Bro, not only are they sentient, the trees fucking hate us. Allergies aren't just something that happens as a quirk of evolution. Those trees are filling the air with their jizz in a coordinated effort to take us out bro. The trees are trying to kill us bro.
There's a theory that allergies are getting worse due to an imbalance of gender selection when planting trees in urban environments. Here is some additional context.