Francis Hallé (1938–2025), founder of the study of tree architecture

Francis Hallé (1938-2025) was one of the most influential French botanists of the last century. He founded plant architectural analysis, showing that post-embryogenic development follows intrinsic, species-specific rules, and that the immense diversity of tree forms can be captured by a finite set of recurring architectural models. He also co-invented the Radeau des Cimes, a canopy-access platform that transformed tropical forest research by making the canopy directly observable and sampleable, and by catalysing ambitious, multinational expeditions. Beyond research, Hallé was an extraordinary communicator: through books, drawings, and public talks, he fought plant blindness and taught generations to look at plants differently. In his final years, he led a major project with the aim to recreate a large, primary forest in Western Europe. Hallé died on 31 December 2025, leaving a scientific, cultural, and ecological legacy that will long outlive him.