The xylarium is the University's wood collection and contains c. 24,000 wood blocks and 13,000 microscope slides; approximately 30% of wood blocks have associated microscope slides. Approximately 5% of accessions are from gymnosperms, and the remainder from non-gymnosperms (including palms and tree ferns).
Approximately 10,000 species are represented in FHOw; 51 accessions are identified as associated with type material. Based on geographical regions, 22% of the collection is from Malaysia, 20% from tropical Africa and 12% from South America. 765 collectors have contributed to FHOw. 25% of the accessions have no collector associated with them.
The most prolific individual collectors are Krukoff, Gamble, Vigne, Breteler, Molfino, Cuatrecasas, Cooper, Stern & Brizicky and Anderson, whilst Forest Departments from former British Colonies have contributed 25% of the accessions. 60% of accessions were made between 1930 and 1960.