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Early Devonian plant with elaborate branching
Early Devonian plant with elaborate branching
Pertica † is an extinct leafless stem euphyllophyte ("trimerophyte") that was very tall for the time in which it lived (Early Devonian). The plant had distinct nodes and internodes, similar to those of horsetails. Pertica † may be an intermediate taxon between early-branching euphyllophyte forms and woody plants (lignophyte) such as Tetraxylopteris †
Named by Kasper & Andrews (1972) from compression fossils found in the Trout Valley Formation of northern Maine.
In 1985, Pertica was named the state fossil of Maine
Pertica may represent the ancestral member of the radiatopsids and sister to the lignophyte clade
Stems
Stems
This plant was strongly pseudomonopodial with a main upright stem and complex dichotomous branching in lateral axes.
Similar morphology to Psilophyton, but taller (1-3 m in height); probably the largest plants on the Early Devonian landscape
Primary axes have spiral branching, so they appear quadriseriate (branches are four distinct rows)
Distinct internodes between secondary branches
Secondary branches emerging in pairs or near whorls
Subsequent branch orders may be dichotomous or pseudomonopodial
Branches covered in fine enations or hairs.
Anatomy: internal structure unknown due to compression
Leaves
Leaves
No leaves
Reproductive Structures
Reproductive Structures
Axes terminate in clusters of many elongate homosporous sporangia
Diversity
Diversity
Pertica dalhousii †
Eifelian of North America; Canada; New Brunswick; Dalhousie Junction; Near Dalhousie Junction.
Pseudomonopodial main axis
Spiral arrangement of laterals
Pertica quadrifaria †
Eifelian of Trout Valley Formation in Baxter State Park near Mount Katahdin.
Tetrastichous lateral branching may be a step in the evolution of whorled branching.
Pertica varia †
Emsian of Eastern Canada.
Taller than P. quadrifaria, reaching a height of nearly 3 m.
The sporangia were similar to those of P. quadrifaria, although there were fewer in each cluster.
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