A weed growing throught new tarmac

You're right @JennyJB, just like any plant that's planted too close to a neighbouring fence or wall and without any regular maintenance. Clumping bamboos usually grow no more than a couple of inches in diameter a year in the same way as a typical ornamental grass or perennial, unlike running bamboos that can send out horizontal runners of different lengths and in different directions.

 

I think little plants (aka weeds ) are quite common at the edge of tarmac. I certainly have them.