I'm working in the development of an identification and recognition software for trees from my country, based on picture scanning and interactive dichotomous keys.
Flavia, This program is based on the paper A Leaf Recognition Algorithm for Plant classification Using Probabilistic Neural Network, by Stephen Gang Wu, Forrest Sheng Bao, Eric You Xu, Yu-Xuan Wang, Yi-Fan Chang and Qiao-Liang Xiang, published at IEEE 7th International Symposium on Signal Processing and Information Technology, Dec. 2007.
PC/Mac-based Lucid keys to New Zealand plants are hosted on the Landcare Research server at http://www.landcareresearch.co.nz/resources/identification/plants. Over the next 2 years, we will be producing smartphone app. versions using the new Lucid Mobile - http://www.lucidcentral.com/. This is following similar initiatives in Australia and elsewhere.