ISSN:
1615-6110
Keywords:
Primitive angiosperms
;
Chloranthaceae
;
Palaeobotany
;
Cretaceous fossils
;
floral evolution
;
flower morphology
;
pollen
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Fossil chloranthoid androecia,Chloranthistemon endressii gen. et spec. nov. are described from the Upper Cretaceous (Upper Santonian or Lower Campanian) of Scania, southern Sweden. They are three-lobed and dorsiventrally flattened with all pollen sacs borne laterally and inclined toward the presumed adaxial surface. The central lobe bears two pairs of pollen sacs, the lateral lobes a single pair each. The morphology, anatomy and valvate dehiscence of the fossil androecia is very similar to that seen in extant species ofChloranthus andSarcandra, but the in situ pollen differs from that of all extantChloranthaceae in being spiraperturate. A single chloranthoid androecium from the Lower Cretaceous (Upper Albian) of Maryland, North America has a more generalized structure thanChloranthistemon endressii. It consists of three stamens that are fused at the base, and each stamen bears two pairs of oppositely positioned pollen sacs. Combined with anatomical information from recentChloranthus the Lower Cretaceous specimen suggests that the androecium in the living genus has arisen by fusion and other modifications of three separate stamens each with a normal complement of four pollen sacs. The structure of both the Upper and Lower Cretaceous androecia suggest that these fossilChloranthaceae were insectpollinated. Macrofossil evidence combined with information from dispersed pollen indicates that theChloranthaceae diversified early in angiosperm fossil history and were an important component of Mid-Cretaceous plant communities.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00936003
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