Morphological and Anatomical Variations of Roots, Leaves, Peduncles, and Peduncle Bracts in the Vriesea oligantha Complex (Bromeliaceae): Perspectives for Taxonomy

Abstract

Abstract—Vriesea is one of the genera of Bromeliaceae with the highest morphological diversity, including species of difficult recognition, many of them forming complexes, such as the Vriesea oligantha alliance. Morphological and anatomical comparative studies of vegetative and reproductive organs proved to be useful to solve such species complexes, besides indicating adaptive radiation. We analyzed comparatively the anatomy of roots, leaves, peduncles, and peduncle bracts of different populations found in rocky fields of Minas Gerais and Bahia, Brazil, with a taxonomic goal. In all the individuals studied the roots are composed of a velamen, a heterogeneous cortex, and a polyarch vascular cylinder, features that are common in the family. The leaves are covered by peltate trichomes and exhibit a hypodermis on both sides of the blade and a chlorenchyma composed of arm cells forming air lacunae between the collateral vascular bundles. The presence of subepidermal fiber strands in the leaves differentiates the populations of Minas Gerais from those of Bahia. The peduncle has an atactostele with compactly arranged cells in the cortex and pith. The peduncle bracts exhibit a greater number of peltate trichomes on the abaxial surface and secretory channels occur in the mesophyll. A cluster analysis (UPGMA) based on leaf morphology and tank channel diameter generated a dendrogram with four main clusters, which correspond to V. lancifolia, V. oligantha, and V. pseudoligantha, plus another taxon. Intraspecific variations in the color and margin shape of leaves and peduncle bracts are interpreted as adaptive responses to environmental factors, mainly luminosity.

Ontogenetic changes in root traits and root‐associated fungal community composition in a heteroblastic epiphytic bromeliad

“…In spite of that, we showed a progressive increase in the size of the root meristem during ontogeny with increased radial area of each tissue along ontogeny. Although larger velamen in the tank stage is subject to greater construction costs (Enquist et al 1999), it generally confers higher ability to absorb water and nutrients, and higher resistance to water loss and mechanical damage (Zotz and Hietz 2001, Pita and Menezes 2002, Segecin and Scatena 2004, Proença and das Graças Sajo 2008, Silva et al 2020). Thus, the velamen is presumably an important regulator to enhance the adaptability of L. splendens to the epiphytic environment.…”

“…Graças Sajo 2008, Silva et al 2020). Thus, the velamen is presumably an important regulator to enhance the adaptability of L. splendens to the epiphytic environment.…”

Hohenbergia erecta (Bromeliaceae: Bromelioideae), a New Once-branched Species from Chapada Diamantina, Bahia State, Brazil

“…Our collection expeditions through the State of Bahia have been carried out over the past three years and the morphological studies have been performed based on living materials under natural conditions as well as studying images of herbarium specimens available on-line. Specimens of the new species were taken to a greenhouse for cultivation and observation of possible structural variations in plant architecture (Silva et al, 2018(Silva et al, , 2020…”

Underlying microevolutionary processes parallel macroevolutionary patterns in ancient neotropical mountains

“…All share similar vegetative and reproductive traits, such as green-greyish leaves, plumose wind-dispersed seeds and nocturnal yellow flowers, which are usually associated with pollination by moths and bats. Such similarities yielded poor taxonomic delimitation over time (Machado et al, 2020;Philcox, 1992), although recent morfo-anatomical traits were in agreement with these taxa (Silva et al, 2020). For the purpose of this work, we considered all sampled individuals as belonging to the V. oligantha species complex.…”

“…Such climatic variation has the potential to rapidly influence evolution by triggering ecological divergence (Campbell & Powers, 2015), especially in a scenario with reduced interpopulation gene flow as observed in V. oligantha (Figure 3 and Figure S4.4). In fact, the four phylogeographic lineages (Figure 2) present some anatomical and morphological differences (Silva et al, 2020) that might be associated with adaptive responses to environmental factors.…”