Witch's Brooms

 
Here is a Pinus sylvestris (Scots pine) that has sported a broom.  Notice the obvious difference with shortened internodes and needles; even the color is different.  The broom stands out from the longer, more openly spaced needles of the tree.
A close up of the broom demonstrating the very compact nature of this mutation.
Here you can see the cultivar created by propagating from the broom

 

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