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Early horsetail ancestor
Early horsetail ancestor
Pseudobornia ursina is a Late Devonian plant that is similar both vegetatively and reproductively to other equisetophytes (i.e., Equisetales, Sphenophyllales). Due to these features and its geological age, Pseudobornia has been considered a stem equisetophyte, or sister to this clade. It is the only taxon in the Pseudoborniales.
Ecology & Form
Ecology & Form
Vegetative features similar to Equisetales; Reproductive parts are similar to the Sphenophyllales
Stems
Stems
Distinct nodes and internodes
Basal nodes produce 1-2 first-order branches up to 3 m long
Second-order branches are opposite and decussate
Higher-order branches emerge in pseudo-distichous pattern
Pseudomonopodial or monopodial branching
15-20 meters tall
Anatomy is unknown
Leaves
Leaves
Originally called meiophylls
Produced only on high-order branches
Highly dissected leaflet attached to twice-dichotomous petiole
Roots
Roots
Underground portions unknown
Reproduction
Reproduction
Fertile branches up to 30 cm long
Each fertile unit exhibits whorled bracts and sporangiophores
Sporangiophores have upturned tips divided into two segments
Each sporangiophore has ~30 sporangia
Classification
Classification
└Equisetophytes
└Pseudoborniales †
Geologic Age
Geologic Age
Late Devonian
Diversity
Diversity
Pseudobornia ursina † (Schweitzer, 1967)
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