The distribution and the systematic relevance of the androecial characters oligomery and polymery in the Magnoliophytina

Abstract

. 1987. The distribution and the systematic relevance of the androecial characters oligomery and polymery in the Magnoliophytina.-Nord. J. Bot. 7: 23!2-253. Copenhagen. ISSN 0107-055X.In the system of classification sensu Cronquist, the division between the two subclasses Dilleniidae and Rosidae relies on only a few characters. The major distinguishing character is the occurrence of centripetal or centrifugal sequence of stamen development. We question not only the application and the value of this character, but also the maintenance of the Rosidae and Dilleniidae as separately derived natural taxa, because of the lack of solid distinguishing criteria. We have studied the stamina1 characters in the 192 families of the Dilleniidae and the Rosidae, using Dahlgren's classification diagram. The study focussed on the following androecial characters: 1) polyandry; i.e. spiral polyandry, complex polyandry (viz. centrifugal, centripetal and lateral polyandry) and cyclic polyandry 2) diplostemony and obdiplostemony 3) haplostemony and obhaplostemony .In our proposal only two characters are maintained, namely oligomery (diplostemony s.1.) and polymery (true polyandry %I.), both having a number of character states. Polyandry, as it has been described up to now, is not to be regarded as homologous in all Magnoliophytina. Both characters correspond to two different lines within the Magnoliatae. In addition, the division between the Dilleniidae and Rosidae sensu Cronquist is no longer tenable. Finally, a number of modifications of Dahlgren's diagram are suggested and a division of the Magnoliophytina in a polymerous group and an oligomerous group is proposed. The Dilleniidae-Rosidae complex is included in the oligomerous group.

The major clades of Loasaceae: phylogenetic analysis using the plastid matK and trnL‐trnF regions

“…Most of these authors (Payer, 1857;Hirmer, 1916;Leins and Winhard, 1973;Ronse Decraene and Smets, 1987) suggested splitting taxa with centripetal androecial development (e.g., Mentzelia) from those that have centrifugal androecial development (e.g., Cajophora and Nasa). Such suggestions proved problematic when Hufford (1990) demonstrated that some Loasoideae, including Cajophora and Nasa, purported to have centrifugal androecia actually begin androecial development with a phase of centripetal initiation of stamen primordia.…”

Types of floral nectaries and the concepts ‘character’ and ‘character-state‘-a reconsideration

“…The nectary types 'caduceus' and 'persistent', as well as the feature 'floral nectary' or 'occurrence of a floral nectary' are considered as 'characters'. With additional characterresearch it has also become possible to distinguish between two supplementary types: n. septalia and n. trichoma1ia (Smets 1986(Smets , 1987.…”

Floral anatomy ofCamellia japonica (Theaceae)

“…Corner (1946) discussed the importance of the developmental pattern of the polyandrous androecium, either centrifugal or centripetal for phylogenetic conclusions. Cronquist (1981) referred to stamen fasciculation and its centrifugal initiation as the important diagnostic characteristics of the class Dilleniidae, although Ronse Decraene and Smets (1987) questioned by the application of centrifugal development for distinguishing the Dilleniidae from other members of Magnoliophyta. In surveying 32 known families of centrifugal stamen initiation, Tucker (1972) described the multistaminate condition said that centrifugality, stamen trunk bundles, and fasciculation were correlated, and stated that such androecia derive from multiplication of stamens in the limited meristematic space of the floral receptacle.…”

“…The polyandrous androecia often manifest complex developmental patterns and a characteristic organography, which has found much attention by morphologists (Corner 1946, Hiepko 1964, Leins and Erbar 1991, Ronse Decraene and Smets 1987, Tucker 1972, and others). Corner (1946) discussed the importance of the developmental pattern of the polyandrous androecium, either centrifugal or centripetal for phylogenetic conclusions.…”