Bamboo is a natural composite and one of the most efficient structures in nature because of the relationship of mechanical properties with its microstructural features. This research presents the 3D characterization of the reinforcement bundles of a branching nodal region of bamboo, through high-resolution X-ray microtomography (µCT). µCT was used to characterize a sample regarding the volume, relative density, and porosity of parenchyma and sclerenchyma tissues, and the resulting data were used to estimate their constitutive properties. A nonlinear finite element analysis (FEA) was performed based on a discretized model of the µCT to the limiting compressive load. Secondary bundles presented an interweaved arrangement into the primary vascular elements that distribute axial compressive stresses into new branches. Our findings suggest that the foam-like behavior of the parenchyma, the sclerenchyma thickening above the nodal zone, and the nodal vascular branching are ways for bamboo to protect important tissues from mechanical stress by allocating axial loads. In addition, such mechanism could be applied in the design of biomimetic structures with selective load-bearing capabilities.

In Nidularium, inflorescence branches are subtended by large floral bracts, in which water accumulates. The branching pattern is obscured because their internodes remain short, hampering their interpretation. This study focuses on the development of the inflorescence in N. innocentii, combining different approaches in order to understand its architecture and summarize it in a three-dimensional (3D) model. We also present the interpretation of tank-inflorescence development, recognizing the processes that have taken place in the evolution of this structure in this group. The inflorescence was typified based on Troll’s and Weberling’s systems. Development was studied using light microscopy and X-ray microcomputed tomography. The system is polytelic; the main axis ends in the main florescence and bears lateral paraclades with coflorescences. Each lateral branch develops in the axil of a bract, which is large and displays alternate arrangement. No prophylls were observed in the system. In the 3D reconstruction, the volume of the model was calculated. The volume of the empty region is c. 2.4 times higher than the plant material. Tank-inflorescence development seems to have occurred by the combination of three processes: bract disposition and its overgrowth; failure in internode elongation; and paraclade flattening. The tank-inflorescence evolved in a few groups of core bromelioids, and may be associated with floral protection.

Tillandsioideae are composed of nine genera, most of these with unclear delimitation. The morphoanatomy of ovules and ovaries of 83 species from seven

The genus Rhynchospora Vahl. (Cyperaceae) has about 270 species, two subgenera and 27 sections. Cytogenetic studies showed that polyploidy is the main mechanism of numeric changes in the karyotypes of Rhynchospora. However, some species have exhibited some evidence of agmatoploidy and symploidy. The occurrence of holocentric chromosomes seems to support more the events of fusion (symploidy) and fission (agmatoploidy), leading to the appearance and maintenance of intra- and interspecific variations based in disploidy. In this study, chromosome counts and recounts were performed in 14 species obtained from different Brazilian localities. New chromosome numbers have been reported for R. tenuis, R. globosa, R. pubera, R. nervosa, R. junciformis and R. asperula. The analysis showed the absence of primary constrictions on the chromosomes and numeric variation from 2n = 4 to 2n = 58. The primary (x = 5) and secondary (x = 6 and 9) basic numbers were again confirmed. Our results expand the information related to chromosome rearrangements in Rhynchospora and reinforce the role of polyploidy and dysploidy in karyotype differentiation in representatives of Cyperaceae.