Evolution and ecology of plant architecture: integrating insights from the fossil record, extant morphology, developmental genetics and phylogenies

Abstract

Dichotomously branching Paleozoic plants already encompassed a considerable diversity of growth forms, here captured in 12 new architectural models. 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. We suggest that the evolution of seed plant megaphyllous leaves enabling axillary branching contributed to the demise of dichotomous architectures. The developmental-genetic bases for key architectural traits underlying sympodial vs. monopodial branching, rhythmic vs. continuous growth, and axillary branching and its localization are becoming well understood, while the molecular basis of dichotomous branching and plagiotropy remains elusive. Three phylogenetic case studies of architecture evolution in conifers, Aloe and monocaulous arborescent vascular plants reveal relationships between architectural models and show that some are labile in given groups, whereas others are widely conserved, apparently shaped by ecological factors, such as intercepted sunlight, temperature, humidity and seasonality.

Unusual developmental morphology and anatomy of vegetative organs in Utricularia dichotoma—leaf, shoot and root dynamics

“…This way, each vegetative organ is a specific patchwork of leaf, shoot and root characters, and the developmental fate of its primordium may be triggered by chemical compounds, light, water or other environmental factors (cf. Chomicki et al 2017;Mizutani and Kanaoka 2017;Fritz et al 2018). Our findings in U. dichotoma reinforce previous observations regarding organ interchangeability and fuzzy morphology in terrestrial bladderworts (Brugger and Rutishauser 1989;Rutishauser 2016).…”

Corner's rules as a framework for plant morphology, architecture and functioning – issues and steps forward

“…(b, c) leptocaul beech tree, Fagus sylvatica ); and (d) relationships that determine the correlation space between stem and appendages are initiated in the shoot apical meristem ( SAM ) where cell number positively affects meristem size which, in turn, positively affects stem diameter and leaf area (blue arrows; Schnablová et al ., ). The axillary meristem, which is initiated in the boundary regions between the adaxial base of the leaf primordium and the SAM , is closely associated with leaf polarity and also results from signals from the SAM (yellow arrows; Yang & Jiao, ; Chomicki et al ., ). To what extent leaf and stem size and shape, and axillary production size and fate, are pre‐determined in the SAM or result from later interactions among growing organs needs to be further investigated.…”

“…d; Yang & Jiao, ) suggesting that the growth, and likely fate of the axillary production, is not passive but partly determined by interactions between the SAM and newly initiated organs at a very early stage. This is supported by findings on branch plagiotropy in Araucaria and Coffea likely resulting from an early SAM signal (see discussion in Chomicki et al ., ). However, results obtained on individual metamers of peach (Kervella et al ., ) and apple (Lauri & Térouanne, ) show that the growth dynamics of the leaf or of both the internode and the leaf, respectively, affect the axillary bud fate (namely, latent, vegetative, floral; Lauri & Normand, ).…”

“…Noticeably, Corner's rules were at the origin of the conceptual modeling of whole‐plant architecture developed by Hallé and colleagues on existing species (Hallé & Oldeman, ; Hallé et al ., ), recently extended by Chomicki et al . () on Paleozoic taxa. These rules are still providing a heuristic framework for the quantification of plant form and function at various plant scales (e.g.…”

Morphological (and not anatomical or reproductive) features define early vascular plant phylogenetic relationships

“…B). Among present‐day plants, anatomical and morphological characters are generally highly correlated by virtue of the developmental regulatory systems giving rise to them (Chomicki et al., ). The analyses presented here indicate that anatomical‐morphological correlations appear to hold true for the fossil taxa used in this study.…”