Birdseye
Birdseye
Birdseye
So far no-one has come up with a proven reason for the phenomenon called Birdseye. The normal grain pattern is interrupted by small little "eyes" that look like tiny knots. The frequency of these "eyes" has a direct correlation to the value of wood with Birdseye. The more "eyes" the more value. Probably the most renown wood for Birdseye is Maple.
Burr
Birdseye
Birdseye
This is when the wood grain is actually deformed, making it very difficult to work, but in the hands of an experienced craftsman it is a true blessing. Burr wood is very highly prized by those with the ability to work it, mainly due to the beauty of the misshaped grain. Burr wood is uncommon and usually very expensive. In my experience a lot of burls have this type of grain.
Burl
Birdseye
Curly
A burl is an outgrowth on a tree. As it is the product of a cambium of the tree and is the product caused by a myriad of dormant buds that appear as little knots. Burl grain isn't a burl grain without these little dormant buds. All species of tree will produce burls, but they are more common in some species than others. Burls have a very peculiar and highly figured grain pattern, making them highly prized and expensive.
Curly
Crotch
Curly
Curly wood grain is a term I'm not real sure why we use anymore as there are so many variances to Curly grain. Tiger grain, Fiddleback grain and Quilted grain are some examples.
Crotch
Crotch
Crotch
This is where a section of the tree has divided due to the outgrowth of a branch, or it may be simply where the trunk divides in two. Usually, this will produce a very beautiful integrated grain pattern that may even produce an iridescent (some call it a Tiger-eye) appearance. Occasionally, a grain pattern called feather crotch will be present, which further increases the value of the wood and any product made from it.
Flamed
Crotch
Crotch
Flamed or flaming in wood grain is the abnormality that appears as flames. Sometimes, in some species, there will be an unusual color inclusion along with the flame appearance. The red in this Flamed Box Elder is the "Flamed" grain.
Spalted
Spalted
Spalted
Spalted or Spalting is actually zone lines in the wood that are caused by an antagonistic wood rotting fungus. The cause of the fungal intrusion is varied, but the result is very unusual and often beautiful patterns of black lines are created. Spalted wood can be very deceptive as to it's quality of useable wood due to this fungal growth; I've had some spalted wood with a very slight amount of spalting that was totally punky and other pieces that had extreme spalting that were completely solid.
Tiger
Spalted
Spalted
Tiger is almost always considered to be a grain that appears in Maple. Often referred to as curly or flamed, they all basically mean the same thing. The difference is the way these "rays" appear in correlation to the rest of the grain.
Quilted
Spalted
Ambrosia
Quilting is not restricted to Maple, although it seems to be more common in Maple than others species of wood. Quilted refers to the quilted appearance of the wood grain, often appearing like water ripples.
Ambrosia
Trunk Burl
Ambrosia
Ambrosia is another wood grain type that is usually associated mainly with Maple.
Trunk Burl
Trunk Burl
Trunk Burl
The picture above shows a trunk burl and I think you can see the evidence that there is probably a root burl underground. If you are harvesting burls; great care must be given to the drying process as very often they will split and crack, often breaking your heart at the loss of one of these beauties. These growths can be anywhere on the tree, but from what I've seen the root burl still is the supreme grain.
Fiddleback
Trunk Burl
Trunk Burl
Fiddleback is one grain type I'm including so you at least know what it can look like. (Still looks like an extreme version of Curly to me.)