Spiny Pigweed

Biological Name:

Amaranthus spinosus (Spiny-Pigweed)

Natural Habitat:

Spiny-Pigweed: The spiny-pigweed grows in areas with warm, dry conditions, such as fields and roadsides. It is commonly found in North America.


Spiny-Pigweed also known as Amaranthus is a plant that is native to grassland and prairie regions of North America. It is an annual herb that can grow up to six feet tall and it has small oval-shaped leaves and small inconspicuous flowers that are typically green or yellow in color. The plant is known for its sharp spiny leaves and it is often found in disturbed or degraded habitats.

Frequently Asked Questions (FAQs)

Q: Can I eat spiny amaranth?
A: The leaves and stems of Amaranthus spinosus are eaten raw or cooked as a spinach. Remove the spines in older plants. Seed are easy to harvest and very nutritious.

Q: Why was amaranth outlawed?
A: In the 16th century the Spanish conquistadors banned the plant’s cultivation, fearing that the spiritual connection with it would stymie the establishment of Catholicism on the continent. But the Incas and Mayans continued to grow amaranth.

Q: What happens if you eat raw amaranth?
A: Amaranth cannot and should not be eaten raw. While there are no known toxicities associated with this grain, cooking it is essential. It has anti-nutrients. Most grains contain anti-nutrients like oxalates and phytates which can bind to vitamins and minerals, leaving them unavailable to your body.

Q: What are the side effects of amaranth?
A: Side-Effects & Allergies of Amaranth Grain For people with intolerance to lysinuric protein, eating amaranth may cause diarrhoea and stomach pain. Moreover, another side effect of lysine increase body’s calcium absorption, and bring free, damage-causing amount of calcium in the body.

Q: Can you eat amaranth without cooking it?
A: We can’t digest raw amaranth. It’s like eating raw rice or raw beans. It’ll pass right through our digestive tract without change. It’s necessary to either cook it or puff it so we can digest it and enjoy the benefits of this amazing superfood.

Q: What kills spiny amaranth?
A: Growth regulator herbicides such as dicamba or picloram are effective at controlling spiny amaranth, but will also injure or kill any legumes in the pasture. Mowing before the plant reaches maturity can suppress seed production, but even damaged plants may recover and produce seeds.

Q: What are the benefits of eating amaranth?
A: Amaranth is a nutritious, gluten-free grain that provides plenty of fiber, protein and micronutrients. It has also been associated with a number of health benefits, including reduced inflammation, lower cholesterol levels and increased weight loss.

Q: Should I remove pigweed?
A: If you spot pigweed plants that have yet to produce mature seeds, pull them or cut them off just below the soil line. Plants with mature seeds should be bagged before being removed and destroyed. Either burn the plants or bury them under at least a foot of compost.

Q: How do you control spiny pigweed?
A: Mowing can suppress spiny pigweed seed production, but even beat-up plants can still occasionally produce seed. Applying products with dicamba (at a rate of 1 lb ai/A) or Crossbow® (2 to 4 qt/A) are effective at controlling spiny pigweed. Crossbow® can also be applied as a spot treatment (1-1.5% v/v).

Q: Does pigweed come back every year?
A: Prostrate pigweed — AKA mat amaranth, prostrate amaranth or spreading pigweed — is a summer annual that acts like a perennial. Although it completes its life cycle in one growing season, it can come back year after year, seemingly resisting any attempts to eradicate it.

Q: What does pigweed tell you about your soil?
A: Redroot pigweed (Amaranthus retroflexus) indicates that the soil is heavily compacted by either heavy foot traffic or just high clay content. Compaction is a sign of low aeration, meaning lower oxygen for roots, soil microbes, water logging and undeveloped root system.

Q: What is the difference between amaranth and pigweed?
A: It is also known as Palmer pigweed. Palmer amaranth is related to other pigweeds in our region including redroot, smooth, Powell, and spiny, but unlike these other pigweeds, Palmer amaranth grows faster and is dioecious, meaning that plants are either male or female.

Q: Why is pigweed so difficult to control?
A: The researchers have determined a specific genetic feature, the extrachromosomal circular DNA (eccDNA) replicon, gives pigweed, or glyphosate resistant palmer amaranth, its resistance to glyphosate and makes this weed difficult to control.

Q: Is amaranth toxic?
A: Avoid eating too much amaranth from agricultural fields. The leaves (like those of spinach, sorrel and many other greens) also contain oxalic acid, which can be poisonous to livestock or to humans with kidney issues of eaten in large amounts.

Q: What are the benefits of pigweed?
A: The leaves of pigweed are also incredibly nutritious. They’re high in vitamins A and C and folate, as well as calcium. In Jamaica, pigweed is known as callaloo and is a culinary staple.

Q: Can you eat spiny pigweed?
A: People in Mozambique eat spiny pigweed leaves as a wild plant foodstuff — the leaves have been reported to be a good protein source. Although considered edible, it should be noted that there are some potential problems with pigweeds. Pigweeds have been associated with nitrate accumulation in livestock.

Q: Is pigweed poisonous to humans?
A: Yes, the weeds in the garden we call pigweed, including prostrate pigweed, from the amaranth family, are edible. Every part of the plant can be eaten, but the young leaves and growing tips on older plants are the tastiest and most tender. The seeds are nutritious, edible, and are not difficult to harvest.

Q: Why do they call it pigweed?
A: Their common name, pigweed, may have comes from its use as fodder for pigs. Pigweed plants are commonly considered to be weeds by farmers and gardeners because they thrive in disturbed soils.

Q: Can you eat raw pigweed?
A: Pigweed can grow to 2-3 metres high and are generally found in gardens, cultivated or abandoned fields. The leaves can be eaten raw or cooked like spinach, due to its mild flavour, it is adaptable to many dishes.

Q: What part of pigweed is poisonous?
A: Pigweed (Amaranthus retroflexus) is a common annual weed found throughout the United States. The weed can grow three to four feet; the flowers are green and prickly and the plant has oval shaped leaves. The pigweed’s leaves, roots and stems are toxic.

Q: What damage does pigweed do?
A: Gross lesions of pigweed toxicosis include widespread edema, most prominently around the kidneys, rectum and omentum. Kidneys are pale and normal to swollen in size. Histopathologic changes within the kidney include interstitial edema, scattered hemorrhages and proximal tubular degeneration and necrosis.

About the author

Samuel is a gardening professional and enthusiast who has spent over 20 years advising homeowners and farm owners on weed identification, prevention and removal. He has an undergraduate degree in plant and soil science from Michigan State University.