Biomechanical Reconstruction of the Carboniferous Seed FernLyginopteris oldhamia: Implications for Growth Form Reconstruction and Habit

Abstract

The mechanical architecture of the Carboniferous seed fern Lyginopteris oldhamia is investigated from development stages including naturally decorticated stems. The growth form shows a relatively long semi-selfsupporting phase of growth, with prolonged retention of the primary outer ''dictyoxylon'' cortex contributing significantly during early and mature growth. The outer cortex is retained on the stem despite significant secondary vascular growth via radial and tangential expansion and proliferation of interstitial parenchyma and longitudinal division of the radial bands of fibers. In the final stages of development, the outer ''mechanical dictyoxylon'' cortex is sloughed from the stem after periderm development in the inner cortex. Loss of the outer cortex results in a decrease in calculated bending stiffness. Calculations of mechanical stem properties based on the overall development indicate for a climber a comparatively stiff mechanical architecture that is comparable with certain types of extant lianas. Mechanisms that allow L. oldhamia to retain and then shed the outer cortex show developmental and mechanical strategies analogous to those of extant climbing plants. The study indicates that relatively sophisticated climbing stem architectures had already evolved by the Late Carboniferous.

Geometry, Allometry and Biomechanics of Fern Leaf Petioles: Their Significance for the Evolution of Functional and Ecological Diversity Within the Pteridaceae

“…By comparison, the parenchyma and the vascular tissues contribute less than 3% to EI largely due to their low elastic moduli (Niklas, 1999b ). Among the surveyed Pteridaceae species, I varied from 0.004 mm 4 in M. gracilis to 1,628 mm 4 in P. podophylla , consistent with earlier data reported for angiosperm and fern leaves (Niklas, 1991 ; Ennos et al, 2000 ; Masselter et al, 2007 ), and unlike the petiole composite modulus ( E composite ), I exerted a strong effect on petiole EI (Figure 10 ). These patterns have been reported in previous studies of leaf and stem biomechanics (Niklas, 1991 ; Rowe et al, 1993 ; Speck and Rowe, 1994 , 2003 ).…”

Dynamic Carboniferous tropical forests: new views of plant function and potential for physiological forcing of climate

“…Quantitative analyses of extinct plants have focused on their biomechanical properties (e.g. Rowe et al ., ; Rowe & Speck, ; Spatz et al ., ; Masselter et al ., ; Wilson & Fischer, ). Using biomechanical and biophysical principles, recent investigations of late Paleozoic plants have included analysis of extinct plant hydraulics (Cichan, ; Wilson et al ., ; Wilson & Knoll, ; Wilson & Fischer, ; Wilson, ; Strullu‐Derrien et al ., ).…”

Evidence of parasitic Oomycetes (Peronosporomycetes) infecting the stem cortex of the Carboniferous seed fernLyginopteris oldhamia

“…New features documented here include the clear presence of hyphal knots and evidence that is suggestive of an haustorium. In Lyginopteris, these are associated with intact parenchyma of the outer cortex, and in the part of the cortex where the parenchyma cells became strained and distorted as secondary tissues developed [36]. Hyphal knots form when hyphae develop within the cortex of the stem and haustoria represent outgrowths from hyphae that penetrate the cell walls of the host but not the cytoplasm in order to absorb nutrients.…”