Pair-flowered cymes in the Lamiales: structure, distribution and origin

Abstract

From the exclusive occurrence of PFCs in the Lamiales and the proximity of the respective taxa in molecular phylogenies it may be expected that PFCs have originated once, representing a synapomorphy for this group of taxa and fading out within the Plantaginaceae. However, molecular evidence is ambiguous. Depending on the position of Peltanthera (depending in turn on the kind and number of genes and taxa analysed) a single, a double (the most probable scenario) or a triple origin appears conceivable.

Floral anatomy and vegetative development in Ceratophyllum demersum: A morphological picture of an “unsolved” plant

“…A decussate phyllotaxy is widespread among angiosperms, even in groups remote from Ceratophyllum , such as Lamiales (Weber, 2013). The phyllotaxy of Ceratophyllum , however, appears very specific because the leaves are fused and their shapes are specialized (dissected) and the associated vegetative bud at each node typically forms a zigzag line (90–270–90 divergence), most likely as adaptations to the aquatic environment.…”

Morphological diversity and evolution of Centrolepidaceae (Poales), a species‐poor clade with diverse body plans and developmental patterns

“…At first glance, the variation in number of flower rows found in Centrolepis suggests a comparison with pair‐flowered cincinni. Pair‐flowered cymes, which are probably restricted to certain members of the eudicot order Lamiales (Weber, 2013) have axes of all orders ended in a pair of flowers rather than a flower. Compact cincinni of Epithema Blume (Gesneriaceae, Weber, 1976: fig.…”

“…Four rows of flowers should be also expected in a geminiflorous cincinnus. A geminiflorous cyme is a special type of cyme with one of the two dichasial branches reduced to a single flower (Weber, 2013). In theory, a pattern with three rows of flowers can be found when geminiflorous (or pair‐flowered) cymes are alternating regularly with normal cymes along a cincinnus, but this would be an extremely complex explanation.…”

Morphological and ontogenetic studies with inflorescences and flowers of Lepidagathis Willd. (Acanthaceae)

“…In the Barleria clade, there was a transition of the apical meristem from its Following the molecular inference of Glover et al (2015), losing or gaining a feature is equally likely in an evolutionary scenario, because at the molecular level both changes have the same probability of taking place. According to Weber (2013), in the Lamiales there has been a passage from determinate to indeterminate inflorescences, meaning the loss of the terminal flower on the main axis. Nonetheless, within the indeterminate inflorescences, there has been a gain in branching growth, as the secondary axes, which were formerly solitary flowers, may become cymes, by the activity of reproductive meristems, giving rise to thyrses.…”