Oriental Lady’s Thumb, Bristly Lady’s Thumb, Asiatic Smartweed, Creeping Smartweed, Long-Bristled Smartweed, Low Smartweed, Asiatic Waterpepper, Bristled Knotweed, Bunchy Knotweed, Tufted Knotweed

Persicaria longiseta

(Persicaria longiseta var. longiseta)

per-sih-KAR-ee-uh 

Synonyms of Persicaria longiseta (4) (Updated on 12-22-23 from Plants of the World Online): Persicaria cespitosa var. longiseta (Bruijn) C.F.Reed, Polygonum cespitosum var. longisetum (Bruijn) Steward, Polygonum longisetum Bruijn, Polygonum posumbu var. longisetum (Bruijn) F.Z.Li & C.Y.Qu
Synonyms of Persicaria longiseta var. longiseta (22) (Updated on 12-22-23 from Plants of the World Online): Persicaria blumei (Meisn.) Nakai (1919), Persicaria blumei var. albiflora Honda (1931), Persicaria buisanensis (Ohki) Sasaki (1928), Persicaria erectominor var. roseoviridis (Kitag.) I.Ito (1956), Persicaria gentiliana H.Lév. (1914), Persicaria longiseta var. albiflora (Honda) Honda (1939), Persicaria longiseta f. albiflora (Honda) Masam. (1954), Persicaria longiseta f. brevifolia (Makino) Hiyama (1962), Persicaria longiseta f. breviseta (Meisn.) W.Lee (1996), Persicaria longiseta f. divaricatiramosa Hiyama (1962), Persicaria roseoviridis Kitag. (1937), Persicaria satsumensis Nakai (1950), Polygonum blumei Gand. (1919)(nom. illeg.), Polygonum blumei Meisn. (1865), Polygonum blumei var. brevifolium Makino (1913), Polygonum blumei var. contractum Makino (1914), Polygonum buisanense Ohki (1925), Polygonum donii var. tenerum Meisn. (1832), Polygonum gentilianum (H.Lév.) H.Lév. (1916), Polygonum interruptum Bunge (1833), Polygonum longisetum f. albiflorum (Honda) Ohwi (1953), Polygonum roseoviride (Kitag.) S.X.Li & Y.L.Chang (1959)

Persicaria longiseta (Bruijn) Kitag. is the accepted scientific name for this species of Persicaria. It was named and described as such by Masao Kitagawa in the Report of the Institute of Scientific Research (Manchoukuo) in 1937. It was first named and described as Polygonum longisetum by Ary Johannes de Bruijn in Plantae Junghuhnianae in 1854.

Accepted infraspecific names of Persicaria longiseta (2) (Updated on 12-22-23): *Persicaria longiseta var. longiseta (autonym), Persicaria longiseta var. rotundata (A.J.Li) B.Li. *When an infraspecific taxon is named, an autonym (“type-specimen”) is automatically generated whose description is closest to the (original) species. All have their own list of synonyms.

The genus, Persicaria Mill., was named and described as such by Philip Miller in the fourth edition of The Gardeners Dictionary in 1754. Many species in the Polygonum genus were transferred to the  Persicaria genus after that.

As of 12-22-23 when this page was last updated, Plants of the World Online lists 130 species in the Persicaria genus. It is a member of the plant family Polygonaceae with 56 genera. Those numbers could change as updates are made by POWO.

The above distribution map for the Persicaria longiseta is from Plants of the World Online. and includes the infraspecific species. Areas in green are where the species is native and purple is where it has been introduced. The map on the USDA Plants Database for North America for the species is somewhat different and they also use the scientific name Persicaria cespitosum var. longisetum… POWO says that name is a synonym of Persicaria longiseta and the USDA says P. longiseta is the synonym… Anyway, the species could be more widespread than the maps show.

The map on iNaturalist shows where members have made observations. Anyone can join and it is a great website to confirm and share your observations. The maps on iNaturalist are continually updated as members post new observations.

Persicaria longiseta isn’t a native of North America although it has made itself quite at home. One website says it is only 20% likely the species grows here, but I can tell you without hesitation, that this species is 100% alive and well from one end of the farm to the other.

THERE ARE A FEW LINKS AT THE BOTTOM OF THE PAGE FOR FURTHER READING AND FOR A BETTER POSITIVE ID.

When I decided to identify all the Persicaria species growing on the farm I took my camera and took photos of all the colonies in the pasture behind the chicken house and south of the barn. A few days later I noticed this colony next to the shed in the backyard where my grandparent’s house was. It appeared to be the same species that always grows under the porch on the north side of the house and the flower bed there. I usually take photos in the afternoon then look them over and make positive identifications in the evening. As I was trying to ID this colony they appeared to be Persicaria longiseta but I needed to look at their flowers again to make a positive ID. The flowers in the above photo didn’t show me what I needed to know so I went out with the flashlight and magnifying glass (in my boxer shorts) to have a look… Sure enough, the colony is Persicaria longiseta.

Two very important things distinguish Persicaria longiseta from the other six species that are growing here on the farm. You have to read farther down to when I took photos of those special characteristics.

As with “most” Persicaria species, they have fairly dark green lance-shaped leaves. The leaves of Persicaria longiseta are normally around 3″ long although the longest I have measured is 4″. Information online says their leaves are alternate with short petioles (the small stem between the leaf and stem of the plant), elliptic, broadly lanceolate or ovate, smooth along the margins, and hairless.

The stems are light green to reddish-brown, glabrous, and send stems out usually from the lower nodes. They are decumbent in growth habit which means they sprawl out on the ground and stand up toward the end. Information online says they grow as long or tall, depending on how you look at it, to 36″ or more.

Ahhh. One of the two distinguishing features of Persicaria longiseta is the cilia growing from the ocrea (sometimes spelled ochrea). The ocrea is basically a sheath that grows at the base of the leaf around the stem and above the node (joint). The cilia look kind of like hair or bristles. The cilia seem to stay attached with P. longiseta while they typically fall off of other species. Even the ocrea dries and falls off of some species.

Another photo of the cilia growing from the ocrea of P. longiseta. The ocrea on Persicaria species is nearly translucent and is formed by the fusion of two stipules. One word seems to lead to another… A stipule is formed at the base of a petiole. Hmmm…

I found more Persicaria longiseta growing along the bank of the pond in the back of the farm on September 4. From a distance, P. longiseta looks very similar to P. setacea and both do have cilia on their flowers and ocrea. However, P. setacea also has horizontal hairs growing from the sides of their ocrea. I was hoping for that because P. setacea is fairly rare, especially around here as in nonexistent… They grow in the southeast corner of Missouri.

The above photo is a good shot of the cilia growing on the flowers of P. longiseta. The cilia are actually growing from a sheath at the base of each flower.

Sometimes I have no words…

I just take a lot of photos so I can make a positive ID later.

 

I found a larger colony of Persicaria growing behind the pond bank at the back of the farm on September 9. Sometimes I am on a “mission” and don’t take the time to look around.

Another photo of P. longiseta behind the pond bank.

Another close-up…

 

With age, some of the cilia may fall off of the flowers.

 

 

There is a HUGE colony of Persicaria longiseta in front of a couple of large Mulberry trees in the front pasture. Some of their racemes look a little weird…

Hmmm…

More bristly ocrea…

There is always a colony of P. longiseta under the porch on the north side of the house. They like to escape into the flower bed…

Here is a colony along the shed behind the garage.

Here is a leaf with a nice thumbprint…

The tiny seeds of Persicaria longiseta are black and shiny. The seeds of all Persicaria species are black and shiny except for P. hydropiper which are black to brownish and dull (not shiny). Maybe I shouldn’t say ALL, but that is what I read somewhere.

 

Nice 4″ long leaf with a faint smudge.

The above photo is P. longiseta with P. punctata next to the twin Mulberry trees in the front pasture.

The above photo shows the glabrous stems of P. longiseta branching out t the lower nodes. This single plant was 42″ long, or tall…

Another photo of P. longiseta behind the pond at the back of the farm. In time, new flower stems grow from the upper leaf nodes.

Another shot of the same plant.

Good photo with a lot of hair… You can also see light hairs on the leaf. I get my close-ups using a magnifying glass in front of the lens. It takes patience and A LOT of practice.

Hmmm… I think this photo is a colony in front of the Mulberry trees in the front pasture.

And another area in front of the Mulberry trees.

This whole area in front of the Mulberry trees in the front pasture is full of Persicaria longiseta mingled with P. punctata. You can see the pink glow. There are a few P. pensylvanica mixed with P. punctata around the trees in a few areas. This area slopes toward a low spot (kind of a ditch) where the pond in the front pasture drains in. On the other side of the ditch, close to the pond, P. hydropiper is king.

I mentioned previously Persicaria longiseta grows under the porch and in the flower bed on the north side of the house… Here it is mingling with the Salvia coerulea ‘Black and Blue’ on September 30.

Persicaria longiseta is growing everywhere on the farm that is a good habitat for them. I am finding them in more places all the time…

I enjoyed the experience of 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 family farm and in other areas. I have grown over 500 different plants and identified over 250 species of wildflowers (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.

I hope you found this page useful and be sure to check the links below for more information. They were written by experts and provide much more information. If you can, I would appreciate it if you would click on the “Like” below and leave a comment. It helps us bloggers stay motivated. You can also send an email to me at thebelmontrooster@yahoo.com. I would enjoy hearing from you.

FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
INTERNATIONAL PLANT NAMES INDEX (GENUS/SPECIES)
TROPICOS (GENUS/SPECIES)
FLORA OF NORTH AMERICA (GENUS/SPECIES)
WORLD FLORA ONLINE (GENUS/SPECIES)
USDA PLANTS DATABASE (SYNONYM)
WIKIPEDIA (GENUS/SPECIES)
MISSOURI PLANTS
iNATURALIST
WILDFLOWER SEARCH
ILLINOIS WILDFLOWERS
MINNESOTA WILDFLOWERS
GO BOTANY

NOTE: The data (figures, maps, accepted names, etc.) may not match on these websites. It depends on when and how they make updates and when their sources make updates. Some websites have hundreds and even many thousands of species to keep up with. Accepted scientific names change periodically and it can be hard to keep with as well. Some of the links may use a name that is a synonym on other sites. In my opinion, Plants of the World Online by Kew is one of the most reliable and up-to-date plant databases and they make updates regularly. I make updates “at least” once a year and when I write new pages or add new photos but I do get behind. We are all a work in progress. 🙂