What is an identification tool or key?

What is an identification tool or key?

If you want to identify a tree, a weed, a bird or an insect, how would you go about it? To identify a bird, you might use a published bird book or a bird app – and flick through the images. You might do the same for certain tree species. However, if you are in Australia and you want to identify a Eucalyptus tree, there are over 1,000 Eucalyptus species, and even more Wattle species. To scan through a tree guide of images to make an identification would be very tedious. In such cases, a more systematic approach is needed and, over time, two taxonomic identification systems (or keys) have been developed to meet this need.

Dichotomous keys

Since the time of Linnaeus (1707 – 1778), naturalists and taxonomists have developed and published dichotomous, or pathway, identification tools or keys. These keys consist of a series of linked statements (generally couplets) that describe certain features. For instance, imagine you want to identify an insect using a dichotomous key. One simple couplet in the key might be:

10(a) ‘Wings present, has four wings, wings are broad’ – go to couplet 12
10(b) ‘Wings present, has four wings and wings are narrow’ – go to couplet 13.

By selecting descriptions that match the specimen, you follow a tree-like (dichotomous) pathway to a final identification.

While dichotomous keys are still published in books and journals, digital technology enable them to be published online, allowing users to follow a pathway of characters (often illustrated) by moving from one web page to the next. However, a significant problem with dichotomous keys is the ‘unanswerable couplet problem’. What if a user cannot decide which couplet statement is correct for the specimen in question? For instance, one node might be ‘flowers red’ or ‘flowers white’, but if the plant is not flowering at the time, progress through that key ceases.

Matrix keys

Digital technology has also enabled an alternative, matrix key system to be developed. Matrix keys allow users to answer questions about features of the plant or animal in any order, at the same time, indicating which taxa match the selected answers and which don’t. Since the late sixties, several software platforms for constructing matrix keys have been developed. The Lucid system, first developed at the University of Queensland some two decades ago, is now managed and further developed by Identic Pty Ltd – a Brisbane based company.

Examples of Lucid keys

While Lucid keys can be deployed as CD/DVD and USB products, most Lucid keys now are deployed via the web or as Lucid Mobile apps. You can search for and access lucid web keys by going to the Lucid key Search function. The Lucid Mobile apps section provides examples of Lucid apps.

Lucid Mobile apps

To make Lucid identification tools more accessible, the Lucid team have developed a generic Lucid Mobile platform. Any Lucid key developed using a recent version of the Builder can be published as a Lucid Mobile app. Many of these apps are free to download from Google Store (Android) or iTunes (Apple).

You can see a range of Lucid Mobile apps and web based keys by going to the following sites: