A three-dimensional reconstruction is provided of the composition, spatial distribution, and structure of a single-aged, Middle Pennsylvanian (Moscovian) peat-forming forest of a high-ash, planar (rheotrophic) mire, buried in situ by volcanic ash and preserved in the Lower Radnice Coal of the Radnice Basin (Czech Republic). The reconstruction is based on a detailed taxonomic and taphonomic analysis of fossils in a ∼0.5-m-thick tuff bed at the base of the Whetstone Horizon excavated over an area of 93.5 m². In all, 24 whole-plant taxa of various growth forms were identified. This assemblage represents a lepidodendrid- and Cordaites borassifolius-dominated forest, with a well-developed understory of subarborescent lycopsids, tree ferns, medullosan pteridosperms, and calamites, as well as herbaceous ground cover. Lycopsids were dominated by Lepidodendron simile bearing Flemingites-type cones and L. lycopodioides; Lepidophloios cf. acerosus was subdominant. Lianas, mostly lyginopterid pteridosperms and some ferns, were usually found close to upright stems. The ground cover, mostly ferns and sphenophyllaleans, was taxonomically the most diverse stratum, although only a minor contributor to the peat. Based on samples from the coal roof, the palynological record is in agreement with the tuff bed assemblage except for the quantity of certain taxa. To reduce this bias, compression R-values were calculated from the percent cover of aerial plant parts in the excavation and in the dispersed palynoflora. These R-values suggest that in the palynological record, arborescent lycopsids and sphenophylls are greatly overrepresented, ferns and cordaites strongly underrepresented, and calamites are almost the same in both records.