"In a Station of the Metro" analysis

The title of this short poem tells you the setting and from some of the wording (black, wet, crowd) it seems as though she is trying to portray the metro as a not entirely pleasant place. The line"Petals on a wet, black bough." is probably talking again about the people who have 'these faces' in the crowd and how they are just a part of something bigger or in a bigger place like the Metro Station, yet for some reason she feels the need to mention them as though they stuck out and were different for some reason.