There are now two free Android phone apps, one for flower
identification, http://goo.gl/lkOZf, and one for tree identification,
http://goo.gl/t5WyY (also one for birds, http://bit.ly/floweridapp).
They're tiny apps, based on my (fairly popular) ID programs on the
web, e.g.: http://www.realtimerendering.com/flowers/flowers.html.
Fatherly pride compels me to note that these were created by my older
son, a computer science major. Enjoy!