Attachment of branches in Schefflera is unusual in that it involves fingerlike woody extensions that originate in the cortex and pass gradually into the woody cylinder of the parent shoot. We tested the hypothesis that these structures could be roots since Schefflera is a hemi-epiphyte with aerial roots. These branch traces originate by secondary development in the many leaf traces (LTs) of the multilacunar node together with associated accessory traces. In the primary condition, the LTs may be described as cortical bundles. Leaves are long persistent and can maintain a primary stem connection across a broad cylinder of secondary xylem. Under the stimulus of branch development, the LTs form a template for secondary vascular development. Because the LT system is broad, with many traces, the branch attachment is also broad. The fingerlike extensions are attached to the surface of the woody cylinder of the parent stem but are progressively obscured as a continuous cambium is formed. Bark tissues are included within the branch axil because of the extended cortical origin of the initial attachment. The results are discussed in the context of branch-trunk unions in tropical plants, an important component of canopy development.
In this article, we propose that an organism's general architecture is of primary importance for its ability to perceive electromagnetic radiation. Animals develop mainly as volumes for internal assimilation and appendages to increase their mobility, while plants develop as surfaces to optimize interaction with the environment. As a consequence, the proportion of cells directly interacting with EMF radiation at the organism/environment interface is much higher in plants than it is in animals, making them especially suited to study EMF effects on life.
Modular growth in seed plants may be analysed in terms of three architectural elements: the unit of morphogenesis, the module and the architectural model. Some of the salient features of these structures are reviewed, compared and contrasted. A variety of plant shapes and sizes may be derived schematically from them by two sorts of transformation, gigantism and repetition. The former is uncommon in seed plants, but repetition produces a wide array of constructions. Repetition of the architectural model, a process known as reiteration, leads to a colonial structure characteristic of the crowns of many mature trees. This is often an expression of the plant’s opportunistic response to environmental variations in resource availability. The reiterated complexes formed as a result may show some characteristic ontogenetic and phylogenetic sequences to give an architectural continuum of construction.
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