bitterweed has definitions from the field of botany
1
[ noun ] (botany) widespread European weed with spiny tongue-shaped leaves and yellow flowers; naturalized in United States

Related terms

weed Picris

2
[ noun ] (botany) any of numerous chiefly North American weedy plants constituting the genus Ambrosia that produce highly allergenic pollen responsible for much hay fever and asthma

Synonyms

ambrosia ragweed

*