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Ancestral cone-bearing plants
Ancestral cone-bearing plants
Cordaites were seed-bearing plants with loose cones and strap-like leaves. They were important components of the Euramerican forests during the Late Paleozoic. There was a high diversity of cordaites in the cool temperate forests of the Russian-Siberian Platform. Some inhabited swamp-like conditions, exhibiting mangrove-like growth. This group has some affinity to modern conifers and may represent some of the earliest cone-bearing plants on Earth.
Geologic Range
Geologic Range
Diversity
Diversity
Cordaites †
Ecology & Form
Ecology & Form
Stems
Stems
Pycnoxylic woody stems with substantial pith
Stems had a septate pith, in the form genus Artisia
Woody stems with biseriate rays (Mesoxylon †) and uniseriate rays (Cordaixylon †)
Large stem pieces are known as Dadoxylon † and Pennsylvanioxylon †
The cordaites may have produced the earliest known amber found in the fossil record
Above: Artisia wood with septate pith
Leaves
Leaves
Strap-shaped morphology with parallel venation
Leaves were probably thick and leathery in texture
In cross-section, leaves have "I-beam" morphology created by bundles of sclerenchyma fibers above and below the vascular strands
Roots
Roots
The roots and protostelic and eustelic, in the form genus Amyelon †
Mycorrhizal fungi have been reported in the primary roots
Above: Amyelon wood found roots
Above: Cordaites † leaf compressions, showing strap-like morphology and parallel veins
Below: cross-section of Cordaites † leaf showing parallel veins and I-beam anatomy around bundles
Reproduction
Reproduction
Cordaianthus †
The form genus for both the ovule-bearing and pollen-bearing structures of this plant
This structure consisted of a primary axis with secondary shoots, which lie in the axils of modified leaves (bracts)
Each secondary shoot has spirally arranged scales, most of which are sterile, but which may bear pollen sacs or ovules on short stalks.
Cordaianthus has possible homologies with the ovule-bearing cone of conifers, inwhich a bract subtends the scales or shoots in the cone.
The ovules are heart-shaped, in the form genus Cardiocarpus † or Mitrospermum †
Florinanthus bussacensis †
Lower Gzhelian (Upper Pennsylvanian) Vale da Mó “Formation” of the Buçaco Carboniferous Basin, central western Portugal
Adpression of male cones is probably produced on the same parent plant as female cones
Pollen sacs grouped in 4 to 5 clusters, composed of 4–7 basally fused sacs, and ovate to lanceolate-shaped sterile scales.
Above: Reproductive structures of Cordaites. (A) Foliage with fertile shoots. (B) Portion of the ovule-bearing Cordaianthus including part of the primary axis with ovulate secondary shoots bearing pendant ovules. (C) Pollen-bearing Cordaianthus including part of the primary axis with secondary fertile shoots, each of which is a compound structure with bracts subtending pollen organs.
Above: Cardiocarpus † seed
Above: Cordaianthus † "cone"
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