Iva annua

Iva frutescens (marsh elder) is similar but has lance shaped leaves and is a shrub rather than a forb. May also be confused with Baccharis halimifolia which has alternate leaves and teeth along the margins of the leaf only near the tip end (I. annua and I. frutescens have opposite leaves and teeth along the entire margin). Not woody. Opposite leaves. Wide leaves and hairy stems. Some upper leaves alternate but chiefly opposite.

Very unpalatable to cattle.

A warm-season, robust weed, with a fibrous root system, and which reproduces by seed. It is often abundant in ditches and waste places and its pollen is a major contributor to hay fever and allergy suffering. It is most common in wet areas on clay soils but may be present in other habitats. It is unpalatable to livestock and is a weedy pest of low-vigor pastures and overgrazed range. It is found in Texas, Louisiana, Missouri, Oklahoma, Kansas and Nebraska and is thought to be spreading to other areas (Philips Petroleum Company 1956). The seeds of this species have been found stored in caves along with other edible seed leading scholars to believe that the seeds were once used as food. The seeds found were larger than modern Iva seed, indicating that some selection was occurring. Little is known about how native Americans used these seeds, and its use as food is not recommended.

Fields and freshwater marshes.