The application of numerical methods to the taxonomy of Spermatophyta: with evaluation of the taxonomic implications of the results

543 genera of Dicotyledons are recorded for available comparative data on floral and vegetative morphology, anatomy, cytology, palynology and embryology, and this is analysed under three different numerical methods (INFO, ASOC and MULASS). A comparison of the results throws light on the high-level taxonomy of Dicotyledons; the currently unfashionable polypetalous/sympetalous dichotomy is strongly supported by all analyses and on the basis of available evidence seems a fully justified primary division of the group. Within the polypetalous subgroup 'magnolioid', 'caryophylloid' and 'celastroid' circles of affinity are recognised, but equally significantly many genera cannot be satisfactorily placed on the basis of the information despite their apparent positions in most published systems, suggesting a desperate need for more careful examination and recording of features to allow a taxonomic reassessment at this level. The smaller and more closely defined sympetalous grouping is split into the 'Aaclepioids', 'Acanthoids', Compositae and Umbelliferae.<br/><br/>Pilot analyses on anatomical data for hardwoods and softwoods are also considered. In the former case the interrelationships of the three subfamilies of Leguminosae are questioned, The Caesalpinioideae, regarded by phylogenists as the most primitive, appear in terms of wood anatomy to be 'intermediate' between the Mimosoideae and Papilionoideae, confounding the phylogenetic ideas. In the case of the softwoods a hitherto unsuspected major dichotomy between the Pinaceae and the remaining families is suggested and supported by external evidence; within the latter grouping the geographic split into northern and southern forms, originally based on fossil evidence, is backed up anatomically.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

1969

Author dc:creator

• Young, David John