The species collected in the Pantanal and prepared according to the usual techniques for anatomical studies showed similar structural characteristics, and data on the arrangement of vascular bundles in the midrib and petiole, as well as the form and distribution of sclereids, were consistent.
According to Wiersema (1987), this subgenus is characterised by completely fused carpels, a swollen carpel appendage, and a usually tetramerous arrangement of perianth and outer stames, with or without acicular sclereids.
Some quantitative characters were not taken into account because they increase with age; these include: adaxial and abaxial prominency of the main rib, number of layers of parenchyma cells, of fibrous strands under the adaxial and above the abaxial hypodermis, of layers of sclereids, of chlorenchyma and spongious parenchyma.
Nine differential characters: epidermal cells rectangular (95), oval (96), round in outline (97), with outer wall thick or thin (98, 99); hypodermis with parenchyma (100), sclereids (101) or septate fibers (102); fibrous strands with stegmata (103).
Sclerenchyma generally falls into two categories of cells: fibers and sclereids, or stone cells.
Sclereids are variable in shape, some being highly branched like an octopus, others shaped like a bone, and still others relatively spherical.
At the boundary between the peridermis and the secondary phloem there was a continuous ring of sclereids