Stem and root anatomy of two species of Echinopsis (Trichocereeae, Cactaceae)

Abstract

This study characterizes and compares the stem and root anatomy of Echinopsis calochlora and E. rhodotricha (Cactaceae) occurring in the Central-Western Region of Brazil, in Mato Grosso do Sul State. Three individuals of each species were collected, fixed, stored and prepared following usual anatomy techniques, for subsequent observation in light and scanning electronic microscopy. Echinopsis calochlora revealed uniseriated epidermis, while E. rhodotricha had patches of bisseriated epidermis; all species showed thick cuticle, parallelocytic stomata at the epidermis level, and a well-developed hypodermis. Cortical and medullary bundles are present in the studied species, as well as mucilage cells in the cortex region. The secondary phloem is composed by sieve tube elements, companion cells, axial and radial parenchyma. Sclereids were found at the outer regions of phloem in the roots. The secondary xylem is non fibrous in the stems of E. calochlora, and fibrous in the stems of E. rhodotricha and in the roots of both species. Many of these characteristics are commonly found in Cactaceae, and represent important adaptations for survival in xeric environments.

Anatomical and morphological features of seedlings of some Cactoideae Eaton (Cactaceae Juss.) species

“…Adult plants of the subfamily Cactoideae also have typically a uniseriate epidermis, which in some species has a thickened outer wall and a thick cuticle. Moreover, these plants have a multiseriate hypodermis [9,19,31,32]. In this work, a uniseriate hypodermis with calcium oxalate prismatic crystals and druses was found only in two species -E. peruviana and A. myriostigma.…”

“…It is green and photosynthetic. The chlorenchyma of Cactoideae adult plants is commonly characterized by multiple layers of palisade cells [9,31,32]. However, in the majority of species studied here, seedlings have a poorly developed chlorenchyma which consists of isodiametric cells, and palisade cells sometimes were only observed in A. myriostigma and R. minuscula seedlings.…”

“…Most anatomical studies concerning the subfamily Cactoideae are focused on adult plants [7][8][9][10][11]. According to Terrazas and Arias [10], about 350 species of the subfamily have already been investigated.…”

Caracteres anatómicos y fitoquímicos del tallo y raíz de Mammillaria uncinata (Cactaceae)

“…La cutícula tiene una función importante al constituir una barrera primaria entre el cuerpo de la planta y las condiciones ambientales (Salinas-Revilla y Álvarez-Moscoso, 2006). La epidermis uniestratificada de células con pared delgada y lisa coincide con observaciones realizadas para especies de otras cactáceas (Muruaga y Guantay, 2011;dos Santos García et al, 2012;Gonçalves da Silva et al, 2013). En otras especies de Mammillaria (M. polythele Mart.…”

“…La subfamilia Cactoideae comprende el mayor número de especies y es la más diversa en términos de hábitos de crecimiento y formas de vida; se divide en nueve tribus: Browningeae, Cacteae, Calymmantheae, Cereeae, Hylocereeae, Notocacteae, Pachycereeae, Rhipsalidae, Trichocereeae (Ortega-Baes et al, 2010;dos Santos et al, 2012;Vázquez-Sánchez et al, 2012). En la tribu Cacteae, por ejemplo, predominan géneros como Aztekium Boed.…”