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Order Peltaspermales
Order Peltaspermales
The Peltasperms are a group of seed plants from the late Paleozoic and early Mesozoic. This group gets its name from the umbrella-like (=peltate) reproductive structure on which the ovules are arranged. These plants were probably vines or shrub-like plants with superficially fern-like foliage.
Ecology & Form
Ecology & Form
Foliage found in the Northern and Southern hemispheres
Stem
Blister-like sub-epidermal swellings
Leaves
Numerous late Paleozoic and Mesozoic foliage types associated with the peltasperms
The main foliage type is a bipinnate frond (Lepidopteris †)
L. strombergensis exhibits small blisters which may be swellings under the epidermis
Pinnules resemble Alethopteris †, with stomata on both sides of leaves
Inserted subopposite or alternate along the rachis
Intercalary pinnules along the rachis between the primary pinnae
Reproduction
Umbrella-like discs with ovules (Peltaspermum †)
No cupules
Whorled on the underside
Discs pinnately-arranged around axis.
Curved micropylar beaks
Microsporophyll (Callipterianthus † or Antevsia †)
Pinnate axis with short branches
Clusters of small elongate pollen sacs fused at the base
Sterile pinnae in proximal portion of the frond; intercalary pinnae on rachis
Classification
Classification
└Peltaspermales †
Geologic Age
Geologic Age
Pennsylvanian (Kerp et al., 2001) – Early Jurassic (Elgorriaga et al., 2019)
Above: Lepidopteris †
Diversity
Diversity
Antevsia †
Arnhardtia †
Auritifolia †
Autunia †
Callipteris †
Comia †
Dichophyllum †
Glenopteris? †
Lepidopteris †
Lodevia †
Madygenia †
Madygenopteris †
Paratatarina †
Peltaspermum †
Permophyllocladus †
Rhachiphyllum †
Scytophyllum †
Sphenocallipteris †
Supaia? †
Tatarina †
Vittaephyllum †
Permophyllocladus polymorphus †
Planate branching shoots of variously connate scale leaves, gradationally transformed into imparipinnate phylloclades by extensive leaf cohesion
Leaves typically distinct on lower (abaxial) side, but reduced to coalescent leaf cushions or marked by suture lines alone on the opposite (adaxial) side
Lateral branches opposite or subopposite spreading at open angle, decurrent, forming pinnae or lobed pinnules of pinnate phylloclades
Ultimate units short elliptical or obovate branchlets with transverse sutures of adherent leaf pairs, distally leaflike, rounded or notched at the apex, reduced to phylloclade pinnules
Phylloclades strongly cutinized, amphistomatic, papillate
Stomata scattered, more numerous abaxially, irregularly oriented, monocyclic. Subsidiary cells, 4–7(6), radial, with proximal papillae
Florin ring distinct
Guard cells small, sunken
Right: Karasev & Krassilov 2007, Permophyllocladus polymorphus: (1) paratype PIN, no. 5139/4, abaxial side of the apical region of a flattened dorsoventral scale-leaved shoot; (2) the same, adaxial side; (3) paratype PIN, no. 5139/3, abaxial side of a shoot with two lateral branchlets; (4) holotype PIN, no. 5139/1, compression of the middle portion of a phylloclade with lateral branchlets; (5) holotype PIN, no. 5139/1, adaxial side of a lateral branchlet; (6) holotype PIN, no. 5139/1, abaxial side; (7) paratype PIN, no. 5139/2, adaxial side of the compression of a lateral branchlet with two rows of scales on the rachis; (8) the same, abaxial side; (1, 2, 6) SEM; (3, 5) LM.
Additional resources
Additional resources
Seed ferns experimented with complex leaf vein networks 201 million years ago, paleontologists find (Phys.org 16Apr 2024)
└Coiro et al., (2024) Parallel evolution of angiosperm-like venation in Peltaspermales: a reinvestigation of Furcula
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