Abstract
Dicranophyllum gallicum Grand’Eury is described by means of a morphometric analysis of eighty two samples from various old and new localities in western and central Europe. Stem, leaf cushions, leaf scars, leaves, axillary structures and potential seeds are described in detail, and discussed in comparison to earlier studies. The encountered variability in size and structure is shown to be higher than what was described earlier. The organisation of the leaf cushion and scar density vary gradually with the stem width, while stratigraphic position and ecology do not relate to it. It is concluded that the described variability represents an ontogenetic feature rather than a phylogenetic or ecologic one. The juvenile plants are characterised by small stems, a high leaf scar density and elongated leaf cushions with a dominant apical field, while mature specimens are characterized by a wide stem, a relatively low leaf scar density and relatively wide leaf cushions with a pronounced basal field. Axillary shoots and potential seeds of D. gallicum are described and illustrated in detail for the first time. A reconstruction based on the studied material is presented.
Highlights
Dicranophyllum gallicum Grand’Eury (1877) is a characteristic species of the late Mississippian to early Permian of Euramerica (Wagner 2005)
Dicranophyllum gallicum variatio parchemineyi was described by Renault and Zeiller (1888) to have a double row of small conical seeds attached to the unbifurcated base of the leaf (Renault and Zeiller 1888)
For our reconstruction of D. gallicum, we propose that the plant had a simple, unbranched stem, which reached 4.5 meters in height (Fig. 12)
Summary
Dicranophyllum gallicum Grand’Eury (1877) is a characteristic species of the late Mississippian to early Permian of Euramerica (Wagner 2005). The genus is typified by bifurcating leaves, inserted on the stem in helical arrangement, forming rhomboidal leaf cushions (Grand’Eury 1877). It has characters reminiscent of several higher taxonomic. Jorik Van Der Pas et al / PhytoKeys 88: 123–149 (2017). Dicranophyllum gallicum Grand’Eury, the type species of the genus, is characterized by short, tough leaves bifurcating twice, with a central vein and two lateral stomatiferous furrows (Barthel 1977, Meyen and Smoller 1986). Dicranophyllum gallicum variatio parchemineyi was described by Renault and Zeiller (1888) to have a double row of small conical seeds attached to the unbifurcated base of the leaf (Renault and Zeiller 1888)
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