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Chloranthaceous floral structures from the Late Cretaceous of Sweden

Helena Eklund, Else Marie Friis and Kaj Raunsgaard Pedersen
Plant Systematics and Evolution
Vol. 207, No. 1/2 (March 1997), pp. 13-42
Published by: Springer
Stable URL: http://www.jstor.org/stable/23643105
Page Count: 30
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Chloranthaceous floral structures from the Late Cretaceous of Sweden
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Abstract

New chloranthaceous floral structures from the Late Cretaceous (Late Santonian/Early Campanian) of Scania, southern Sweden, have provided important new information on the Chloranthistemon plants. The material includes well preserved fragments of inflorescence axes with flowers in situ documenting that Chloranthistemon flowers were bisexual and closely resembled those of extant Chloranthus (Chloranthaceae). An emended diagnosis is given for the type species of the genus, Chloranthistemon endressii, and a new species, C. alatus, is described. The flowers of Chloranthistemon are small, perianthless and strongly zygomorphic, consisting of a tripartite and broadened androecium borne in an abaxial to lateral position on the monocarpellate ovary, and arranged in the axils of decussate bracts. Stamens are either completely free (C. alatus), or free at the base and coherent at the apex (C. endressii). The apical connective is extensive in both species; elaborated into conspicuous wing-like structures in C. alatus, or into a massive and shield-like structure in C. endressii. Pollen grains of C. endressii are spheroidal, and reticulate and spiraperturate, while those of C. alatus are ellipsoidal, tectate and foveolate with a unique combination of a distal colpus and a proximal furrow (colpus?) perpendicular to each other. Ovaries observed in well preserved flowers of both species are small and undifferentiated. Larger, dispersed fruits of chloranthaceous affinity are abundant and distinct, and probably represent at least two or three species, but cannot be linked with certainty to any of the Chloranthistemon species described here.

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