A Dark Riddle

I found it in the deep,
in the dwellings down below,
not on the mountains steep
where the grim gusts blow.

I found it in the cold
in the downy drifts of snow,
and in the woods of old
where the pail pods grow.

It never has its heart
where the sunshine has its sway,
but ever at the start
of a dull, dark day.

I saw it not in blooms
nor in floating, falling leaves.
It will not stay in rooms
'neath the shelt'ring eaves.

You'll find it in the red
of the blood shed by a friend,
and in your final bed -
always at the end.

And though in death it's found
it pervades the puzzled head.
In riddles was it ground
and in dark doubt bred.