Orchids - Budawang Coast Nature Map

Overview

Some Notes on Native Orchids

Most orchids grow in the ground (terrestrial) and are deciduous; but others grow in trees (epiphytes) and others on rocks (lithophytes), or sometimes on either.

Most terrestrial species are identified by either a single leaf or group of leaves (rosette), while only a few have no leaves. The majority of leafless terrestrials are saprophytic, indicating their reliance on a mycorrhiza fungus in the soil for their survival. Another small group of terrestrials have leaves visible at all times (evergreen).

Orchids have six floral parts, collectively referred to as the perianth segments. These are individually called petals, sepals and the labellum, which is a greatly modified petal. In many terrestrial orchids the segments are often difficult to view separately; for instance, the Pterostylis genus has a hood or galea, a combination of the dorsal sepal and petals, whereas within the Corybas group, flowers are dominated by the dorsal sepal and labellum.

Successful identification of native orchids in the Atlas of Life Budawang Coast using photographs needs to show these components clearly, in particular the labellum, the shape and texture of which very often determines the difference between one species and another. The colour of a native orchid is not always a reliable distinguishing feature.

The male and female sexual parts of the flower - the stamens and style - are combined to form the column. Located centrally in the flower, these parts are conspicuous and close together. Pollen in most orchids is known as pollinia, which is an amalgamation of very small grains into a single unit, removed by an insect during the pollination process. Pollination is achieved in most native orchids by an insect, often matched to a specific orchid species, and is a process that is occasionally observable. Pheromones, a kind of scent, are emitted by the plant to attract the insect, in some cases using floral mimicry to deceive it into responding to the markings of a female of the species. Other plants, such as Caleana major (Large Duck Orchid) use a trigger mechanism to trap the pollinator inside the plant until the pollinia is removed.

Identification and naming: check through the orchid 160 species list known to exist in ALBC and see if a match can be made. Orchid Species of the Shoalhaven (2011) by Alan W. Stephenson ISBN 978-0- 9581679-1-8 is available in some local libraries and bookstores for reference. The Australian National Botanic Gardens has a CD available to help with key identification: https://www.anbg.gov.au/orchids/index.html.