Wood anatomy of Brabejum and Macadamia (Macadamiinae, Proteaceae)

Wood structure of Brabejum stellatifolium and Macadamia integrifolia (subtribe Macadamiinae, tribe Macadamieae, Proteaceae) is described for the first time. These species share exclusively simple perforation plates, minute to small alternate intervessel pits, non-septate libriform fibers, banded and unilaterally paratracheal axial parenchyma, and the rays of two distinct sizes, i.e. the suite of typical wood traits for many of Proteaceae. Our observations together with reported data suggest that the lineage comprising Brabejum, Macadamia and Panopsis is distinctive from closely related members of the tribe Macadamieae by the occurrence of vasicentric tracheids combined with the lack of fiber tracheids. More abundant axial parenchyma in Macadamia and Panopsis than in Brabejum is seemingly consistent with the global tendency to increase of amount of this tissue in the regions with warm climate. Libriform fibers is Macadamia integrifolia show one of the highest degrees of intrusiveness (F/V ratio = 3.98) reported within Proteaceae to date.