Alder is what Leo Fender used on his first bolt on guitars and so did PRS before he decided to go mass production. Alder is a great tone wood and it costs very little. Some of the drawbacks are it is harder to work with than say poplar or basswood.

Many companies who used Alder have switched to Poplar or Basswood for economic reasons.  Basswood is not a favored tonewood but Poplar sounds quite good. Poplar requires a lot of filler and I don't recommend it unless you can find it in a good quality.  (Rare)

The only company that I ever saw use Poplar effectively was Parker on their very first models.

Poplar doesn't sound good on all guitars and neither does Alder. They work well with bolt on type guitars that utilize hard maple necks.

Call if you want to discuss the properties and tonalities of these woods.

Black Alder (Alnus Glutinosa).

Alder is a fast growing deciduous tree adapted to swampy areas and self sufficient in nitrogen uptake. It’s distribution area is Europe, Russia and north-west of Africa. In Sweden it’s distributed up to the middle part and along the Norrland coast. There is one more alder species, Grey alder (Alnus Incana), with it’s major distribution in northern Sweden. Grey Alder has similar wood properties as Black Alder but is somewhat softer.

Alder wood

Alder is a light, relatively soft and medium tough wood among the wood species. It’s relatively form stable during moisture variations. The Alders color and structure of the wood, softness and reluctance to shrinkage and swelling makes it suitable building guitars.

Alder wood and its appearance

The Alder has a light red color. Small clusters of minor knots is common in the wood. Brown traces from harmless kambium insects can occur and also brown heart, fresh knots and black rotten knots.

Alder wood and its technical properties

Alder wood and its technical data