Potent allergen. Pigweed is a weed, from a plant family with a latin name is amaranthus. The pollen of this plant is very potent to induce allergic disease. People exposed to pigweed develop allergy to pigweed pollen easier than to other weed pollen, similar to ragweed pollen. They suffer from allergic respiratory symptoms, especially during the fall.
Pigweed. If you search pigweed on the internet you can find lots of nice pictures. It is often the second most important weed allergen in many states. It blooms in the fall, typically at the same time ragweed is blooming. (typically the most important weed pollen).