Stem anatomy and development of successive cambia in Hebanthe eriantha (Poir.) Pedersen: A neotropical climbing species of the Amaranthaceae

Hebanthe eriantha (Poir.) Pedersen, a climbing species of the Amaranthaceae increases in stem thickness by forming successive cambia. The family is dominated by herbaceous species and is constantly under discussion due to its disputed nature of the meristem. In the young stem small alternate segments of vascular cambium cease to divide and new arc of cambium initiates outside to it. The newly formed arcs connect with pre-existing alternate segments of cambium to complete the ring. On the contrary, in thick stems, instead of small segments, complete ring of cambium is replaced by new one. These new alternate segments/cambia originate from the parenchyma cells located outside to the phloem produced by previous cambium. Cambium is storied and exclusively composed of fusiform initials while ray cells remain absent at least in the early part of the secondary growth. However, large heterocellular rays are observed in 15-mm diameter stems but their frequency is much lower. In some of the rays, ray cells become meristematic and differentiate into radially arranged xylem and phloem elements. In fully grown plants, stems are composed of several successive rings of secondary xylem alternating with secondary phloem. Secondary xylem is diffuse-porous and composed of vessels, fibres, axial parenchyma while exceptionally large rays are observed only in the outermost regions of thick stems. Vessel diameter increases progressively from the centre towards the periphery of stems. Although the origin of successive cambia and composition of secondary xylem of H. eriantha remains similar to other herbaceous members of Amaranthaceae, the occurrence of relatively wider and thick-walled vessels and large rays in fully grown plants is characteristic to climbing habit. © 2013 Springer-Verlag Wien.

Informe de la Reunión Regional para América Latina y el Caribe Preparatoria de la Conferencia de las Naciones Unidas sobre el Medio Ambiente y el Desarrollo = Report of the Latin American and Caribbean Regional Preparatory Meeting for the United Nations Conference on Environment and Development

Contiene la asistencia, organización de los trabajos y resumen de los debates de la reunión en la que se examinó, desde una perspectiva de los países de América Latina y el Caribe, tres aspectos interrelacionados: el vínculo entre el desarrollo económico y la sustentabilidad ambiental, los fenómenos ambientales que afectan a la región con los fenómenos ambientales globales, y el vínculo entre defensa ambiental y desarrollo económico en el contexto de la cooperación internacional.

La protección y el manejo de océanos, mares y zonas costeras en la Plataforma de Tlatelolco sobre Medio Ambiente y Desarrollo: un análisis práctico de sus alcances = The protection and management of oceans, seas and coastal areas under the Tlatelolco Platform on Environment and Development: a practical analysis of its implications

Incluye Bibliografía

Economic criteria for the selection and development of power stations and electricity systems

Includes bibliography

El crecimiento de la población de América Latina y las primeras etapas de las políticas de población: su influencia sobre los problemas de la juventud y el desarrollo = Population growth and the first stages of population policy in Latin America: effect on problems of youth and development

Incluye Bibliografía

Education and development in Latin America

Includes bibliography