Mark spent most of his life working as an esteemed botanist and senior curator in the Natural History Museum in London but his career took a surprising turn which now sees him turning his talent to helping the police crack cases. Mark told Ryan about the work of a forensic botanist.
'Murder Most Florid: Inside the Mind of a Forensic Botanist' by Dr Mark A. Spencer is available now.
If you could write a letter that you have never sent, who would you send it to and what would you say? We want you to write it now and post it to the Ryan Tubridy Show, Donnybrook, Dublin 4. This morning Ryan read some more letters from listeners and spoke to Bernie about the letter she wrote to her daughter Caoimhe.
Armando Iannucci is the man behind 'The Thick Of It', 'Veep' and 'The Death Of Stalin'. His new film is an adaptation of the novel 'David Copperfield' and Armando spoke to Ryan about bringing his typically comedy chops to a Charles Dickens' classic.
Commander Chris Hadfield was the first Canadian to walk in space. He's a former Air Force fighter pilot and has undertaken three space shuttle missions. He joined Ryan in studio to talk about his fascinating life and career.