This is one of two widespread, weedy species of Galinsoga, either Gallant Soldier (G. parviflora) or Shaggy Gallant Soldier (G. quadriradiata). The hairs seen on the leaves are suggestive of the latter species, but observation of reliable distinguishing characters requires a close examination of the inflorescence receptacle and cypselae (seeds).
The genus Galinsoga in the Milleria tribe (Millerieae) of the Daisy Family (Asteraceae), is native to tropical and subtropical areas of the New World, but the two species listed above are now cosmopolitan weeds.
There are references to be found online claiming edible and medicinal uses for this plant, but caution and thorough research should be practised before consuming any unfamiliar plant.
The common name, 'Gallant Soldier' is a curious example of a common name being created as a mnemonic for the scientific name.
