Orchid Identification

So you have found a flower. Is it an orchid? If so, what type?

While orchids have a very large variety of shapes, sizes and colours, they all have the same basic flower structure. It is this structure that distinguishes orchids from all other types of flowers. All orchid flowers have three petals and three sepals, positioned above a three chambered, ribbed ovary. The stigma and the anthers are combined into a single structure known as the column, which in most orchids is positioned above the labellum.

In most orchids, one of the petals is modified to become the lip, or the labellum. In most orchids in South-west Australia, the petals and sepals are similar in appearance, meaning that many orchids types appear to have 5 petals surrounding the labellum. What is the difference between a sepal and a petal? The sepals are the parts of a flower that are on the outside when the flower is in bud. They are the protectors of the flower when it is in bud. The sepal at the back of the flower is known as the dorsal sepal. Sun orchids are a type of orchid that does not have a modified labellum. The labellum in these orchids looks the same as the other petals. This is why sun orchids appear to have six petals instead of the usual five.

Some orchids, however, do not appear to have the usual petal and sepal arrangement. Greenhoods are an example of this. In Greenhoods, the dorsal sepal and two of the petals are combined to form the hood, the feature that greenhoods are named for. Other examples of orchids that do not appear to have the usual arrangement of petals and sepals are helmet orchids, hammer orchids and duck orchids.

A few types of orchids have flowers that are 'upside down' with the labellum positioned above the column and the dorsal sepal positioned at the base of the flower. Leek Orchids and Duck Orchids have flowers like this.

The pictures below show different types of orchids with the various flower parts labelled.