Alder Comes in three major categories, which are European Alder, Nepalese Alder, and Red Alder Hardwood. They all share some qualities, for instance the lack of visible differences between sapwood and heartwood.
European Alder Hardwood (Alnus Glutinosa)
Also referred to as Black Alder or Common Alder, this wood has a reddish hue that begins as a lighter tan and becomes a darker red as the wood gets older. The grain is even, but the pores are very closed which can make it somewhat harder to paint. Different trees with have different grain patterns, with some being straighter while others are more varied. The wood lacks the endurance seen by some others, and must be immediately treated upon cutting. Natural staining and decaying are both concerns unless the wood is properly dried and treated with due haste. The upside to its lack of durability is that the wood is easily workable. While technically considered a hardwood, its relative softness lends to easier shaping and sanding.
Nepalese Alder Hardwood (Alnus Nepalensis)
This wood hailing from Southeast Asia comes from relatively sizable trees which grow up to one hundred feet in stature and measure a whole meter in diameter. The coloring on Nepalese Alder is similar to that of the European Alder, and also shares the quality of growing darker over time. Its grain is even more predictable than that of European Alder, tending to run consistently straight and even with tight pores. This is another wood which is softer than most hardwoods and is therefore easily sanded. Shaping is not too difficult with either hands or machines.
Red Alder (Alnus Rubra)
Springing up throughout the western coasts of North America, Red Alder trees average between 100 and 130 feet in height with generally a meter of diameter. Like European and Nepalese Alder woods, this wood runs from a tannish color to a ruddier brown, and the hue of the wood tends to become both redder and darker as the wood grows older. The pores on Red Alder are not very large, and the grain is consistently straight and fine.