No matter how many times I read them, I always find something new in these less-than-2 pages. The mood is set perfectly, even down to the heavy oak and iron spikes of the prison door. The adjectives say it all: ponderous, gloomy, sad, grey. The vegetation he lists? All either are poisonous or will give you many and nasty pricks.
But near the threshold of that "black flower of civilized society" and in contrast to the weeds is a "wild-rose bush" beautiful both to see and smell. A gift of hope from nature: The last of the outside world a prisoner sees as he goes in, and the first thing to greet a prisoner when he or she leaves the prison.
Themes and motifs are introduced here; these few words hold the seeds that will bloom during the story. (Too sappy? :-))