Alder I never used if Im no mistaken is that is a flowering shrub related to the birch family. It rarely gets to extensive sizes or heights. Im a firm believer that a lot of paleo groups used various species including shrubs and bushes. I think that plants like that have intermingled grain making for great compression but who knows I have made bows from huckleberry bush, Mt. Laurel, and sumac. Would u know they work. Take care.
Russ