SPHENOPHYLLUM (Plate 2)
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SPHENOPHYLLUM (Plate 2)
The name Sphenophyllum refers to both stems and leaves of this extinct genus, which was related to the scouring rushes—note its resemblance to Annularia.
A small herbaceous plant, Sphenophyllum formed much of the swampy undergrowth of the Pennsylvanian Period and is abundant among Illinois fossils. It had a slender, ribbed stem bearing whorls of delicate, wedge-shaped leaves, generally less than three-fourths of an inch long, attached around the stem in multiples of three.
The cones of this group also are slender, delicate structures, bearing a number of sporangia, and are correctly called Bowmanites, although they also have been called Sphenophyllostachys. These fossil cones frequently are found in Illinois.
Sphenophyllum first appeared during the Devonian Period, some 300 million years ago, but did not become abundant until Pennsylvanian time. The genus continued through the Permian but died out in Triassic time.
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