Document ID: chunk:federal_register_of_legislation:F2023L01376:reg:2:p1
Version: federal_register_of_legislation:F2023L01376
Segment Type: reg
Provision Reference: reg 2 (pt 1/8)
Character Range: 18581–21799

2               Biological information

Introduction
Macadamia belongs to the Proteaceae, an ancient angiosperm family whose initial differentiation from ancestral forms occurred in the south-east of Australia 90–100 million years ago. The family is well known for other genera such as Banksia, Grevillea and Hakea. Proteaceae appear to have been a major component of the early angiosperm dominated rainforests which once covered most of Australia. Macadamia were probably widely distributed within these early forests as evidenced by Macadamia type fossil pollen recorded in sediments in south-east Australia, central coastal Queensland and New Zealand.
The commencement of significant and permanent change in climate beginning about 40 million years ago resulted in a long-term trend of contraction of rainforest towards coastal areas, which accelerated through the Quaternary period. This process contributed to adaptation to drier fire prone habitats by much of the Proteaceae family, with a relict rainforest component including Macadamia, becoming progressively more restricted and disjunct in distribution over time and space.
Macadamia are endemic to the north east NSW and south east Queensland coastal regions. They are mid stratum or sub canopy trees whose prime habitat is subtropical rainforests, although they are also found in sclerophyll forests where rainforest is subdominant (often its presence is fire mediated).
Macadamia flowers are racemes of cream or pink flowers, which are followed by hard, woody fruits that enclose a hard-shelled nut containing a cream kernel. In two of the four Macadamia species, this kernel is edible, and cultivars of these species are the grown extensively within Australia and overseas. Macadamia flowering appears to be light-limited; trees growing within rainforest environments produce far less flowers than backyard or orchard trees, though, trees on rainforest edges or in forest gaps may produce abundant flowers.
The four species of Macadamias are all genetically closely related and three – M. integrifolia, M. ternifolia and M. tetraphylla – have overlapping ranges (refer Figure 1); M. jansenii is the exception and is known only from a single location 150 km north of the closest Macadamia population. The natural distribution of M. integrifolia, M. ternifolia and M. tetraphylla are predominantly restricted to a narrow east-west zone encompassing the coastal ranges and foothills west of the Pacific Ocean. Table 2 summarises the characteristic features that help to distinguish Macadamia species from each other.
Table 2. Distinguishing features of Macadamia species
Species                 Feature                                                                           
                       Leaves                                                              Flower colour  Nuts
Macadamia integrifolia  3 leaves per node; smooth edges to older leaves; green new flush    Cream          Thick, hard, smooth shell; edible kernel
Macadamia jansenii      3 leaves per node; smooth edges to leaves; green or pink new flush  Cream          Small with thin, smooth shell; bitter kernel
Macadamia ternifolia    3 leaves per node; spiny leaves; pink new