Morpho-Anatomical Analysis of the Rhizome in Species of Scleria Berg. (Cyperaceae) from Serra do Cipó (MG)

Abstract

Aspects related to the nature of stem thickening in monocotyledons have been the subject of many studies. Primary thickening has been attributed to the Primary Thickening Meristem (PTM). According to most authors, it gives rise, besides the adventitious roots, to the vascular tissues and part of the cortex. In other words, it has centripetal and centrifugal activity. For some authors, however, it gives rise only to the vascular system, and for others, only to part of the cortex. However, this work demonstrated that PTM corresponds to the pericycle in the meristematic phase or to the pericycle associated with the endodermis, also with meristematic activity. It was observed that the pericycle was responsible for the formation of the vascular system of the rhizome and of the adventitious roots; the endodermis gave rise to cell layers with radial disposition which comprised the inner portion of the stem cortex, and which corresponded to the region known as the derivatives of the meristematic endodermis (DME). A continuity was also demonstrated between the tissues of the stem and root in species of Scleria Berg. (Cyperaceae).

Developmental anatomy of Cyperus laxus (non-Nranz) and Fimbristylis dichotoma (Kranz) (Cyperaceae, Poales) and tissue continuity

“…The endodermal cells in the studied species present Casparian strips when meristematic activity ceased, and after the cell-walls became thickened, as was described in other species of monocotyledons (Menezes et al 2005, Leite et al 2009, Lima and Menezes 2009. Casparian strips in the endodermis cells of young rhizomes of Cyperus laxus and Fimbristylis dichotoma were also observed, as well Fimbristylis dichotoma were also observed, as well Fimbristylis dichotoma as, in other Cyperaceae and monocotyledons (Eiten 1969, Bendixen 1973, Govindarajalu 1974, Wills et al 1980, Rodrigues and Estelita 2002, Alonso and Moraes-Dallaqua 2004, Menezes et al 2005, Lima and Menezes 2009.…”

“…In the two species from this study, the adventitious roots originated from the pericycle in the rhizome, an occurrence that has been described to other Cyperaceae species (Leite et al 2009, Lima andMenezes 2009) and monocotyledons (Menezes et al 2005, Cattai andMenezes 2010). The study of the presence of the pericycle in other organs, not including the root, has often been neglected (Menezes et al 2005).…”

“…In addition to forming adventitious roots, the pericycle in the rhizome of Cyperus laxus and Fimbristylis dichotoma, as in other monocotyledons, originates vascular plexus, promoting the vascular connection between the roots and rhizome (Simão and Scatena 2001, Alonso and Moraes-Dallaqua 2004, Menezes et al 2005, Lima and Menezes 2009. For the species in this study, during the formation of adventitious roots, we observed that there was continuity between the root and rhizome of the vascular tissues and of the endodermis and pericycle.…”

“…In general, studies on anatomical development are restricted to a description of only one organ, such as the roots in Cyperus giganteus (Rodrigues and Estelita 2004); rhizomes in Cyperus esculentus (Bendixen 1973), Cyperus giganteus (Rodrigues and Estelita 2002) and Scleria (Lima and Menezes 2009); and leaves in Cyperus eragrostis (Soros and Dengler 1996) and Cyperus giganteus (Rodrigues and Estelita 2003).…”

“…In studies of development, only Menezes et al (2005) and Lima and Menezes (2009) refer to the continuity of the tissues, which is marked by the presence of the endodermis and pericycle in all vegetative organs (Menezes et al 2005). The endodermis and pericycle are structures that are often related to roots (Esau 1965); however, there are a few reports of these structures being present in other organs, such as the stem and leaf (Lersten 1997, Menezes et al 2005.…”