Stauropteridales

Europe, North America

Features

The representatives are small, bushy growing plant. The branching is done in four or two rows ( or quadriseriat biseriat ). There are no flat leaf blades. The Xylemstrang in cross section vierlappig and easy bilaterally. The branch of anatomy is repeated in the branches of higher order. The sporangia are terminal, there are both homosexual as heterosexual spore spore forms are known.

Dissemination

The finds date from the Devonian to Pennsylvanian of Europe and North America.

System

The Stauropteridales are a basal group of ferns. However, they differ significantly from the groups of extant ferns. In the past they were often combined with other groups to Coenopteridales. Several representatives of this order but were identified as representative of the true ferns, while the Stauropteriden as the Zygopteridales be considered as basal. Therefore, they are managed as a separate order, which only consist of a family, the Stauropteridaceae.

They consist of three genera that belong uniquely to order: Stauropteris, Gillespiea and Rowleya.

Stauropteris

In Stauropteris oldhamia the side branches are in pairs. The lateral axis are branched up to six-fold and three-dimensionally, wherein the vascular bundles are becoming smaller. The xylem develops mesarch. Secondary tissue is not known. In the xylem there Leitertracheiden. The phloem is located in the furrows between the lobes of the xylem. At the base of each side of the axis are ( abnormal leaflets ) at Stauropteris oldhamia strongly divided Aphlebae. These have thick-walled cells and are stiff, like thorns or spines in recent plants. The sporangia have thick walls and are terminally to the last page branches. They should have opened by an apical pore. The spores are spherical and have a diameter of 32 to 40 micrometers. They were homospor.

Stauropteris burntislandica dates from the Mississippian. The axes are similar Stauropteris oldhamia that Aphlebae but are quite variable. The Aphlebae are irregularly branched, individual segments are up to 4 mm long. This species is heterosporous. The Megasporangien were described under the name Bensonites fusiformis. They are spindle- shaped and about 1.3 mm long. The bottom half is parenchymatous, the top is hollow with a wall of a cell layer. There are usually two megaspores. Their size is up to 580 microns. The microsporangia are egg-shaped and about 0.6 mm long, their wall is one cell layer thick. The microspores are about 30 microns in size and trilet. Whether micro and Megasporangien stood on a plant or on different plants is not known.

Stauropteris biseriata comes from the lower to middle Pennsylvanian of North America. The side axes are in two rows ( distich ), and are in the axils of Aphlebae, which are supplied by the vascular bundles. Reproductive structures are not known here.

Other genera

Multifurcatus tenellus similar to Stauropteridales. It dates from the Carboniferous of China. Its major axis has a diameter of up to 3 mm to form three nodes per page axes. At the nodes of the side branches are dichotomously branched side axis, the terminal wearing a sporangium. You could be heterosporous.

Gillespiea is considered Devonian representatives of Stauropteridales. Gillespiea randolphensis has smooth, quadriseriat branched axes. Larger axes have a protostele and are three to four square in cross-section, small axes are round. The Megasporangien are spindle-shaped with a blunt end. They are available individually or in pairs to small axes which are where other Stauropteridales are the Aphlebiae. Megasporangien are 1 mm long and contain one to two trilete spores of approximately 160 micron in size. The microsporangia are not known.

Rowleya trifurcata comes from the Westfalium A from Lancashire and has a protostele triseriate and lateral axes. The protostele is tetrarch, and resembles that of Stauropteris. Small side axles are round, are in pairs and are interpreted as leaves.

Documents

• Thomas N. Taylor, Edith L. Taylor, Michael Krings: Paleobotany. The Biology and Evolution of Fossil Plants. Second Edition, Academic Press 2009, ISBN 978-0-12-373972-8, pp. 405-407.

• Extinct plant
• Ferns
• Moniliformopses