One of my earliest barefoot memories is stepping on a dead and dried stickerweed in the garden. They blend in so well with their surroundings that you don't see them until it is too late. 'Stickerweed' is the west Kentucky slang term for spiny amaranth, Amaranthus spinosus. Other names that readers may be familiar with are spiny pigweed or prickly amaranth. This South American native has spread world-wide and is a major agricultural pest. The sharp thorns make it unpalatable for grazing livestock and in parts of the world where weeding and harvest are still done by hand, it poses a major inconvenience. The sharp thorns are slow to decompose and I can personally attest that they can inflict mind-numbing pain long after the rest of the plant is compost.
Like all amaranths, it produces a huge amount of seed, sometimes over 100,000 per plant. Seeds germinate best with light, so tillage is a way to help control this annual invasive. They are often most abundant in fields that have been heavily grazed. Livestock tend to avoid this plant, however if forage is scarce, they may eat it out of desperation. While spiny amaranth is considered edible for humans, it is highly toxic to sheep, cattle and goats. The leaves can be cooked and eaten like spinach and there are many third-world peoples who depend on it as a food source. It is high in protein, beta carotene, potassium, calcium and iron. In fact, spiny amaranth has one of the highest concentrations of usable calcium known and is a great food for strengthening bones. The seeds are also nutritious and when ground, have more nutrients than traditional flours. It has been considered a 'famine food' by many, since it tolerates drought well and tends to prefer hard, compacted ground, making it one of the few plants available to people in stressed areas. It is even occasionally seen for sale in markets in third-world countries.
Spiny amaranth is also used in folk medicine. Its astringent properties have long been utilized for treating bleeding ulcers and diarrhea. The roots and leaves are also used to treat fevers, eczema, boils, snakebites and nosebleeds. Crushed plants and leaves are also effective in treating minor burns. Different parts of the plant are also used to make yellow, green and gray natural dye.
While this plant has a number of benefits, it is still quite a nuisance in gardens and agricultural lands. The best control is to stay ahead of seed production. The plants need to be taken from the garden completely since they often produce flowers right on the ground and can re-sprout from the roots. The seeds are also capable of maturing even after the plant has been chopped, so bag the plants and remove them from your garden. Do not add them to the compost bin since the seeds are quite capable of surviving high temperatures too. Seeds can remain viable for years, so consider this an on-going battle once the plants are established and remember to put on your shoes!