Ragweed bloom spikes

Another kind of season is about to begin, and for many unfortunates, this will be the worst of times. I speak, of course, about allergy season—hayfever, a.k.a., allergic rhinitis, in particular—that is the result of the body's over-exuberent response to certain kinds of pollen in the air. In the spring, public enemy number one is tree pollen, which causes the itchy eyes, nasal congestion, and difficulties in breathing that are the hallmarks of this condition. In summer, the main cause of hayfever is pollen shed by grasses and, perhaps the worst offender of all, ragweed. In the past, many folks pinned the blame on the various species of goldenrod, but it turns out that they were taking a bum rap. Here's the source of your seasonal misery. which various species of Ambrosia—ironic name for a decidedly non-ambrosial condition—are getting ready to spread.