With one volume each year, this review series keeps scientists and advanced students informed of the latest developments and results in all areas of the plant sciences.
Starting with this volume, the sections of PROGRESS IN BOTANY have been restructured. The new sections - Genetics - Cell Biology and Physiology - Systematics and Comparative Morphology - Ecology and Vegetation Science - correspond to the subdivision of the field of botany generally used by the scientific community.

The Caryophyllales are one of the few higher taxa of the flowering plants ofwhich the size and delimitation against other taxa is undisputed. However, their derivation from other taxa and the evolution of families within this order in unsettled. "Systematics and Evolution of the Caryophyllales" reviews the important characters of this taxon emphasizing their contribution and influence towards a new proposal for both the putative origin of the order and the classification of its families. New results in molecular genetics, phytochemistry, ultrastructure, and morphology are provided and discussed in relation to both the classical and molecular systematics of the order. In addition, characters like betalains and sieve-element plastids, which have played a major role in shaping the size of the order, and others like DNA-data or flower morphologythat can be useful to discuss the position of the Caryophyllales within higher plants are critically evaluated.

As part of his Comparative Investigations of the Organization of the Trunk of the Native Forest Trees (Theodor Hartig 1837, Vergleichende Untersuchungen tiber die Organisation des Stammes der einheimischen Waldbaume. lahresberichte tiber die Fortschritte der Forstwissenschaften und forstlichen Naturkunde 1: 125-168) Hartig gives an anatomical description of the "composition and nature" of the then "completely uninvestigated elementary organs" of what he called the "sap skin" (Safthaut) of trees, a tissue for which Nageli later (1858) coined the term phloem. Within the "Safthaut" Hartig describes three cell types in detail, (1) "Siebfasern", (2) "Siebrohren", and (3) "keulenfOrmige Saftrohren" (club-shaped sap-tubes). While the description of the latter refers to laticifers in Euphorbia and resin ducts in Acer and Robinia. "Siebfasern" and "Siebrohren" comprise the sieve elements. A literal translation of the more significant parts of the description of these cell types demonstrates that his "Siebrohren" entirely correspond to what has later been defined as "sieve tubes" but that his "Siebfasern" are less well- defined and in addition to what we call "sieve cells" also include small sieve tubes as well as spindle-shaped cells of cambium, phloem parenchyma and sclerenchyma. Both in his "Siebfasern" and "Siebrohren" Hartig describes sieve areas (his expression is "lense-shaped cavities") and sieve pores (Siebporen).