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Stephanospermum konopeonus (Langford) Comb. Nov.: A Medullosan Ovule from the Middle Pennsylvanian Mazon Creek Flora of Northeastern Illinois, U.S.A.

Andrew N. Drinnan, Jenai M. Schramke and Peter R. Crane
Botanical Gazette
Vol. 151, No. 3 (Sep., 1990), pp. 385-401
Stable URL: http://www.jstor.org/stable/2995410
Page Count: 17
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Stephanospermum konopeonus (Langford) Comb. Nov.: A Medullosan Ovule from the Middle Pennsylvanian Mazon Creek Flora of Northeastern Illinois, U.S.A.
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Abstract

More than 150 permineralized ovules of Carpolithus konopeonus Langford, preserved in sideritic concretions, have been recovered from the Middle Pennsylvanian (Westphalian D) Mazon Creek flora of northeastern Illinois. Ovules were borne apically on slender branching structures. The sarcotesta is bilaterally symmetrical with a pair of distinct lateral wings and, at the apex of the ovule, forms a prominent funnel that leads to the micropyle. The sclerotesta is radially symmetrical with a prominent beak and collar at the apex. The nucellus is free from the integument except at the base and extends into the basal part of the micropylar tube. The apex of the nucellus forms a distinct pollen chamber. Ovule vasculature consists of six or more bundles in the sarcotesta and a continuous sheath of vascular tissue in the nucellus. Pollen preserved in the micropyle and pollen chamber is of the Monoletes-type The Mazon Creek material is assigned to a new species of Stephanospermum Brongniart as S. konopeonus (Langford) comb. nov. and provides further evidence that this genus of ovules was produced by representatives of the Medullosales.

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