Families of Vascular Plants - Botany 307F Gymnosperms

Pinophyta ("Gymnosperms")

These four groups of extant seed plants all produce ovules unenclosed by any sporophyte tissue. Some phylogenetic analyses (Doyle 1996) suggested that the conifers and Ginkgoales, together with a number of extinct groups, form one clade, the sister group of which is a clade containing the Gnetales and flowering plants ("Angiosperms"). The position of the Cycadales in these analyses was ambiguous. More recent results suggest that the relationship between the Gnetales and flowering plants is much more remote (for details click HERE or HERE).

Living "Gymnopserm" Groups - comparison

Cycadales Ginkgoales Gnetales Pinales
(incl. Taxaceae)
Stem woody, unbranched branching trees with dimorphic shoots (long, short) woody trees, shrubs, lianes, hemicryptophytes branching woody plants, often with long and short shoots
Leaves large, typically pinnate compound leathery, fan-shaped leaves simple, but diverse in size and form needle- or scale-like, arranged in spirals, or whorled
Reproduction dioecious dioecious (XX females,
XY males)
mostly dioecious mostly monoecious
Female structures Megasporophylls leaflike, in cones (except Cycas); seeds large ovules in pairs, seed large ovules in compound flower-like, strobili; double fertilization ovules on ovuliferous scales in compound seed cones, or solitary and terminal (Taxaceae)
Male structures Microsporophylls scale-like or peltate; sperm with spiral band of flagella microsporophylls on catkin-like axes; sperm with spiral band of flagella Microsporophylls in flower-like structures on compound strobili; sperm reduced to two nuclei in pollen tube Microsporophylls on simple strobili; sperm reduced to two nuclei in pollen tube
Distribution Nine genera, Central America, S. Africa, E. Asia sole, monotypic genus Ginkgo cultivated in China; introduced elsewhere three genera, with varying distributions 57 genera distributed variously, world-wide
History group 200 M y old Ginkgo-like leaves 200 M y old fossils extremely sparse group more than 200 M y old, with "living fossils" Metasequoia (click HERE to read a recent account of the history of its discovery) and Wollemia.

Flora North America Editorial Committee (1993) - Gymnosperms (Vol. 2)


Sporne (1974)

[back to top]

| What are plant families? | How do we distinguish them? | How and why do we study them? | Selected vascular plant families of Ontario | Reading List | Course outline |

|EEB 337H Home Page | What's New | U of T Ecology & Evolutionary Biology | University of Toronto |

© 2008 Department of Ecology & Evolutionary Biology and 1996-2006 Botany Department, University of Toronto.

Please send your comments to tim.dickinson@utoronto.ca; last updated 11-Oct-2008