"IAWA List of Microscopic Bark Features" published on 22 Nov 2016 by Brill.

A new method is presented to prepare anatomical slides of plant materials including a combination of soft and hard tissues, such as stems with cambial variants, arboreal monocotyledons, and tree bark. The method integrates previous techniques aimed at softening the samples and making them thereby more homogeneous, with the use of anti-tearing polystyrene foam solution. In addition, we suggest two other alternatives to protect the sections from tearing: adhesive tape and/or Mayer’s albumin adhesive, both combined with the polystyrene foam solution. This solution is cheap and easy to make by dissolving any packaging polystyrene in butyl acetate. It is applied before each section is cut on a sliding microtome and ensures that all the tissues in the section will hold together. This novel microtechnical procedure will facilitate the study of heterogeneous plant portions, as shown in some illustrated examples.

Background: Lianas present many interesting structural features that are linked to their climbing habit. Having lost substantial amounts of supporting tissue, these plants depend on external structures for support. Meanwhile, during their evolutionary history, they have gained additional conductive and storage tissues. The wood of lianas generally includes wider vessels, larger amounts of axial parenchyma, larger rays, and longer fibres than those of trees. Cambial variants represent another key anatomical feature of lianas. Aims: In this paper, we review various aspects of liana biology, including those associated with their vascular system and water conduction, secondary growth and seasonal responses to environmental variability, as well as aspects related to the evolution of their cambial variants. Methods: Examples from the Bignoniaceae and Leguminosae, the two most abundant liana taxa in the Neotropics, are presented in a series of case studies, bringing new data, such as the activity of the cambium during the dry seasons; the radial conducting elements that are associated with the habit; the cambial variant of Bignonieae that has evolved in a recapitulatory fashion; and the increased specialisation for photosynthate conduction by the phloem. Conclusions: Altogether, lianas represent an excellent model for studies on the convergent evolution of plants.

Cambial activity and periodicity of secondary xylem formation in Cedrela fissilis, a semi-ring-porous species, were studied. Wood samples were collected periodically from 1996 to 2000. The phenology was related to climate data of the region. The cambium has one active and one dormant period per year. The active period coincides with the wet season when trees leaf-out. The dormant period coincides with the dry season when trees lose their leaves. Growth rings are marked by parenchyma bands that begin to be formed, together with the small latewood vessels, just before the cambium becomes dormant at the beginning of the dry season. These bands are added to when the cambium reactivates in the wet season. At this time, the large earlywood vessels of the growth rings are also formed. As these bands consist of both terminal and initial parenchyma, we suggest the general term marginal bands be used to describe them. The growth layers vary in width among and within the trees.