ragweed

n [U, C] N American weed producing large amounts of pollen which causes hay fever 豚草（产於北美, 其花粉能使人患枯草热）.

raffishly, raffishness, raffle, raft, rafter, raftered, rag, rag-and-bone man, rag-bag, ragamuffin, rage, ragged, raggedly, raggedness, raging, raglan, ragout, rags, ragtag, ragtime, ragwort, raid, raider, rail, railhead, railing, raillery, railroad, railway, railway-line, railwayman, raiment, rain, rain cats and dogs, rain forest, rain out, rain-check, rain-gauge, rain-swept, rain-water,