Conyza ramosissima, the dwarf horseweed, is a species of North American plants in the family Asteraceae. It is widespread and common across the central part of the United States, its range extending from New Mexico east to Alabama and north as far as Pennsylvania, Ontario, and North Dakota.Biota of North America Program 2014 county distribution map, Erigeron divaricatus
The oldest name for the species is Erigeron divaricatus, coined in 1803Michaux, André 1803. Flora Boreali-Americana 2: 123 in Latin and still used by some sources. Moving the species to Conyza required a change in epithet to avoid a conflict with the name Conyza divaricata Spreng., used for a South American plant in 1826.Sprengel, Curt Polycarp Joachim. 1826. Systema Vegetabilium, editio decima sexta 3: 508 in Latin Hence the new name Conyza ramosissima.Cronquist, Arthur John 1943. Bulletin of the Torrey Botanical Club 70(6): 632
Conyza ramosissima is a much-branching annual herb sometimes growing to a height of 25 cm (10 inches) or more. Its leaves are small and thread-like. It has numerous small flower heads, each with white or lavender ray florets and yellow disc florets. The plant is most often found in disturbed sites such as fields, roadsides, etc.Flora of North America, Conyza ramosissima Cronquist
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