Evidence-based 3D reconstructions separate three axis types in Asteroxylon mackiei and show an extinct anisotomous route to rooting axes without projecting that anatomy onto all lycophytes.
Three-dimensional reconstructions of the approximately 407 Ma Rhynie-chert lycopsid Asteroxylon mackiei distinguish leafy shoot, root-bearing and rooting axes and show rooting axes arising at anisotomous branch points; this is a species-level body-plan exemplar, not a trait assertion for all Lycophyta.