In contrast to most animals, plants have an indeterminate body plan, which allows them to add and accumulate new body parts during their lifetime. A plant’s realized modular construction is the result of external constraints and internal processes.
The phylogenetic distribution of plant growth forms across the phylogeny implies that body architectures have originated and been lost repeatedly, being shaped by a limited set of genetic pathways. Chomicki et al.:
- synthesize concepts of plant architecture, so far captured in 23 models.
- extend them to the fossil record.
- summarize what is known about their developmental genetics.
- use a phylogenetic approach in several groups to infer how plant architecture has changed and by which intermediate steps.
- discuss which macroecological factors may constrain the geographic and ecological distribution of plant architectures.
This synthesis highlights the architectural diversity of dichotomously branched Paleozoic plants, and the subsequent replacement of dichotomy by axillary branching. Plotting the frequency of branching types through time based on an analysis of 58 927 land plant fossils revealed a decrease in dichotomous branching throughout the Devonian and Carboniferous, mirrored by an increase in other branching types including axillary branching. The authors suggest that the evolution of seed plant megaphyllous leaves enabling axillary branching contributed to the demise of dichotomous architectures.
It also pinpoints the gaps in our understanding of the molecular control, ecology and evolution of plant architecture.