Full text
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| Author(s): |
Karen Lucia Mayumi Sasaki
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2015-05-04 |
| Examining board members: |
Nanuza Luiza de Menezes;
Graziela Cury;
Diego Demarco
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| Advisor: | Nanuza Luiza de Menezes |
| Abstract | |
Plants of the genus Cordyline possess distinctive caulinar structures usually known as rhizomes. An author from the early twentieth century suggested that there was a relationship between this organ in Cordyline and the root-generating organ in Selaginella. The term rhizophore - meaning \"root-bearing organ\" - was coined originally for Selaginella and was later applied to the subterranean stem organs of Vernonia, Dioscorea and Smilax and to the structures traditionally known as aerial roots in Rhizophora mangle. Recently, these structures in Cordyline fruticosa have been categorized as rhizophores, but this hypothesis has not previously been confirmed by any published developmental study. A rhizophore is a stem with positive geotropism which does not arise from the plumule of the embryo, and is present in plants with a stem system having bipolar branching, i.e. with aerial branches, which have negative geotropism and form leaves, and basal branches, which have positive geotropism and form roots. The rhizophores of Cordyline develop from lateral buds and have secondary growth of the same type as in the aerial axis. The stem thickening of Cordyline has already been extensively studied in its aerial parts, but there are few such studies regarding the subterranean part of the stem. This thickening is the direct and indirect result of the activity of the pericycle. In the primary body, the pericycle produces additional vascular tissue, which increases the diameter of the stem concomitant with the meristematic activity of the endodermis. The pericycle is also responsible for the generation of the STM, which provides the secondary thickening and functions in a similar way in the aerial stem and the rhizophore, with little variation. The adventitious roots vascular tissue are connected to the vascular system of the stem by the pericycle during primary growth and by the STM during secondary growth. The morphological and anatomical features of the rhizophore are directly related to an increased production of roots, and thus its main function is the rhizosphere expansion. Beside that, the rhizophore is important as a storage organ and vegetative reproduction. The present study investigated the structure of the subterranean organs of Cordyline fruticosa, C. australis and C. spectabilis by anatomical techniques and observations of their ontogenetic development. (AU) | |
| FAPESP's process: | 11/15669-8 - Morpho-anatomical studies in vegetative organs of Cordyline fruticosa (L.) Chevalier, C. australis (G. Forst.) Endl. and C. spectabilis Kunth & Bouché. |
| Grantee: | Karen Lucia Mayumi Sasaki |
| Support Opportunities: | Scholarships in Brazil - Master |