Radial secondary growth and formation of successive cambia and their products inIpomoea hederifoliaL. (Convolvulaceae)

Abstract

Ipomoea hederifolia stems increase in thickness using a combination of different types of cambial variant, such as the discontinuous concentric rings of cambia, the development of included phloem, the reverse orientation of discontinuous cambial segments, the internal phloem, the formation of secondary xylem and phloem from the internal cambium, and differentiation of cork in the pith. After primary growth, the first ring of cambium arises between the external primary phloem and primary xylem, producing secondary phloem centrifugally and secondary xylem centripetally. The stem becomes lobed, flat, undulating, or irregular in shape as a result of the formation of both discontinuous and continuous concentric rings of cambia. As the formation of secondary xylem is greater in one region than in another, this results in the formation of a grooved stem. Successive cambia formed after the first ring are of two distinct functional types: (1) functionally normal successive cambia that divide to form secondary xylem centripetally and secondary phloem centrifugally, like other dicotyledons that show successive rings, and (2) abnormal cambia with reverse orientation. The former type of successive rings originates from the parenchyma cells located outside the phloem produced by previous cambium. The latter type of cambium develops from the conjunctive tissue located at the base of the secondary xylem formed by functionally normal cambia. This cambium is functionally inverted, producing secondary xylem centrifugally and secondary phloem centripetally. In later secondary growth, xylem parenchyma situated deep inside the secondary xylem undergoes de‐differentiation, and re‐differentiates into included phloem islands in secondary xylem. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158, 30–40.

Variante cambial en tallos de Ipomoea (Convolvulaceae) nativas de Argentina.

“…Estos forman numerosos anillos sucesivos de xilema, floema y tejido conjuntivo de células parenquimáticas, siendo estos anillos discontinuos, formando haces o fascículos. Este tipo de crecimiento anómalo es el más frecuente en el género (Metcalfe & Chalk, 1950), y fue reportado en especies de trepadoras anuales (Lowell & Lucansky, 1986;Rajput et al, 2008), y en enredaderas, árboles y arbustos de la serie Arborescentes, aunque en estas sólo se analizaron los leños de plantas adultas (McDonald, 1992;Ceja-Romero & Pérez-Olvera, 2010). Nuestras observaciones no coinciden con lo reportado anteriormente por Chen et al (2007), ya que ellos indicaron que I. cairica no presenta crecimiento secundario desarrollado.…”

“…Por ejemplo, en el patrón foraminado se forman pequeñas lagunas de floema incluidas en el xilema, a partir de cámbiumes intraxilares, (Lowell & Lucansky, 1986Rajput et al, 2008Rajput et al, , 2013. Además se ha reportado el desarrollo de cámbiumes con orientación invertida, que originan xilema centrífugamente y floema centrípetamente (Rajput et al, 2008;Terrazas et al, 2011).…”

“…Por ejemplo, en el patrón foraminado se forman pequeñas lagunas de floema incluidas en el xilema, a partir de cámbiumes intraxilares, (Lowell & Lucansky, 1986Rajput et al, 2008Rajput et al, , 2013. Además se ha reportado el desarrollo de cámbiumes con orientación invertida, que originan xilema centrífugamente y floema centrípetamente (Rajput et al, 2008;Terrazas et al, 2011). La aparición de cámbiumes internos entre el xilema primario y el floema interno, y que producen haces vascular invertidos (Lowell & Lucansky, 1990;Rajput et al, 2008;Patil et al, 2009).…”

“…A pesar de los numerosos estudios en este género, escasos son los trabajos realizados sobre la ontogenia de tallos (Lowell & Lucansky, 1986Rajput et al, 2008;Terraza et al, 2011), fundamentales para comprender el desarrollo de los distintos tipos de variante cambial. Por ello, se planteó el estudio de la ontogenia, anatomía y desarrollo de enredaderas nativas de Argentina, y de I. carnea ssp.…”

Origin of successive cambia on stem in three species of Menispermaceae

“…In fact, there are more detailed studies on the following families: Amaranthaceae, Aizoaceae, Chenopodiaceae, Leguminosae, Nyctaginaceae, Convolvulaceae and Phytollacaceae. In these families, the pattern of secondary thickening is only superfi cially similar to Menispermaceae, and the literature has proposed different origins for successive cambia: cortex (Pfeiffer 1926, Chalk & Chattaway 1937, Balfour 1965, Mikesell & Popham 1976, Mikesell 1979, Carlquist 1999, 2007, Rajput & Rao 2008, pericycle (Haberlandt 1914, Pfeiffer 1926, Chalk & Chattaway 1937, Joshi 1937, Mikesell & Popham 1976, Mikesell 1979, Fahn & Zimmermann 1982, phloem (Metcalfe & Chalk 1950, Wheat 1977, Nair & Ram 1990). …”