A Commentary on a Diagrammatic Presentation of the Angiosperms in Relation to the Distribution of Character States

Abstract

The difficulty, not to say impossibility, of presenting groups of orders as variously shaped figures in a two-dimensional diagram to indicate relationships is first emphasized. However, the method can be used to demonstrate the distribution of character states. The distributional patterns of a number of character states are presented with brief comments, viz. sympetaly, epigyny and perigyny, centrifugal succession in multi-staminate androecia, pollen grains with one aperture, the successive type of microsporogenesis, apocarpy, three-nucleate pollen grains (the “dry” stigmas and the C₄ pathways being largely correlated with this attribute), unitegmic and tenuinucellate ovules and cellular and helobial types of endosperm formation. In addition, the distribution in dicotyledons is outlined for the synthesis of ellagic acid, iridoids, benzylisoquinoline alkaloids, glucosinolates and polyacetylenes derived from fatty acids. In monocotyledons other characters prove useful in gross taxonomy, for instance the presence of vessels in the stem, the presence of starch in the endosperm and the presence of oxalate raphides and silica bodies, as well as more conventional characters such as floral symmetry, epigyny versus hypogyny, stamen number and fruit type. Comments on the possible taxonomic significance of the characters shown are included. An apparent connection between certain constellations of orders (superorders) is pointed out. Finally, an appeal is made for further cooperation in presenting the distribution of other character states which may be of taxonomic importance at the higher levels.