Question: Pseudotsuga, found in North America and Eastern Asia which has also been classified as 'Abies' and 'Tsuga' and Huernia which is found in Eastern and Southern Africa and closely related to 'Stapelia' and 'Hoodia' are both types of what?
Sentence (from "Pseudotsuga"): Nineteenth-century botanists had problems in classifying Douglas-firs, due to the species' similarity to various other conifers better known at the time; they have at times been classified in "Pinus", "Picea", "Abies", "Tsuga", and even "Sequoia".
Relevant evidence: Yes