Spruce (genus Picea) is a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the earth.
Unskilled wandmakers call spruce a difficult wood, but in doing so they reveal their own ineptitude; it is quite true that it requires particular deftness to work with spruce, which produces wands that are ill-matched with cautious or nervous natures, becoming positively dangerous in fumbling fingers.
The spruce wand requires a firm hand, because it often appears to have its own ideas about what magic it ought to be called upon to produce. However, when a spruce wand meets its match - which, in my experience, is a bold spell-caster with a good sense of humour - it becomes a superb helper, intensely loyal to their owners and capable of producing particularly flamboyant and dramatic effects.
The word "spruce" entered the English language from Old French pruce, the name of Prussia. Spruce was a generic term for commodities brought to England by Hanseatic merchants and the tree was believed to have come from Prussia. According to a different theory, some suggest that it may however be a direct loanword from a Polish expression drzewo/drewno z Prus which literally means "tree/timber from Prussia". That would suggest that the late mediaeval Polish-speaking merchants would import the timber to England and the English would pick up the expression from them.