What is the line to line analysis of Sinner’s Rue by A. E. Houseman?

Sinner’s Rue
Houseman

I walked alone and thinking,
And faint the nightwind blew
And stirred on mounds at crossways
The flower of sinner’s rue.

Where the roads part they bury
Him that his own hand slays,
And so the weed of sorrow
Springs at the four cross ways.

By night I plucked it hueless,
When morning broke ‘twas blue:
Blue at my breast I fastened
The flower of sinner’s rue.

It seemed a herb of healing,
A balsam and a sign,
Flower of a heart whose trouble
Must have been worse than mine.

Dead clay that did me kindness,
I can do none to you,
But only wear for breastknot
The flower of sinner’s rue.