.
Out of seven species of Persicaria on the farm, there are fewer P. maculosa than any. When I started photographing the Persicaria species to make proper identification in 2019, I noticed their numbers had dropped to just a small colony in front of the Mulberry trees in the front pasture. I had taken photos since 2013 that are labeled Persicaria maculosa, but I didn’t know as much about their characteristics then so they may have been P. longiseta instead (they rank #2 in population).
Racemes of flowers are normally around 1 1/2″ long (more or less) sometimes with small “auxiliary” racemes at the upper leaf nodes and even possibly lower nodes as well. Their small flowers include 5-6 sepals and usually six stamens, and no petals. Flower color is usually shades of pink but can be reddish, greenish-white, or purple even on the same raceme. Flowers are shy, so if you see a few open you are lucky. Persicaria maculosa flowers do not have cilia (hairs) like P. longiseta, nor do they have “punctate glandular dots” like P. hydropiper and P. punctata. So, if you see hair on the raceme or glandular dots on the flowers, you do not have P. maculosa.
While typically shorter, their leaves can grow up to 6″ long x 1″ wide. Persicaria maculosa are decumbent, which means their stems typically sprawl on the ground and turn upward. So, their stems are usually longer than they appear. As with most Smartweeds, they are multi-branching.
The translucent ocrea (sometimes spelled ochrea) around the leaf node can have a few bristles but may fall off with age. Here you can see a few branches starting to emerge. Stems are usually a dark reddish-green and more reddish at the nodes.
The alternate leaves are up to 6″ long and 1″ across, although usually smaller. They are lanceolate or linear-lanceolate, hairless, smooth along the margins, and sometimes slightly ciliate. Each leaf has a short petiole or it is nearly sessile (no petiole). The leaves are kind of dark green with lighter areas and MAY have a dark spot as in the third photo above.
Hmmm… I pulled this stem to show how long they can get, but looking back I don’t think I should have done that. At the time I didn’t realize this small colony in front of the Mullberry trees was the only area they were growing… The Persicaria in the background is a mixture of Persicaria longiseta and Persicaria punctata.
The above photo is a good example of longer and shorter leaves on the same plant. This is kind of common with Persicaria species (and most plants in general). You can also notice the color of the leaves and stems pretty well in this photo.
There are a few key features to help you identify Persicaria maculosa. 1) their racemes are kind of “blunt” on top rather than looking more pointed (especially from a distance”. 2) Flowers of different colors on the same raceme (shades of pink, red, greenish-white, purplish). 3) NO glandular dots on the flowers. 4) No cilia on the flowers. 5) Sometimes the ocrea around the leaf nodes on the stems have bristles (cilia) but not necessarily. 6) Dark leaves UP TO 6″ long but usually shorter, with sometimes a dark spot in the center of the leaf. But not always. In short, typically a pink-flowered plant with kind of blunt inflorescences. Flowers have no hair and some of the leaves may have a dark spot resembling a thumbprint.
Persicaria species are very interesting once you realize their uniqueness. Most species flowers rarely open and appear to always be buds. However, they are not only self-pollinating, but they can also pollinate without opening. Most flowers pollinate after they open.
Persicaria maculosa seeds are small, black, and shiny. You may be thinking, “duh!” But not all Persicaria seeds are black and shiny. A few species have dull brownish seeds.
On September 22 when I took the above photo, it appears the flowers of the Persicaria maculosa are beginning to dry. One weird thing about Persicaria species is that even long before the flowers dry they already have seed. One seed per flower.
I enjoyed the experience identifying the seven species of Persicaria growing on the farm. You can read the post about them all by clicking HERE where you will also find links to their own pages.
I have enjoyed photographing and learning about the many wildflowers growing on the farm and other areas. I have grown over 500 different plants and most have pages listed on the right side of the blog. I am not an expert, botanist, or horticulturalist. I just like growing, photographing and writing about my experience. I rely on several websites for ID and a horticulturalist I contact if I cannot figure them out. Wildflowers can be somewhat variable from location to location, so sometimes it gets a bit confusing. If you see I have made an error, please let me know so I can correct what I have written.
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