Download the rule for Arboretum or any other documents (scenarios, goodies, pedagogical sheet, erratum, ...). 2 PDF files are available.
pdf https://cdn.1j1ju.com/medias/28/63/eb-arboretum-rulebook.pdf
Exception: If a player has the 8 of a color in her hand, but one of her opponents has the 1 of the same color in his hand, the value of the 8 is reduced to 0 when determining which player has the right to score paths of a particular color. The 1 is always worth 1. (See scoring example.)
1.02 Mo - In Englishpdf https://cdn.1j1ju.com/medias/ca/63/46-arboretum-regle.pdf
Exception : si un joueur possède le 8 dans sa main et qu’un autre joueur possède le 1 de la même couleur, la valeur du 8 est réduite à 0 pour déterminer le joueur qui pourra marquer les points d’un sentier. Le 1 vaut toujours 1.
1.12 Mo - In French