Arrowleaf Tearthumb, Scratchgrass, etc.
Synonyms: Helxine sagittatum (L.) Raf., Persicaria aestiva (Makino) Ohki, Persicaria belophylla (Litv. ex Grigorjev) Kitag., Persicaria sagittata f. paludosa (Kom.) H.Hara, Persicaria sagittata f. sericea (Nakai) H.Hara, Persicaria sieboldii (Meisn.) Ohki, Polygonum aestivum (Makino) Makino, Polygonum paludosum (Kom.) Kom., Polygonum sagittatum L., Polygonum sagittatum f. aestivum (Makino) Murata, Polygonum sagittatum var. boreale Meisn., Polygonum sagittatum var. gracilentum Fernald, Polygonum sagittatum var. ovalifolium Farw., Polygonum sagittatum subsp. sieboldii (Meisn.) Vorosch., Polygonum sieboldii Meisn., Tasoba sagittata (L.) Raf., Tracaulon sagittatum (L.) Small, Tracaulon sagittatum f. chloranthum (Fernald) Moldenke, Tracaulon sagittatum var. gracilentum (Fernald) C.F.Reed, Tracaulon sagittatum f. subalbidum Moldenke, Tracaulon sibiricum (Meisn.) Greene, Tracaulon sieboldii (Meisn.) Greene, Truellum aestivum (Makino) Soják, Truellum paludosum (Kom.) Soják, Truellum sagittatum (L.) Soják, Truellum sericeum (Nakai) Soják, Truellum sibiricum (Meisn.) Soják, Truellum sieboldii (Meisn.) Soják.
Persicaria sagittata (L.) H.Gross is the correct and accepted scientific name for the Arrowleaf Tearthumb. It was named and described as such by Hugo Gross in Beihefte zum Botanischen Centralblatt in 1919. This species was first named and described as Polygonum sagittatum by Carl Linnaeus in the first edition of Species Plantarum in 1753.
The genus, Persicaria (L.) 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 10-5-19). Those numbers will probably change.
For more information about Persicaria sagittata from the experts, please click on the links at the bottom of the page for further reading.
Persicaria sagittata (Arrowleaf Tearthumb) was one of the first species of wildflowers I identified on the farm when I returned in 2013. There is a swampy area in the southeast corner that I ventured into where there are many species of plants not found anywhere else here. That area has changed A LOT and now is mainly overgrown with Dichanthelium latifolium (Broad-Leaved Panic Grass. This summer I noticed the Persicaria sagittata has ventured to the area between the back pasture and the swamp that cannot be mowed where nature has gone wild.
Persicaria sagittata is by far the most interesting of the seven Persicaria species growing on the farm. It is a very easy species to identify with their arrow-shaped leaves. The largest leaves typically grow to 4″ long x 1″ wide that feels slightly rough because of the tiny hairs.
Terminal and axillary flowers are produced on short racemes with 1-10 flowers. Sometimes there are two racemes produced per leaf node on long peduncles up to 6″ long. A peduncle is a stem the flowers grow on. A raceme is an inflorescence with pedicellate flowers that grow at the end of the peduncle. One word leads to another… I can get more technical, but it is best you read it from the experts in the links provided below. Missouri Plants has a glossary of terms. 🙂
The species name comes from its sagittate leaves, meaning arrow-shaped.
As with all the Persicaria species here, the flowers consist of 5 sepals and no petals. I have only noticed white flowers, but they can also be pink.
The stems of Persicaria sagittata are actually square instead of being round like the other species here. The stems are covered with short retrorse prickles that point downward. Their stems can grow from 3-6 feet long and can climb on other plants. Stems laying on the ground can root at the leaf nodes. I only saw plants with green stems, but they can also be red or yellowish-green. Using the magnifying glass to get a close-up photo worked pretty good in the above photo. It takes practice and patience (and a lot of photos).
The above photo taken on September 22 is froma colony I had just discovered. The many plants were sprawling on the ground are through other vegetation. You can see how they branch out at the nodes.
I took a SERIES of photos to show what the bottom side of the flowers look like but that didn’t work out so well. 🙂 Practice makes perfect.
I really enjoyed photographing and identifying the seven species of Persicaria on the farm. I wrote a post called Perplexing Persicaria with links to pages for each species.
I will continue adding more photos and information as time goes by.
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.
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 firstname.lastname@example.org. I would enjoy hearing from you.