Amaranth/Pigweed is one of dozens of the most common urban weeds included in POP’s Weed Identification Guide, which is available for order through our website.
I must have seen amaranth a thousand times, as an easily-pulled seedling in my vegetable garden—but I never really noticed it until I stepped onto an organic farm in early fall and beheld a true monster. A weed it may still have been, but now it was almost my height, and tenaciously hard to uproot.
The genus Amaranthus has produced excellent food crops, lovely ornamental plants, and some of agriculture and horticulture’s most pernicious weeds. Native to South and Central America, plants in this genus (amaranths) have spread around the world, making their way into Korean side dishes, Mexican candies, and Jamaican callaloo. Some amaranth plants, such as Love-Lies-Bleeding (Amaranthus caudatus) are cultivated as ornamentals. The amaranth plants that turn up as weeds in farms, orchards and just about everywhere else are often collectively known as pigweed, although one (A. tuberculatus/A. rudis) is more often called common waterhemp.
Because there are more than 70 species of amaranth and there isn’t a lot of difference between them, it may be enough functionally to identify the plant as amaranth. Two of the most common weedy species are Amaranthus retroflexus (common or redroot amaranth), and A. palmeri (Palmer amaranth, native to southern North America). Both are short-lived, annual, herbaceous plants, but if left alone they can grow taller than 3 meters and become somewhat woody. They send down a tough taproot, especially in tilled soil. Redroot gets its name from the red base of the stem, although this isn’t unique to that species. Palmer amaranth is considered a very dangerous weed, especially in the southern United States, where it threatens the cotton and soybean industries—it evolves fast, and has become resistant to many herbicides, including RoundUp.
Pigweed can grow very fast in full sun, but in the shade of an established orchard it shouldn’t be as much of a threat. However, amaranths seed prolifically—palmer amaranth, for example, can produce hundreds of thousands of seeds per plant.
How do I recognize amaranth?
Amaranth is pretty easy to recognize once it starts flowering. The flower spikes are long and tapering and often bunched at the top of the plant. It looks like something out of Dr. Seuss. The individual flowers are prickly-looking, tightly packed together, and usually range from green to red in color. Later, these clusters will bear thousands of tiny brown or black seeds, which may or may not start falling off the plant prodigiously in late summer, dropping out of their hidden dens in the chaff of the flowers. Some amaranth species are dioecious—meaning that a plant will be male or female—with the female plant often much bigger and hardier.
Of course, if your aim is control rather than aesthetic appreciation, you probably don’t want to wait until it flowers. Depending on species and the specific plant, the leaves may be anything from oval to paddle-shaped to diamond-shaped; often, they end up looking something like a spear tip. That impression is enhanced by the fact that the plant thrusts its leaves out from the stem on long “petioles”—leaf-stems—that in some species like Palmer amaranth can be longer than the leaf itself. The leaves are all singular, not bunched, and spaced widely so they catch as much light as possible. This is a plant out for every edge it can get. This leaf spacing pattern shows in the youngest seedlings, and in some species those seedlings also have a notched tip, making them easy to identify and pull up if you want to get rid of them before they get too big. Older leaves may be smoothish or hardy and somewhat hairy.
Can I eat this?
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Cultivated amaranth seeds are white, while the wild varieties tend to be black. It’s unclear whether this affects the edibility of the seeds—the wild seeds are difficult to harvest except at very specific times of year, and it’s hard to separate the thousands of tiny grains from the chaff. Unless you have a lot of time or dedicated equipment, it’s probably not worth trying to make a meal out of amaranth seed.
The leaves are still edible, though—with some caveats.
Amaranth tends to collect nutrients in its environment, especially nitrates, and if it’s in a heavily fertilized area these nitrates can accumulate to the point of being bad for your health. 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. You shouldn’t eat any amaranth (or any other plant) you find growing in an environment that could be contaminated with toxins like heavy metals or that may have been sprayed with any kind of pesticide or herbicide. Combined, those restrictions eliminate most amaranth plants growing in urban, roadside, agricultural and horticultural environments, as well as many gardens. Depending on the use of sprays or herbicides, you may or may not be able to eat the amaranth you find growing in your POP orchard. If you’re in a chemical-free orchard that’s far from sources of contamination, you can probably feel free to enjoy amaranth as an occasional or common side dish, depending on how nitrate-rich the soil is, while you’ll likely want to avoid those growing in commercial orchards that use some forms of herbicides or pesticides.
If you plan to eat amaranth, get it while it is still young and tender—coincidentally, also the time that makes the most sense for weed control. The plant is robust and tough once it gets older, and hard to wrangle once those seeds develop. Get it early and boil it up like spinach—or just throw it on the compost pile. But even if you don’t eat it, give this plant a hand for its extraordinary survival abilities, adaptive nature, and its roles in human societies throughout history.
This POP Plant Feature was written by volunteer blog contributor Katie Pflaumer. Katie Pflaumer is a writer, editor and legume enthusiast with interests in ethnobotany, edible wild plants, and the uses of agriculture and horticulture to build just and sustainable societies.
The Philadelphia Orchard Project stresses that you should not consume parts of any wild edible plants, herbs, weeds, trees, or bushes until you have verified with your health professional that they are safe for you. As with any new foods that you wish to try, it is best to introduce them slowly into your diet in small amounts.
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