This is a weedy hexaploid (2n = 60) up to 2 m tall that is widely scattered across temperate North America, but rare to absent in southeastern states (K). The plant appears to have been used for its edible seed during the Woodland era (Ford 1985), and it was reported from pond sediments of similar age in LARU (Wilkins 1985). But see also notes under prolificum, which is closely related. FNA 5 reported typical ramosissimum from Ky., but almost no colls. have been located with confirmed identification (M). There is a suggestive immature coll. from OLDH (DHL), and a sight record from TRIM (M); but these records may refer to prolificum instead. There does appear to be a reliable recent report from HICK in iNaturalist by V. Voelcker (NP). P. ramossissimum (sensu stricto) is reported to differ from prolificum as follows (FNA 5, W): plants yellowish green when fresh (versus bluish green), not darkening when dried (versus turning dark brown to black in patches); leaves acute to acuminate at apex (versus rounded to obtuse); pedicels 2.5-6 mm long (versus 1-2 mm); leaves heterophyllous, on stems 2.1-3.5 (-4.2) times as long as the branch leaves (versus homophyllous, 1-2.5 (-3.5) times).