|"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.
Cypress is the name applied to many of the plants belonging to the cypress family, Cupressaceae, which is a conifer. Most cypress species are trees, while a few are shrubs.
Garrick Ollivander noted that cypress wands were associated with nobility. The great medieval wandmaker, Geraint Ollivander, wrote that he was always honoured to match a cypress wand, for he knew he was meeting a witch or wizard who would die a heroic death.
Fortunately, in these less blood-thirsty times, the possessors of cypress wands were rarely called upon to lay down their lives, though doubtless many of them would do so if required. Wands of cypress found their soul mates among the brave, the bold and the self-sacrificing: those who were unafraid to confront the shadows in their own and others' natures.