There are many imperfections found in the English Willow Tree that go on to still be present in the finished bat.  Here we give an overview of the most common to reassure the consumer that they are only cosmetic.

Probably the most common imperfection found is the small knot or "pin knot".  These are generally up to 10 mm in diameter and are still living.  Normally they will be present in the edge and / or back of the bat although sometimes they are visible on the face.  They will not affect the playing of the bat at all.
"Speck" is another which is due entirely to the growing conditions of the tree.  The tree has grown in earth containing a lot of gravel and / or stones.  The tree has taken tiny molecules up into itself with water and this gets deposited along in between the grains.  It is purely cosmetic and is also the sign of a strong bat that will last.
This is "Butterfly Stain", so called as it resembles the body and wings of a butterfly.  It is actually attributed to the tree being of a hybrid of English Cricket Bat Willow, it is very strong and plays well.  It is just a matter if you like to have a bat that looks a bit special.
This is a more pronounced form of Butterfly Stain and is known as Bar Stain.  Again the wood is very strong and you can tell the difference from Butterfly Stain by the fact that this has many "Bars" of stain very close together.
A very common imperfection is the "False Growth".  This is caused when for some reason the tree has stopped growing for maybe one season.  It can be caused by drought, fire or weed killer.  Nine times out of ten there is no weakness in the bat and they will certianly not break along the False Growth.  It will normally run parallel to the normal grains.
This blade has a brown line down the middle as you can see in the photograph.  It has been caused by the roots having been cut either by a digger or perhaps a plough. It is rot in the very early stages but not to the detriment of the playing ability.
This is a "dead knot".  The tree has been trimmed up very late and the resulting branch has been left to grow for many years.  Before this can be used to make a bat the knot is drilled out and filled.  As long as it is not on the face of the bat it will have very little detrimental effect on the playability.