Background

When we introduce second year Botany students to the skills and techniques of plant identification, we are compelled to use the standard publication, which uses black and white photos, and a single entry dichotomous key. With this type of key students must answer the first question presented, such as 'anthers opening by slits, or anthers opening by pores', before they can move on to the next question, and so on until the plant is identified. The student may be holding a plant with a very distinctive and colourful flower, but cannot use this visual information to hasten identification. This can be a mind numbing and complicated process.

In the third year subject Biodiversity and Evolution of Plants I wanted to teach a practical class on tropical rainforest biodiversity, and this required the students to identify rainforest plants. The first problem was that the Leaf Atlas available for tropical rainforest plants was expensive, and was only going to get more expensive as other categories of plants and more species were added. Secondly, from my experience with second year Botany students, I knew that the traditional taxonomic methods for plant identification were not likely to motivate them to accurate identifications. The solution to this was the development of a digital version of the Leaf Atlas.

Description

I previously developed a Leaf Atlas in collaboration with Bernie Hyland from the CSIRO Division of Plant Industry, who is also Adjunct Associate Professor in the Department of Botany at the University of Adelaide. This Atlas is a comprehensive collection of over 1000 X-ray images of the leaves of Australian tropical rainforest plants. The images illustrate structures in the leaves that are characteristic for each species and thereby allow accurate identification of samples, a considerable improvement on traditional black and white line drawings.

In our third year Biodiversity and Evolution of Plants practical classes we ask students to use a botanical key (computerised data base of botanical characteristics developed by Trevor Whiffin from Latrobe University and Bernie Hyland) to identify botanical specimens. Final identifications are achieved by visually comparing the samples with X-ray images of the leaves in a Leaf Atlas. While the Botanical Key is readily available on computers in the Department of Botany's teaching laboratories, the expense of the Leaf Atlas limits its availability to students, causing frustration and restricting learning opportunities. Compared to the Botanical Key, the Leaf Atlas is a cumbersome tool to use and students require demonstrator support.

With the approaching revision of the Key and Atlas, we had the opportunity to compile the images in digital form into an image data base and thereby make them more readily available. Powerful information retrieval tools were then integrated with the database. Ultimately, the digital Leaf Atlas could be integrated with the existing Botanical Key to provide a seamless botanical reference tool. The development of integrated botanical databases has been one major focus for the Rainforest Cooperative Research Centre

Aims

The project aims to:

• Allow students to work more effectively in practical classes
• Help students to develop skills in information retrieval
• Allow students to experience the roles and value of Information Technology to the contemporary discipline of Botany

Process

To be usable, the many images in the Leaf Atlas had to be scanned at high resolution. Each uncompressed image occupies approximately 1 megabyte of disk space and so must be heavily compressed for obvious practical reasons. It is vital that no visible artefacts are generated by the compression process and a fractal compression facility produced by Iterated Systems Inc. was selected by the team as the best available option. A compression ratio over 10:1 is being achieved (compressed image size < 100 Kbytes) by Trevor Whiffin at Latrobe University, with no apparent reduction in image quality.

A cataloguing system has been developed for the management of the digital images. This has allowed efficient retrieval of the images and includes an index linking the images to the Botanical Key. The digital Leaf Atlas was first used in beta version with students in 1998.

The first subject to benefit from the digital Leaf Atlas was Biodiversity and Evolution of Plants. Students in this course spend 10 hours in the laboratory working with Australian Tropical Rainforest Trees and they were able to work far more efficiently and independently with the digital Leaf Atlas. Using a digital format tripled the number of actual plants that students could identify. The use of digital technology, including extensive on-line help, has made possible a staff to student ratio of 1:21, as compared with 1:6 in other similar practical classes. It may even be possible to extend this ratio further, as we only had 21 computers to work with. Importantly, the students enjoyed using the digital Leaf Atlas in comparison with book based keys and atlases.

We anticipate that the digital Leaf Atlas could become a valuable resource in other undergraduate subjects including Botany II. In addition to applications in undergraduate teaching, we also expect the Leaf Atlas to be a useful research tool for postgraduate students and staff. Already one student has used the Atlas on a laptop to identify seedlings associated with an endangered species she was studying for her Honours project. The Leaf Atlas and Botanical Key are also available to students on field trips at their accommodation in North Queensland.

The digital leaf atlas and botanical key are available to students on personal computers in the botanical teaching laboratories. The leaf atlas is stored on a CD-ROM, although network-based distribution is also possible. The Leaf Atlas will be available for purchase after November in 1998.

Evaluation

A standard Student Evaluation of Teaching was administered and found that the students were happy with the practical component of the course, although the questionnaire did not specifically address the new digital technology.

Prior to the development of the Leaf Atlas the following criteria for success were developed:

• the success of the production of the digital Leaf Atlas
• the educational benefits to students and more efficient use of laboratory time and demonstrator resources

The Leaf Atlas achieved both of these goals.

Our plans to publish the digital Leaf Atlas as a component of the next edition of Australian Tropical Rainforest Trees and Shrubs will involve the publishers in an evaluation of the previous points and also market issues.

We anticipate that the digital leaf atlas will help to make the next edition of Australian Tropical Rainforest Trees and Shrubs a common botanical tool.

The image database will eventually be valuable for other applications beyond sample identification. The digital medium allows fine image detail to be stored and magnified making the database a valuable resource for other teaching including the structure and function of anatomical features. There is also no reason, technically, why the same approach could not also be taken with the flora of South Australia.

Contact

Other links

Other WWW sites with information related to this project are:
• CSIRO Home page
• CSIRO Tropical Forest Research Centre

last updated 29.05.99