Williamsoniaceae

Williamsoniaceae
	Seed cones of a Williamsonia
Systematics
without rank:	Streptophyta
Empire :	Plants (Plantae)
Department :	Vascular plants (tracheophyta)
Subdivision :	Seed plants (Spermatophytina)
Order :	Bennettitales
Family :	Williamsoniaceae
Scientific name
	Williamsoniaceae

The Williamsoniaceae are an extinct group of seed plants and belong to the Bennettitales .

features

The representatives have rather slender, strongly branched stems.

The cone-like reproductive organs are located at the branch ends. They consist of either female or male organs, so they are monosporangiate. Other genera than Williamsonia also have bisporangiate cones. The sporophylls and the scales between them are not parallel, but form angles of around 300 °. The ovules and seeds are approximately circular in cross section. The cells of the Sarcotesta are horizontally oriented, short and form cone-like structures.

Systematics

The family includes the following genera:

Williamsonia
Bucklandia
Ischnophyton
Williamsoniella
Vardekloeftia
Fredlindia
Bennetticarpus
World richia

supporting documents

Thomas N. Taylor, Edith L. Taylor, Michael Krings: Paleobotany. The Biology and Evolution of Fossil Plants . Second Edition, Academic Press 2009, ISBN 978-0-12-373972-8 , pp. 732-739.
KR Spurs: The Morphology of Gymnosperms . Hutchinson University Library, London 1965. (without ISBN), pp. 87-92.

Individual evidence

↑ Gar W. Rothwell, Ruth A. Stockey: Anamtomically preserved Cycadeoidea (Cycadeoidaceae), with a reevaluation of systematic characters for the seed cones of Bennettitales . American Journal of Botany, 2002, Vol. 89, pp. 1447-1458.

Web links

Commons : Williamsoniaceae - Collection of images, videos and audio files

[1] Gar W. Rothwell, Ruth A. Stockey: Anamtomically preserved Cycadeoidea (Cycadeoidaceae), with a reevaluation of systematic characters for the seed cones of Bennettitales . American Journal of Botany, 2002, Vol. 89, pp. 1447-1458.