Noun
Any of several plants, not closely related, that produce many seeds, such as
allseed flax (Radiola linoides)
fourleaf allseed (Polycarpon tetraphyllum)
knotweed (Polygonum spp.)
many-seeded goosefoot (Lipandra polysperma, syn. Chenopodium polyspermum)
Source: en.wiktionary.org