common ragweed: annual weed with finely divided foliage and spikes of green flowers; common in North America; introduced elsewhere accidentally
ragweed: any of numerous chiefly North American weedy plants constituting the genus Ambrosia that produce highly allergenic pollen responsible for much hay fever and asthma
palladium: a silver-white metallic element of the platinum group that resembles platinum; occurs in some copper and nickel ores; does not tarnish at ordinary temperatures and is used (alloyed with gold) in jewelry