Images showing the attachment of root-bearing axes shown in blue to leafy shoots shown in green based on our 3D reconstruction (A, D–F) and the thick sections used to create the reconstruction (B, C, G–I). (A) A root-bearing axis shown in blue attached to the side of the larger plagiotropic leafy shoot axis shown in green. (B) The thick section represented by arrow one in (A) showing a transverse section through the leafy shoot at the point of branching. The black xylem trace of the rooting axis is located to the left of the cross shaped xylem at the centre of the leafy shoot axis. (C) Thick section represented by arrow two in (A) showing the free root-bearing axis with small rounded xylem trace compared to the larger cross shaped xylem in the leafy shoot. (D-F) Examples based on the reconstruction of A. mackiei of root-bearing axes attached to first order leafy shoots close to their attachment with the main leafy shoot. In each case, the root-bearing axes are smaller in diameter than the leafy shoots they are attached to and all root-bearing axes are aligned with the gravity vector. (G-I) Examples of thick sections showing the anisotomous branch point with attachment of a root-bearing axis and leafy shoot, the position of each thick section is illustrated on the reconstruction in (D), with arrow 1 (G), 2 (H), and 3 (I). (J) A bifurcating root-bearing axis with two apices attached to a larger leafy axis (leaves on large axis highlighted with arrowheads). (K) Higher magnification image of (J), showing the continuous cuticle covering the two apices and small leaf attached to the lower flank of the upper apex. 3D scale bar 1 × 0.1 × 0.1 cm (D–F), 2 × 1 × 1 mm (A). Scale bars, 5 mm (G–I), 2 mm (B, C) 1 mm (J), 500 µm (K). Specimen accession codes: Pb 4178 (B), Pb 4177 (C), Pb 4164 (G), Pb 4163 (H), Pb 4162 (I), Pb 2020_02 (J, K).