Karkeniaceae is an extinct family in the order Ginkgoales. It contains the single genus ''Karkenia''. It is distinguished by "Ovulate organs consisting of a peduncle and helically arranged, up to about 100 small, orthotropous but incurved

ovules In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

; pedicel present;

nucellus In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

largely free." Unlike other ginkgoales, the seeds are borne on

cone A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines con ...

-like aggregations. Ovuluate organs of ''Karkenia'' are associated with leaves of the ''

Ginkgoites ''Ginkgoites'' is a genus that refers to extinct plants belonging to Ginkgoaceae. Fossils of these plants have been found around the globe during the Triassic, Jurassic, Cretaceous, with fossils also known from the Paleogene. The name was created ...

'', ''

Sphenobaiera ''Sphenobaiera'' is a form genus for plant leaves found in rocks from Triassic to Cretaceous periods. The genus ''Sphenobaiera'' is used for plants with wedge-shaped leaves that can be distinguished from ''Ginkgo'', ''Ginkgoites'' and ''Baiera'' ...

'' and '' Eretmophyllum'' types. It is known from the Hettangian to

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

of both Hemispheres.

References

Ginkgophyta Prehistoric plant families {{Paleo-gymnosperm-stub