Fig. 4

Comparative morphology and bract anatomy of E. breana seed cones. A Seed cone in Stage 1, with green bracts (br). Black arrows indicate the fused region of the distal bracts. B Seed cone at Stage 3, with fleshy red bracts. Black arrows indicate the fused region of the distal bracts. Note the highly developed distal bracts that completely enclose the seeds, which are not visible as in the other species studied. C Overview of anatomical section in the region of seed cone bract fusion (black arrows). D Cross section of seed cone bract at Stage 1 stained with toluidine blue O and PAS showing large tannin content in cells of the adaxial epidermis. Cellulose fibers (f) are grouped into layers on the adaxial side. A vascular bundle is surrounded by transfusion tissue (t), phloem (p) and xylem (x). Mucilaginous parenchyma is evident abaxially, and the abaxial epidermis is composed of cells with tannins and stomata. E Polarized light microscopy of section in D showing the birefringence of cellulosic fibers (f) and xylem. F Cross section of the seed cone bract at Stage 3 stained with toluidine blue and PAS showing increased of cell size and loss of carbohydrates from the cytoplasm of mucilaginous parenchyma cells. Fiber layers (arrows) are reduced in number and grouped in bundles beneath the adaxial epidermis. G Polarized light microscopy of the section in F showing the birefringence of cellulosic fibers (white arrows) and xylem. Scale bars: 1 mm (A, B); 200 µm (C); 100 µm (D–G)