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primroseleaf horseweed
Scientific Name: Conyza primulifolia
Family: Asteraceae
Category: Dicot
Growth: Forb/herb
Duration: Annual, Perennial
Other Names:
Primrose-leaf Horseweed
This page provides information about Primrose-leaf Horseweed, a plant with a variety of characteristics and uses. Below are details compiled from several sources.
Considerations for Pets
- Historically, leaves of plants called "Fleabane" (including some types of Horseweed) were placed in pets' beds.
- The text mentions that it is not recommended to feed this plant to tortoises.
Considerations for Children
- Evening primrose stems have dense, spiral leaves.
- Horseweed leaves have sawtooth margins.
Scientific Name and Common Names
- Scientific Name: Conyza primulifolia
- Common Names: Primrose-leaf Horseweed, Horseweed (also sometimes called Canadian Fleabane, Mare's Tail, Dwarf Horseweed, Hogweed, Horseweed Fleabane, Mares)
Taxonomy and Nomenclature
- Family: Asteraceae (based on Canada horseweed, Conyza ramosissima and Missi evening primrose) and Primulaceae (Primrose Family)
- Synonyms: Conyza chilensis Spreng., Conyza chilensis var. carnea Chodat
- Additional Scientific Names Mentioned: Conyza canadensis (Horseweed), Oenothera biennis (Common Evening Primrose), Oenothera lanciniata (Cutleaf evening primrose), Primula veris, primula florindae, Calyptocarpus vialis (Sprawling Horseweed)
Distribution and Habitat
- Horseweed is found throughout California to about 6600 feet (2000 m).
- It inhabits waste areas, roadsides, and turf.
- Native to North America, it has spread throughout Europe, Africa, India, and the Middle East.
- Sprawling Horseweed (Calyptocarpus vialis) is native to Eastern regions.
Ecological Role
- Horseweed, along with cutleaf evening primrose, can be a troublesome weed, particularly in conservation tillage systems.
- Field studies have noted higher populations of horseweed and cutleaf evening primrose in cornfields that have little tilling and no cover crop.
- In certain countries, the plant has started to exhibit resistance to herbicides.
- Mentioned as an invasive plant species in Palau.
Morphological Characteristics and Growth Habits
- Horseweed is a summer annual or biennial broadleaf plant.
- Alternate leaves occur along the entire length of the stem, are densely arranged, and appear almost whorled.
- Horseweed leaves have sawtooth margins and a smooth texture.
- Evening Primrose produces a basal rosette of leaves in the first year.
- Some varieties have densely pubescent leaves that are deeply cut.
Interactions with Other Organisms
- Twospotted spider mites have been found on horseweed.
Traditional Uses
- Native Americans reportedly boiled the plant for steam in sweat lodges, used it as snuff for treatment of colds, and burned it to ward off evil.
- The plant has been used medicinally and in culinary applications.
- Horseweed has been called Fleabane because the leaves were historically placed in pets' beds.
- Stems, leaves, and flower buds are reportedly edible.
Resources and Further Information
- FAO's Ecoport Web Site
- PlantNet profile for Primrose-leaf Horseweed in New South Wales
- US Army Corp of Engineers (for management information)
- Center for Turfgrass Science