Comparative seed morphology and character evolution in the genus Lysimachia (Myrsinaceae) and related taxa

• Published in: Plant systematics and evolution 2008-04, Vol.271 (3-4), p.177-197
• Main Authors: Oh, Il-Chan, Anderberg, A.-L, Schönenberger, J, Anderberg, A. A
• Format: Article
• Language: English
• Subjects: Anagallis; Asterolinon; Biologi; Biological taxonomies; Biology; Biomedical and Life Sciences; Coating; Diagnostic systems; Evolution; Glaux; Life Sciences; Lysimachia; Mapping; Morphology; Myrsinaceae; NATURAL SCIENCES; NATURVETENSKAP; Pelletiera; Phylogenetics; Phylogeny; Plant Anatomy/Development; Plant Ecology; Plant growth; Plant morphology; Plant Sciences; Plant Systematics/Taxonomy/Biogeography; Plants; Primulaceae; Seed coats; Seed dispersal; seed morphology; Seeds; Taxa; Testa; Trientalis
• ISSN: 0378-2697; 1615-6110; 1615-6110; 2199-6881
• DOI: 10.1007/s00606-007-0625-z

We investigated seed morphology in 34 species of the genus Lysimachia and in 14 species and two subspecies of six additional genera (Anagallis, Ardisiandra, Asterolinon, Glaux, Pelletiera, Trientalis), which have been shown to be closely related to, or are placed within Lysimachia in previous molecular studies. We studied seed shape, seed coat structure, and seed coat surface patterns. Three major types of seed shape were identified: (1) sectoroid, (2) polyhedral, and (3) coarsely rugose with concave hilar area. In addition, seeds may be keeled or winged. The outer layer of the seed coat is either sponge-like and adhering only loosely to the inner seed coat or it is thin and tightly adhering to the underlying tissue. Seed surface patterns can be divided into six main types: (1) reticulate, (2) tuberculate, (3) vesiculose, (4) colliculate, (5) undulate, or (6) poroid-alveolate. Seed surface patterns are mostly congruent with molecular phylogenetic relationships. A reticulate surface pattern is diagnostic of, e.g. Lysimachia subgenera Palladia and Hawaiian Lysimachiopsis. Mapping seed characters onto a recent phylogenetic tree, reveals that they provide potentially synapomorphic character states for various subclades of Lysimachia. Salient examples include a rugose seed shape, which turns out to be synapomorphic for the clade comprising the genus Pelletiera plus Asterolinon linum-stellatum and a sponge-like outer seed coat layer, which characterizes a clade with Lysimachia vulgaris, L. thyrsiflora, and L. terrestris, with an analogue that apparently evolved in parallel in Trientalis europaea. We also discuss possible habitat factors that may have favored the independent evolution of particular seed types such as winged seeds in various lineages.