Pollen
From Memory Alpha, the free Star Trek reference
Pollen is a powder consisting of microgametophytes (pollen grains), which produce the male gametes (sperm cells) of seed plants.
Toxic pollen produced by psychotropic flowers on the planet Archer IV, the first planet visited by the Enterprise NX-01, contained tropolisine and caused paranoia and hallucinations in humanoids. (ENT: "Strange New World")
Malcolm Reed was allergic to oak pollen, as well as bromelain, dust mites and tropical grasses. (ENT: "Silent Enemy")
Bees, Earth insects that make the key ingredient in beeswax candles, gather pollen from flowers. (TNG: "A Fistful of Datas")
