I don't know a precise definition, but wood has many origins. Wood has evolved hundreds of separate times, including at least 38 separate times just on the Can

I don't know a precise definition, but wood has many origins. Wood has evolved hundreds of separate times, including at least 38 separate times just on the Canary Islands. https://www.researchgate.net/publication/341287935_Multiple_origins_of_insular_woodiness_on_the_Canary_Islands_are_consistent_with_palaeoclimatic_aridification https://www.researchgate.net/publication/341287935_Multiple_..., https://www.pnas.org/doi/pdf/10.1073/pnas.2208629119?download=true https://www.pnas.org/doi/pdf/10.1073/pnas.2208629119?downloa...