Development of lateral meristem and pattern of secondary growth in stems and roots of Spinacia oleracea Linn (Amaranthaceae)

Abstract

Development of lateral meristem and pattern of secondary growth in the stems and roots of Spinacia oleracea Linn (Amaranthaceae) were studied anatomically. Maturing stems and roots increased in thickness by developing successive rings of cambia which produce secondary vascular elements embedded in the groundmass of thin walled parenchymatous conjunctive tissues. Second ring of the cambium was originated outside the first ring of the cambium and gave rise to parenchyma cells and sieve tube elements on the outer side whereas it gave rise to conjunctive tissue and secondary xylem on the inner side. Prior to the development of second ring of cambium, parenchyma cells located outside to the previous cambium dedifferentiated and acquired meristematic property which led to the formation of meristematic bands of radially arranged cells. Later on each successive ring of cambium developed in similar fashion as described above. The groundmass of the stems and roots was mostly composed of thin walled conjunctive tissue on both the outer and inner side of each cambium, whereas formation of thick walled conducting elements of secondary xylem and secondary phloem remained restricted to the small segments of the vascular cambium. Secondary xylem was composed of vessel elements, tracheids and libriform fibres whereas secondary phloem comprised of sieve tube elements, companion cells and axial parenchyma with no typical rays even in the mature stems. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Continuity of Procambium and Anomalous Cambium During Formation of Successive Cambia in Celosia argentea

“…These findings prove (3) the presence of developmental continuum of procambium-cambium in Celosia argentea. It would be interesting to analyze in the future whether the mechanism presented here is universal and involved in formation of the successive cambia in other species, both with separate concentric cylinders (Balfour 1965;Terrazas et al 2011;Rajput et al 2010Rajput et al , 2013 and with reticulate network (Schmitz et al 2008;Robert et al 2011). In the latter case, the development of the connections between successive cylinders would be particularly worth analyzing.…”

“…An interesting example of anomalous secondary growth is the activity of several cylinders of meristematic cells, so-called successive cambia (Balfour 1965;Bailey 1980;Fahn and Zimmermann 1982;Carlquist 1988;Rajput et al 2010;Heklau et al 2012). Upon development of successive cambia, the first meristematic cylinder develops either typically, from fascicular and interfascicular cambium, or is established de novo outside the primary vascular bundles, which remain discrete (Balfour 1965;Studholme and Philipson 1966;Bailey 1980;Tamaio et al 2009;Terrazas et al 2011;Rajput et al 2012).…”

Anatomia de raízes e caules de Bignonieae: síndrome lianescente e xilema secundário

“…Apesar de comuns em caules de diversas espécies de lianas, principalmente por sua conexão com o hábito, as variações cambiais ocorrem também nas raízes, de forma semelhante aos caules, em vários grupos de plantas, como Amaranthaceae, Basellaceae, Nyctaginaceae, Passifloraceae, Phytolaccaceae, Polygonaceae e Sapindaceae (Grosso 2007;Rajput et al, 2010;El-Ghamery et al 2015;Carlquist 1999;Carlquist 2004;Hearn 2009;Mikesell 1979;Horak 1981;Rajput 2015). Os trabalhos de Gabrielli (1992), Martinelli et al (2008) e Singh & Misra (2012) demonstram que também as raízes de espécies de Bignonieae desenvolvem cunhas de floema semelhantes às encontradas em caules, entretanto esses estudos se mostram rasos ou incompletos quanto a maiores aspectos anatômicos e estruturais.…”