The water lily cross : an English garden mystery / Anthony Eglin.

Enhanced descriptions from Syndetics:

Lawrence Kingston is asked to search for a botanist friend who has gone missing. With nothing but a scrap of paper with a bewildering cryptic message, he begins to investigate. He discovers that his friend was experimenting with aquatic plants and has stumbled on a horticultural breakthrough with staggering implications, one that could ultimately generate billions of dollars in revenue: a unique and giant form of Amazonian water lily. Convinced that influential people are involved in the disappearance, he pursues more leads, but circumstances beyond his control plunge him deeper into jeopardy and a corporate world of ruthless, greedy men who are not to be stopped. Kingston presses on, knowing that his missing friend's life--and his own--both hang by a very slender thread. As with the highly acclaimed The Lost Gardens , Eglin brings his botanical and literary skill to this new mystery.