The Flowering of Gondwana

by Mary E. White, Jim Frazier (Contributor)

Illustrated with nearly four hundred magnificent photographs of fossils and living plants, this book tells the story of Australia's remarkable floral heritage, from its genesis through to its last stages of evolution, while also providing a general introduction to major patterns in the history of plant life. Over 50 million years ago when Australia broke away from the great supercontinent known as Gondwana, which comprised all the major southern landmasses, a modern aspect flora was already established and rainforests covered most of the land. The remnant rainforests of Australia are ancestors of a unique flora that evolved in isolation as the continent moved slowly northward to the position it occupies today. Here Mary White traces the evolution of plants from the earliest times when all life was confined to the water and the land was barren, and describes the emergence of the first land plants about 400 million years ago. Her portrayal of Australia's flora includes the changes that have since come with the arrival of settlers and their crops of exotic plants.


The fossil record studied in this book is a tantalizing key to visualizing the world as it once was. The plants tell us of past climates, conjure up a picture of ancient landscapes, and explain configurations of land and sea on the ever-changing surface of the earth. A single source of information on fossil floras and environments of past ages, The Flowering of Gondwana enables scientists and general readers to follow Australia's plant ancestry and to appreciate the individuality that has evolved from an inheritance in common with plants from other southern lands.

256 pages, Hardcover

First published May 16, 1990

Reviews

[Bill Leach]

This book reviews the development of plant life, concentrating on Australia which was part of Gondwana. Australia has rock formations from all major geological periods of the Phanerozoic Eon during which life evolved. Macrofossils and microfossils - spores and pollen - from these periods portray the development of plant life. While plant life developed in Gondwana, the separation of Australia from the other continents resulted in 30 million years of independent evolution. Eighty percent of plant species and thirty percent of the genera of Australia are endemic. Of note are the scleromorphic adaptions to dry climates that result in leathery, spiny and diminished leaves. These plants are also adapted to withstanding fires and many, such as Banksias, depend on the fires for germination.

Algae exhibit a number of reproductive systems whereby they produce haploid stages which subsequently combine to form diploid plants. During the Silurian Period (420-385 mya) land flora evolved from algae, developing tissues to support the plants, vessels to conduct water and nutrients, skins to protect the plant, photosynthetic organs and stomata for gas exchange. The symbiotic relationship with bacteria developed very early as shown by the Scottish Rhynie Flora (about 400 mya) where fungal threads are seen inside fossilized plant cells.

The subsequent evolutionary sequence is described by geological period.

Late Silurian to Early Devonian (420-385 mya) - the earliest and simplest plants were of the Cooksonia Flora, where sporangia are supported by fine stems. Similar plants are still in existence such as Psilotum. Plants evolved quickly, resulting in the diverse Baragwanathia Flora in the Late Silurian where many of the plants were Lycopods.

Mid Devonian to early Carboniferous (385-325 mya) - plants developed a cambium, the strength of which allowed them to grow into trees. Giant clubmosses, horsetails and ferns dominated the landscape.

Mid Carboniferous to early Permian (325-285 mya) - the onset of an ice age caused the giant clubmoss flora to die out. The dominant flora became the Rhacopterids: seed-ferns with a primitive leaf structure.

The Permian (275-245 mya) - rapid evolution resulted in the Glossopterids which dominated the flora of this period. The reproductive structures were diverse in form and appear to have lead to the development of major plant families including the conifers, cycads and possibly the angiosperms.

The Triassic (245-208 mya) - a warm and wet interval during whish seed-ferns, podocarp conifers, ferns, gingkos appeared, while the Glossopterids disappeared.

The Jurrassic (208-144 mya) - hot and wet, the conifers, cycads, ferns, seed-ferns, ginkgos, smaller lycopods and horsetails flourished.

The Cretaceous (144-66 mya) - the start of the breakup of Gondwana, cooling and sea level rise provided an opportunity for the development of the Angiosperms.

The Tertiary (66-1.6 mya) - continental drift isolated Australia, preserving its Gondwana heritage. Toward the end of this period, the center of Australia became increasingly dry giving rise to sclerophyll scrublands and grasslands. The pollen record shows the development of the Antarctic Beeches, the Proteas, She-Oaks, Eucalypts, Mistletoes, Wattles, Grass-tees and Kangaroo Paws developed over this period.

Beautifully illustrated with photos of important fossils, the book gives a terrific view of plant evolution and of the uniqueness of the Australian flora.