Born in Pictou, NS, Dawson studied natural history at Edinburgh and became principal of ɬÀï·¬ in 1855. His main interest was paleobotany, keeping many of his type fossil specimens at ɬÀï·¬'s Redpath Museum, but he also collected plants that are now stored at ɬÀï·¬'s herbarium.
Dawson taught botany from 1858 until 1882 and was largely responsible for the foudning of a separate botany department in 1844. He was a naturalist in the old tradition and, above all, an educator.