Similar compilations to the British ``Plant Finder'' (Whitbourne, Worcestershire, UK: Headmain Ltd., 9.99) exist in Germany, Canada, and the United States. The four-year-old US book has a long title: ``Andersen Horticultural Library's Source List of Plants and Seeds'' (Chanhassan, Minn.: Minnesota Landscape Arboretum, $29.95 postpaid). The work of Richard Isaacson, this list ``is going to be updated every three years,'' he says. He aims at a balanced spread of nurseries and seed sellers throughout the US and Canada, in all 400 retail and wholesale outlets. One criterion is that these suppliers ``have to ship.'' He lists 40,000 different plants and seeds, including vegetables and fruits. But ``not too many indoor plants,'' and, like ``The Plant Finder,'' no orchids, cacti, or succulents.