The arborescent Linopteris obliqua plant (Medullosales, Pennsylvanian)

Abstract

The foliar morphospecies Linopteris obliqua (Bunbury) Zeiller, 1899 was originally based on isolated pinnules from Middle Pennsylvanian (upper Westphalian) strata in the Sydney Coalfield in Nova Scotia, Canada. However, new finds from the type area, including segments of a cauline axis and some fronds, attached juvenile croziers, an attached ovule, and associated pre-pollen organ, allow for a more complete understanding of the whole Linopteris obliqua plant. It was arborescent, 9 m to 10 m tall, with fronds ca 7 m long. Ovules of the Hexagonocarpus-type were attached directly to the petiole near the base of the frond, and pre-pollen was produced by Potoniea-type structures. The plant produced seeds and pollen at different times to avoid self-pollination. Ovule production was periodic and accompanied by mass pinnule abscission. The venation, especially the areolate-vein geometry, is relatively invariable within the plant species, and thus provides the typus (blueprint) for distinguishing other linopterid species, especially when combined with two-dimensional probability surfaces, and traditional pinnule morphology. However, the venation must be viewed on the abaxial surface of the pinnules if it is to be reliably interpreted. The mode of vein reticulation is shown to be quite distinct from the anastomosis-pattern seen in the other medullosalean taxa, and is another character that separates the Potonieaceae from the rest of the order

Revision of the Pennsylvanian Flora from Val Sanagra in Western Part of the Southern Alps (Italy)

“…The association of pinnules of different shapes indicates that these pinnules come from the same species, but from different parts of the plant. This phenomenon is also shown in Zodrow et al (2007). Figure 1 on the Plate XVII shows two poorly preserved pollen organs in organic connection to a rachis with some Linopteris obliqua pinnules still attached.…”

“…The pinnules identified as L. neuropteroides are mixed with pinnules, which are referred to L. obliqua on the same specimen. Venation diagrams of the pinnules made by camera lucida show some differences between pinnules preserved showing the adaxial and abaxial sides, as already described by Zodrow et al (2007). Due to this fact we assume that only one linopterid species inhabited the original environment.…”

“…Remarks: Linopteris obliqua stratigraphically ranged from lower Moscovian (Uppermost Duckmantian) (Fissunenko and Laveine, 1984) to Uppermost Moscovian (Asturian) (Zodrow et al, 2007). Specimen B1714 shows a very interesting pinnule form with anastomosed venation, with the linesof-areolate.…”

“…(Plate XVII, Fig. 2) One specimen compares with the Hexagonocarpus figured by Zodrow et al (2007, fig. 23, A).…”

A Marine Incursion In the Lower Pennsylvanian Tynemouth Creek Formation, Canada: Implications For Paleogeography, Stratigraphy and Paleoecology

“…Slender upright trees, rooted in ostracod-rich gray shale (Unit 3), are most likely medullosalean pteridosperms given their close association with the foliage of Alethopteris, Laveineopteris, and Paripteris. These three genera (or their close relatives) have been reconstructed as small trees and shrubs (Pfefferkorn et al, 1984;Shute and Cleal, 2002;Zodrow et al, 2007), consistent with the observed woody stumps, and the same three genera have been interpreted as fringing coastlines in the Lower Pennsylvanian Lancaster Formation ('Fern Ledges') in New Brunswick (Falcon-Lang and Miller, 2007). To what degree this medullosalean-dominated coastal vegetation was saline-tolerant is uncertain (Stull et al, 2012) rhomboideus shares features with some progymnosperms, and "S." valida is similar to the putative noeggerathialean Palaeopteridium michiganensis (cf.…”