Have you ever noticed a clump of grass or some other plant stuck to the top of a street sign post. I have. Quite a few times, actually. Usually it’s just a clump of grass, but sometimes (as here) it’s some other type of plant (holly?).
I used to think it was just a twig that somebody stuck in the top of the pole, but then I took a closer look. There’s actually a skinny fucking plant growing right up the middle of the pole! There’s another one growing near our house: same deal! (Click for full-size.)
Presumably, the plant is protected inside the pole and gets plenty of light and air through the holes while it’s growing:
Then, when it get’s big enough, it starts growing out the top! Amazing!