The progymnosperms are an extinct group of woody, spore-bearing plants that is presumed to have evolved from the
trimerophytes, and eventually gave rise to the
gymnosperms, ancestral to
acrogymnosperms and
angiosperms (flowering plants).[1] They have been treated formally at the
rank of division Progymnospermophyta or class Progymnospermopsida (as opposite). The stratigraphically oldest known examples belong to the Middle
Devonian order the
Aneurophytales, with forms such as Protopteridium, in which the vegetative organs consisted of relatively loose clusters of axes.[2]Tetraxylopteris is another example of a genus lacking leaves. In more advanced aneurophytaleans such as Aneurophyton these vegetative organs started to look rather more like fronds,[3] and eventually during Late Devonian times the aneurophytaleans are presumed to have given rise to the
pteridosperm order, the
Lyginopteridales. In Late Devonian times, another group of progymnosperms gave rise to the first really large trees known as Archaeopteris. The latest surviving group of progymnosperms is the
Noeggerathiales, which persisted until the end of the
Permian.[4]
^Stewart WN, Rothwell GW (1993). Paleobiology and the evolution of plants. Cambridge University Press. p. 521pp.
^Lang WH (1926). "II.—Contributions to the Study of the Old Red Sandstone Flora of Scotland. I. On Plant-Remains from the Fish-Beds of Cromarty. II. On a Sporangium-bearing Branch-System from the Stromness Beds". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 54 (2): 253–79.
doi:
10.1017/S0080456800027599.
S2CID131163187.
^Serlin BS, Banks HP (1979). "Morphology and anatomy of Aneurophyton, a progymnosperm from the Late Devonian of New York". Palaeontographica Americana. 8: 343–359.