A Rare plant that is beautiful

Caladenia ornata is a small, pink-flowered ground orchid that is found in woodlands and heathlands of western Victoria (and south-eastern South Australia).  It has been recorded from only 17 sites, most of which are within national parks or other conservation reserves.  It is classified as vulnerable in Victoria.

Beauty, along with rarity, is clearly an important component of the amount of interest (and energy) people will assign to plants.  Few people would mourn the extinction of a small annual sedge or native thistle but the loss of an orchid or waratah or banksia would be almost unthinkable.   As a consequence it should not be surprising to note that some plant groups have a higher proportion of species that have been categorised as rare or threatened than others.  For example, about 60% of the orchids and 72% of the grevilleas (two very popular, attractive and well-studied groups) are considered to be rare or threatened while the average for all Victorian native species is around 45%.

The process for listing species as rare or threatened is, in most cases, a carefully considered one and the botanists who create the lists are not usually prone to raising a conservation status simply because the species is attractive or interesting.  The reason for the larger than normal proportion of rare or threatened species is a taxonomic one and the intensity of taxonomic research does tend to be affected by these attributes - this is particularly so for orchids. 

There are more books on orchids, and how to recognises them, than any other plant family; all of which are filled with colour illustrations, detailed descriptions of flowers and, importantly, the variation in flower colour, size, shape, ornamentation and perfume both between and within species.  There are orchid societies, orchid shows, orchid journals, and those who study orchids call themselves orchidologists (students of other plant groups rarely use family or generic names to define their profession).  It's a popular and specialist area, and is so mostly because of the beauty and intricacy of orchid flowers.

It is the intense study of orchids that has lead to the large, and growing, number of orchid species, many of which are redefinitions of subspecies, varieties or colour forms of other species, rather than genuine discoveries of previously unknown plants.  Caladenia ornata was until 2001 considered to be a poorly known variety of the widespread species Caladenia carnea.   Now that its identity has been raised to species level it has been subject to more intense scrutiny, the distribution is better known, and the conservation classification of vulnerable can be applied with some confidence. 

This pattern has been repeated many times over the past couple of decades with orchid species that were once considered to be widespread and common  being segregated into several species (e.g. Caladenia patersonii, Dipodium punctatum, Pterostylis longifolia), each of which is less common and more restricted in its habitat.  As a consequence the number of orchid species which have been described in taxonomic literature and recognised for Victoria has increased by 15% in the past 15 years, while the proportion of orchids that are considered to be rare or threatened has increased from 40% to 60% in that time.  Clearly taxonomic scrutiny of orchids is creating new species an increasing proportion of which are being classified as rare or threatened.

The genus Grevillea, which the Society for Growing Australian Plants (SGAP) describes as the "..most popular and widely planted of all Australian plant genera..", and one which has been received a great deal of attention from taxonomists in recent years, has been subject to a similar process of increasingly refined specific and infra-specific segregation by taxonomists.  By virtue of the small ecological valence and geographic range of the newly described entities, a greater proportion of them are classified as rare or threatened.  This proportion has increased from 45% in 1994 to the current level of 72%.