''Williamsoniaceae'' is a family within the
Bennettitales
Bennettitales (also known as cycadeoids) is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous. Bennettitales are among the most common Mesozoic seed plants ...
, an
extinct group of
seed plants
A spermatophyte (; ), also known as phanerogam (taxon Phanerogamae) or phaenogam (taxon Phaenogamae), is any plant that produces seeds, hence the alternative name seed plant. Spermatophytes are a subset of the embryophytes or land plants. They inc ...
within the
Cycad
Cycads are seed plants that typically have a stout and woody ( ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or ...
ophyta subdivision. Members of this family are believed to have been around two meters tall and with widely serrate leaves along a central stem. Reproductive organs of the Williamsoniaceae have varied widely in the fossil record but almost all have been found to be borne on stalks emerging from a ring of leaves.
Reproduction
This family is different from
Cycadeoidaceae by having the presence of
cones
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 ...
leaving the major axis and lateral branches associated with a long
peduncle covered by
bracts. Some of this family reproduce by
sporangia
A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cy ...
and others only produce
ovule or
pollen sacs.
[Paleontologia Paleovertebrados e Paleobotânica'']
Autor : ''Ismar de Souza Carvalho.'' Editora Interciência.
References
Bennettitales
Triassic plants
Jurassic plants
Cretaceous plants
Prehistoric plant families
Triassic first appearances
Cretaceous extinctions
{{cretaceous-plant-stub