orchid

Dendrobium species are attractive, conspicuous and numerous along the entire eastern coast of Australia, and are popular plants for culture and breeding of colourful hybrids. In contrast to the other books in the series so far, where a selection of species was made, all Australian species and their variants (around 80) are included. There is a full spectrum of plant form from some of the smallest mat-forming dendrobiums to the largest in the genus, being over two metres tall and several metres across. The unusual and rarer species of Cape York Peninsula and central Queensland are uncommon in collections and seldom seen, requiring travel to remote places. Some of the most striking Dendrobium habitats are illustrated.

There have been a number of approaches to the classification of Dendrobium and related genera over the past 30 years. Classification and nomenclature are always evolving as new information becomes available. Genera Orchidacearum Volume 6 (2014) included evidence from morphology, DNA and all other areas of study and provided an international consensus for Dendrobium, bringing a long-awaited degree of stability to the genus. This book follows the Genera Orchidacearum Vol. 6 approach and the Kew Monocot Checklist, and considers all available published evidence on the genus. An identification key to the sections is provided, and species are arranged in a checklist according to sections.

The terrestrial orchids of Victoria are reputed to attract pollinators by deception and the highly specialised strategies used were well covered in Orchid Pollinators of Victoria, 4th edition. The nectar-rewarding orchid pollinators received only basic treatment and are elaborated on in this companion volume. Initial observations indicated different aspects to orchid-insect relationships and this deserved more attention. Orchids that have food-rewards attract a greater variety of visitors, but these include non-pollinating or pollinia-robbing insects. To compensate for losses a large number of flowers are needed on the same plant, but these are often cross-pollinated and geitonogamy is common. The various strategies have evolved from adapting to environmental changes to sustain populations, each of which producing ample viable seeds for eventually some to become adult plants. Nectariferous orchids may be the least specialised of the Victorian taxa, readily adapting to changes that occur at a natural rate, but they are far from being safe. Habitats in the few areas left since colonisation are changing too quickly, and deteriorating at an alarming rate. Destruction of ecosystems continues, critically reducing the suitable orchid habitats by clearing and logging. This is accelerated by prescribed burning and many of the endangered species are driven to extinction.