|"Is this all real? Or has this been happening inside my head?"
The topic of this article is of a real-life subject that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really existed), and, as such, details contained in this article may differ from real world facts.
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 called spruce a difficult wood, but in doing so they revealed their own ineptitude; it was quite true that it required particular deftness to work with spruce, which produced wands that were ill-matched with cautious or nervous natures, becoming positively dangerous in fumbling fingers.
The spruce wand required a firm hand, because it often appeared to have its own ideas about what magic it ought to be called upon to produce. However, when a spruce wand met its match - which, in Garrick Ollivander's experience, was a bold spell-caster with a good sense of humour - it became 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 medieval Polish-speaking merchants would import the timber to England and the English would pick up the expression from them.