Conyza spp. (butterweeds or horseweed)
Pulicaria spp. (false fleabane), especially common fleabane (Pulicaria dysenterica subsp. dysenterica, formerly Inula dysenterica)
Erigeron spp., especially Erigeron acre (blue fleabane)
Inula spp. (yellowheads)
Also, in subfamily Cichorioideae, Vernonia spp. (ironweeds).
mostly in two tribes of subfamily Asteroideae
Pluchea spp. (camphorweeds)
Erigeron canadensis (syn. Conyza canadensis), an annual weed
especially, common mare's tail (Hippuris vulgaris)
Equisetum, a fern ally
A long streaky cloud, spreading out like a horse's tail, and believed to indicate rain; a cirrus cloud.
Any aquatic plant of the genus Hippuris, having narrow leaves in whorls.