Spiny Amaranth, Spiny Pigweed, Thorny Pigweed, Needle Burr
Synonyms of Amaranthus spinosus (4) (Updated on 9-30-21 from Plants of the World Online): Amaranthus caracasanus Kunth, Amaranthus coracanus Mart., Amaranthus diacanthus Raf., Galliaria spitosa (L.) Nieuwl. Other databases show up to 15 synonyms.
Amaranthus spinous L. is the correct and accepted scientific name for this species of Amaranthus. The genus and species were described by Carl von Linnaeus in the second edition of Species Plantarum in 1753.
Plants of the World Online by Kew lists 93 species in the Amaranthus genus (as of 9-30-21 when I last updated this page). It is a member of the plant family Amaranthaceae with 186 genera. Those numbers could change as updates are made.
The above distribution map for Amaranthus spinosus is from Plants of the World Online. Areas in green are where the species is native and purple is where it has been introduced. The map on the USDA Plants Database is similar but shows the species to be a U.S. and Canadian native rather than it being introduced.
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. Maps on iNaturalist are updated continually as observations are added by members.
THERE ARE A FEW LINKS AT THE BOTTOM OF THE PAGE FOR FURTHER READING AND TO HELP WITH BETTER POSITIVE ID.
Amaranthus spinosus is definitely one of those plants you love to hate. I remember my grandpa digging them on here on the farm when I was a kid. There are several weeds that it is nearly impossible to eliminate and this is one of them. They are a never-ending battle because not only do they produce a lot of seed (around 100,000 per plant), but their seeds remain viable for many years. Their seeds need light to germinate, so tilling the soil is one good way to help control them. I don’t like this species growing anywhere on the farm, but I really don’t like them in the garden. I pull weeds by hand but that is hard to do with this plant because of their thorns.
Once you have this plant in your garden or in your pastures, you will easily be able to recognize it. It is definitely not one that you will forget.
Once you have it, you will be more concerned with getting rid of it. That is not easy to do because there are always more to come.
Interesting that such a plant as this so detested by many is actually edible and eaten by many in some countries. It is very nutritious and has one of the highest concentrations of useable calcium. Even though it may be nutritious, I think I will not be eating any part of this plant.
Melody Rose has published an interesting article on Dave’s Garden you may be interested in reading.
I have enjoyed photographing and learning about the many wildflowers growing on the farm and other areas. My farm is in Windsor, Missouri in Pettis County (Henry County is across the street and Benton and Johnson aren’t far away). 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 few horticulturalists 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. Some sites may not be up-to-date but they are always a work in progress. 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 especially if you notice something is a bit whacky
FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
INTERNATIONAL PLANT NAMES INDEX (GENUS/SPECIES)
FLORA OF NORTH AMERICA (GENUS/SPECIES)
WORLD FLORA ONLINE (GENUS/SPECIES)
MSU-MIDWEST WEEDS AND WILDFLOWERS
USDA PLANTS DATABASE
LADY BIRD JOHNSON WILDFLOWER CENTER
PFAF (PLANTS FOR A FUTURE)
NOTE: The figures may not match on these websites. It depends on when and how they make updates and when their sources make updates (and if they update their sources or even read what they say). 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. In my opinion, Plants of the World Online by Kew is the most reliable and up-to-date plant database and they make updates on a regular basis. I make updates at least once a year and when I write new pages but I do get behind. We are all a work in progress. 🙂