Flora of the Otway Plain and Ranges 1

Orchids, Irises, Lilies, Grass-trees, Mat-rushes and Other Petaloid Monocotyledons

Enid Mayfield

• Publisher: CSIRO PUBLISHING
• Year: 2010
• Print ISBN: 9780643098046
• eBook ISBN: 9780643102002
• Topic: Biological Sciences
• Subtopic: Biology
• Index: Biological Sciences

The Otway region of Victoria, with its temperate rainforests, mountain ash forests, heathlands, plains and coastal dunes, has an extraordinarily rich and diverse flora. The first volume of Flora of the Otway Plain and Ranges covers the orchids, irises, lilies, grass-trees, mat-rushes and other petaloid monocotyledonous plants.

Enid Mayfield's exquisite colour illustrations of more than 200 species reveal tiny botanical details which enable the untrained botanist to identify each species with ease. The section on orchids describes and illustrates more than 130 species, highlighting their fascinating adaptations for attracting specific pollinating insects.

The clear text and illustrations frequently draw attention to the relationship of plants to the broader environment, the impact of fire, the role of pollinators and the importance of fungi.

ORCHIDACEAE
CHARACTERISTICS OF ORCHIDS

Characteristics of Orchids

Orchidaceae is the largest flowering plant family in the world. The Otway region is exceptionally rich in orchids with over 130 species. All are terrestrials, except for the epiphyte Sarcochilus australis, and most die back each season and survive underground as tubers. Their curious flowers, rarity and intricate pollination devices are indeed fascinating.

Flowers have three sepals and three petals with the column in the middle. One petal is modified into a lip (labellum) that is often very different from the other petals and evolved to attract pollinators. It is opposite the one fertile stamen and the stigma.

Most buds twist through 180 degrees (resupination) during their development so that the labellum is on the lower side of the flower when it opens. Exceptions are Prasophyllum and Corunastylis. These keep their labellum uppermost.

Part of the stigma (rostellum) is attached to the pollinia in the anther. The surface of the rostellum (viscidium) is sticky and attaches to the pollinator. This allows the pollinia to be pulled out of the anther and transferred to another flower.

The stamens and pistil are not separate as they are in most flowers but are united into a single structure, the column. There is only one fertile anther. Typically the anther is at the top of the column. The stigma is below the anther.

In most plants pollen is powder-like but in orchids it is bound together in bundles (pollinia) that sit in the anther. These are easily carried by pollinating insects and are an efficient way to transfer pollen to the stigma of another flower.

Orchids in this region are cross-pollinated by insects like wasps, gnats and bees. It is common to find orchids that attract a specific insect pollinator.

Fruit is a capsule. Seeds are tiny and plentiful and often referred to as dust seed.

How Orchids Survive

Pollination

Pollination is the transfer of pollen from the male anther to the female stigma. The compact parcel of pollen (pollinia) either falls onto the stigma from the anther (self-pollination) or is transferred to the stigma of another flower by insects (cross-pollination).

Cross-pollination

All cross-pollination of orchids is by animals, especially insects. Many striking f...

Table of contents

• Cover
• Title
• Copyright
• Contents
• Acknowledgements
• Foreword by John Landy, AC, CVO, MBE Governor of Victoria 2001-2006
• Quick Plant Finder
• Key: What flower is this?
• Petaloid Monocotyledons
• Alismataceae Water Plantains
• Asphodelaceae Bulbines
• Asteliaceae Astelias
• Colchicaceae Milkmaids, Wurmbeas
• Hemerocallidaceae Daylilies
• Hypoxidaceae Star-flowers
• Iridaceae Irises
• Laxmanniaceae Lilies, Mat-rushes
• Luzuriagaceae Drymophilas
• Orchidaceae Orchids
• Xanthorrhoeaceae Grass-trees
• Xyridaceae Yellow-eyed grasses
• Illustrated Glossary
• Bibliography
• Index